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Abstracts from publications in peer-reviewed journals

Surgical protocol and short-term clinical outcome of immediate placement in molar extraction sockets using a wide body Implant

Vandeweghe S, Hattingh A, Wennerberg A, De Bruyn H. J Oral Maxillofac Res 2011 (Jul-Sep); Vol. 2; No 3.

PURPOSE: Implant placement in molar extraction sockets can be difficult due to complex multi-root anatomy and the lack of predictable primary stability. The aim of this study was to evaluate the outcome of an 8 - 9 mm diameter tapered implant, designed to be placed in molar extraction sockets.

MATERIALS AND METHODS: Patients treated at least 1 year before with a Max implant (Southern Implants, Irene, South Africa) were invited for a clinical examination. Variables collected were surgical and prosthetic protocol, implant dimension and smoking habits. Peri-implant bone level was determined on peri-apical radiographs and compared to baseline, being implant insertion.

RESULTS: 98 implants had been placed in 89 patients. One implant had failed. Thirty-eight patients representing 47 implants (maxilla 26, mandible 21) were available for clinical examination. Mean bone loss was 0.38 mm (SD 0.48; range - 0.50 – 1.95) after a mean follow-up of 20 months (range 12 - 35). Implant success was 97.9%. Around 30 implants, a bone substitute was used to fill the residual space, but this did not affect the bone loss outcome. Bone loss was only significantly different between maxilla and mandible (0.48 mm vs. 0.27 mm) and between the 8 and 9 mm diameter implants (0.23 mm vs. 0.55 mm). A full papilla was present at 71% of the interproximal sites and irrespective of bone loss.

CONCLUSIONS: The Max implant demonstrated good primary stability, when placed in molar extraction sockets, with limited bone loss over time.

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A wide-body implant as an alternative for sinus lift of bone grafting

Vandeweghe S, De Ferrerre R, Tschakaloff A, De Bruyn H. Journal of Oral & Maxillofacial Surgery 2011

PURPOSE: The aim was to evaluate the outcome of a short wide-body implant in the atrophic posterior jaw without a grafting procedure.

MATERIALS AND METHODS: Patients treated with a tapered wide-body implant measuring 8 to 9 mm in width and 7 to 9 mm in length (Max implant; Southern Implants, Irene, South Africa) were recalled to scrutinize implant survival. Preoperative cone beam computed tomography images were analyzed to measure bone height in reference to the mandibular canal and sinus floor.

RESULTS: There were 57 implants inserted in 18 men and 24 women after a 2-stage procedure and delayed loading. The mean follow-up was 15 months (SD, 10; range, 1-32 months), with 63.2% of the implants having at least 1 year of follow-up and 26.3% having at least 2 years’ follow-up. Forty-six implants were inserted in the posterior maxilla and eleven in the mandible. Fifteen were placed in an extraction socket and forty-two in healed bone. Thirteen implants were supporting a single crown. Two implants failed, resulting in a survival rate of 96.5%, with rates of 90.9% and 97.8% for mandible and maxilla, respectively. This was not affected by gender, jaw, immediate or delayed placement, implant diameter and length, or the use of a bone substitute. The mean preoperative bone height was 7.21 mm in maxilla and 8.76 mm in mandible. In 41 cases implant length surpassed available bone height.

CONCLUSIONS: Despite the compromised bone condition and height, the survival rate of 96.5% is comparable to normal implants and, therefore, placing a wide-body implant may be an alternative to avoid grafting procedures. This is probably related to the enlarged implant surface area and the good primary stability.

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Occlusal reconstruction of a collapsed bite by orthodontic treatment, pre-prosthetic surgery and implant supported prostheses. A case report

PF Daly, A Pitsillis, C Nicolopoulos South African Dentistry Journal; 56: 278-282

A loss of mandibular molars can result in a ‘collapsed bite’ owing to tilting of teeth adjacent to the gap and overeruption of maxillary molar segments. The lost interarch and interdental space must be regained before prosthetic reconstruction. This case report documents the treatment of a patient by orthodontic, surgical and prosthetic means. The teeth were orthodontically aligned to meet predetermined surgical and prosthetic requirements. The surgical phase comprised a posterior segmental maxillae osteotomy and one-stage placement of three large- diameter implants in the mandible. Finally, the occlusion was restored with mandibular implant-supported prostheses.

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A 1-Year Prospective Study on Co-Axis® Implants Immediately Loaded with a Full Ceramic Crown

Stefan Vandeweghe, DDS;* Jan Cosyn, DDS, MSc, PhD;† Eric Thevissen, Linda Van den Berghe, Hugo De Bruyn Clinical Implant Dentistry and Related Research, 2011

INTRODUCTION: The Co-Axis® implant (Southern Implants®, Irene, South Africa) has a 12-degree angle in the implant neck to overcome angulation problems.

AIM: To examine bone loss, peri-implant health, and aesthetical outcome after 1-year follow-up.

MATERIALS AND METHODS: Fifteen single implants were placed in 14 patients in the premaxilla and immediately loaded with a screw- retained full ceramic crown. Periapical radiographs and standardized photographs were taken to determine bone loss and soft tissue changes. Plaque and bleeding levels were assessed. Patients’ satisfaction was measured using the Oral Health Impact Profile-14 questionnaire.

RESULTS: After 1 year, all implants survived and mean bone loss was 1.20 mm, with no significant changes after 6 months. Plaque levels were low and no significant changes were observed. Bleeding levels decreased during the initial 3 months, but were constant thereafter. Before final torqueing was performed after 6 months, four cases of screw loosening occurred. Also, one crown had a piece of porcelain chipped off. Patients reported an overall increase in well-being. A mean midfacial recession of 0.37 mm was observed. The mesial papilla showed a slight increase of 0.14 mm, while the distal papilla decreased 0.35 mm.

CONCLUSION: With 100% survival and stable bone levels after 6 months, the Co-Axis implant showed a good clinical outcome when immediately loaded. The use of a full ceramic crown as a first and final restoration resulted in a good aesthetic outcome with few changes in papilla fill, although midfacial soft tissue was stable only after 1 year.

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Immediately restored single implants in the aesthetic zone of the maxilla using a novel design: 1-year report

Simon D. K. Brown, Alan G. T. Payne Clinical Oral Implant Research, 2011

OBJECTIVES: To evaluate immediate placement and immediate restoration of a novel implant with a 121-angled prosthodontic platform, in fresh extraction sockets of the aesthetic zone of the maxilla. Materials and methods: Tapered, roughened surface implants of 4mm (n1/415) or 5mm (n1/413) diameter were placed in 27 participants (mean age: 47.1 years; range: 21–71 years) requiring an immediate replacement of single anterior maxillary teeth. Provisional screw-retained all-ceramic crowns were placed within 4 h following optical impressions. At 8 weeks (baseline), definitive screw retained all-ceramic crowns were placed in occlusion.

RESULTS: Twenty-six of the 28 implants met the inclusion criteria at surgery. Marginal bone levels revealed bone gain between surgery and baseline, and between baseline and 1 year of 0.2mm (SD 0.75) and 0.78mm (SD 2.45). Mean mid-buccal mucosal margins showed gains of 0.2mm (SD 0.44). Prosthodontic maintenance and the aesthetics of the screw-retained implant crowns were facilitated by the external hex 121-angled prosthodontic platform on the novel implant design, re-orientating the access cavity to the palatal or occlusal surfaces. All-ceramic implant crowns showed a high success rate with low maintenance issues over 1 year.

CONCLUSION: Tapered, roughened-surfaced implants with a novel 121-angled prosthodontic platform immediately placed in fresh extraction sockets, immediately restored with provisional crowns and subsequent definitive crowns at 8 weeks were successful for 1 year.

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Off-axis implant placement for anatomical considerations using the co-axis implant

Gregori M Kurtzman, Douglas F Dompkowski, Brian A Mahler and Dale G Howes Inside Dentistry - May 2008

Implants placed at positions off the vertical axis have been referred to as ‘tilted implants’ or ‘off-axis fixtures’. These may be placed to avoid various anatomical structures or to eliminate the need for bone grafting and nerve repositioning procedures.

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Comparative 3D finite element stress analysis of straight and angled wedge-shaped implant designs

Estevam Barbosa las Casas, Carlos Alberto Cimini Jr, Luis Paulo da Silva Barra The International Journal of Oral and Maxillofacial Implants

PURPOSE: The goal of this work was to analyze the stress distribution in 2 wedge-shaped implant designs, straight and angled, by means of a 3-dimensional finite element method (FEM) stress analysis.

MATERIALS AND METHODS: A model was generated from computerized tomography of a human edentulous mandible with the implants placed in the left first molar region. The model included boundary conditions representing the muscles of mastication and the temporomandibular joint. An axial load of 100N and a horizontal load of 20 N were separately applied at the tops of the implant abutments, and system equilibrium equations were used to find each muscle intensity force based on its position and direction. The mandibular boundary conditions were modeled considering the anatomy of the supporting muscle system. Cortical and medullary bones were assumed to be homogeneous, isotropic and linearly elastic.

RESULTS: The stress analysis provided results in terms of normal maximum tensile and compressive stress fields. The stress distribution was quite similar for both designs, indicating a good performance of the angled design.

CONCLUSION: Stresses in the angled implant were in general lower than in the straight implant, and the differences between the 2 designs studied were more relevant for the vertical load. No indication was found that angled implants of the type described generate stress-induced problems compared to straight implants.

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Surgical modifications to the Branemark Zygomaticus Protocol in the treatment of the severely resorbed maxilla: a clinical report.

Boyes-Varley, J.G., Lownie, J.F., Howes D.G., Blackbeard G.A. Int J Oral Maxillo Facial Implants 2003

PURPOSE: The Zygomaticus dental implant, designed by Nobel BioCare, was developed for the treatment of the severely resorbed maxilla. Branemark has reported an overall success rate of 97.6% with the placement of 183 implants over the last 12 years. The purpose of this article was to present a modification to the original Branemark surgical approach to achieve better access and optimal implant placement.

MATERIALS AND METHODS: There are parameters within the patient’s resorbed skeletal frame that guide the surgical placement of the currently used implant however, there are shortcomings in the current surgical protocol. This report describes a simplified surgical approach in 45 patients (77 implants) using an implant with a modified head angulation of 55 degrees and a placement appliance to assist the surgeon in placing the implant as close to the crest of the edentulous ridge as possible.

RESULTS: The placement appliance identifies accurately the anatomic constraints of the resorbed skeletal frame that limit implant placement. This, together with the modified surgical protocol, has resulted in improved access and in ideal positioning of the restorative head.

DISCUSSION: The present technique allows restorative clinicians to achieve a more ideal restorative result in the posterior maxillary alveolus using the zygomatic implant, while reducing the buccal cantilever, improving tongue space, and access for maintenance.

CONCLUSION: By placing the implant closer to the crest of the alveolar ridge using the placement appliance and an implant with a 55-degree head, the emergence of the restorative head and resultant buccal cantilever can be reduced by as much as 20%.

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A protocol for maxillary reconstruction following oncology resection using zygomatic implants

Boyes-Varley JG, Howes DG, Davidge-Pitts, KD, Branemark PI, McAlpine AJ Maxillofacial surgery, 2008

The rehabilitation of the midface after trauma or oncology resection present unique surgical and prosthodontic challenges. These structures, which are ablated by trauma or resection, supply the functions of speech, mastication and deglutition. In addition, the resultant facial deformities after resection or gunshot wounds to the face can create serious psychological and aesthetic complications for the patients. The purpose of this clinical report is to present our surgical and prosthodontic reconstructive protocol on 20 patients who underwent maxillae resection following malignancy to the head and neck region. This protocol was developed over a period of 7 years whilst treating a series of 20 maxillary resections due to oncology. These patients were rehabilitated using the Branemark Zygomatic implant or our modified Zygomatic and zygomatic oncology implants. Patients were reconstructed prosthodontically using fixed-removal over dentures or fixed prostheses, with and without separate obdurators. This treatment protocol includes a comprehensive diagnostic phase; resection surgery with immediate implant placement and temporary obduration; post resection evaluation and prosthodontic rehabilitation. Treatment periods ranged from 6 to 96 months and success was evaluated using strict clinical, radiological, aesthetic and functional criteria. Post surgical radiology was undertaken at six monthly intervals. Almost all maxillary defects resulting from anatomical disruption of the maxillo-facial complex can be particularly well rehabilitated functionally and aesthetically using this protocol in conjunction with standard implantology and fixed/fixed-removable prosthodontic principles. This protocol simplifies the rehabilitation and management of these defects by reducing surgical intervention, hospitalization, post-operative morbidity and treatment time and prosthodontic procedural complications.

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Malignant tumors of the maxilla: vital planning and real- time rehabilitation with custom-made R-zygoma fixtures and carbon-graphite fiber-reinforced polymer prostheses

Karl Ekstrand, Jan-M Hirsch Clinical implant dentistry and related research, Volume 10, Number 1, 2008

BACKGROUND: Oral cancer is a mutilating disease. Because of the expanding application of computer technology in medicine, new methods are constantly evolving. This project leads into a new technology in maxillofacial reconstructive therapy using a redesigned zygoma fixture.

PURPOSE: Previous development experiences showed that the procedure was time-consuming and painful for the patients. Frequent episodes of sedation or general anesthetics were required and the rehabilitation is costly. The aim of our new treatment goal was to allow the patients to wake up after tumor surgery with a functional rehabilitation in place.

MATERIALS AND METHODS: Stereolithographic models were introduced to produce a model from the three-dimensional computed tomography (CT). A guide with the proposed resection was fabricated, and the real- time maxillectomy was performed. From the postoperative CT, a second stereolithographic model was fabricated in permanent soft silicon.

RESULTS: The result of this projects showed that it was possible to create a virtual plan preoperatively to apply during surgery in order for the patient to wake up functionally rehabilitated.

CONCLUSION: From a quality-of-life perspective it is an advantage to be rehabilitated fast. By using new computer technology, pain and discomfort are less and the total rehabilitation is faster, which in turn reduces days in hospital and thereby total costs.

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Mandibular single-implant overdentures: a review with surgical and prosthodontic perspectives of a novel approach

Nabeel Alsabeeha, Alan G. T. Payne, Rohana K. De Silva, Michael V. Swain Clin. Oral Impl. Res. 20, 2009; 356–365

OBJECTIVES: To review the literature on mandibular single-implant overdentures (opposing complete maxillary dentures), and present surgical and prosthodontic perspectives of a novel approach for this treatment option.

MATERIALS AND METHODS: An electronic search through the databases of PubMed, Embase and Medline using the linked key words ‘mandibular single implant overdentures’ was performed. The search was limited to English language articles published up to August 2008. Hand searches through articles retrieved from the electronic search, peer-reviewed journals and recent conference proceedings were also conducted.

RESULTS: A limited number of reports were identified on mandibular single-implant overdentures (opposing maxillary complete dentures). They comprised of case series reports, short-term prospective trials and current randomized-controlled clinical trials. Different loading protocols with different implant systems have been used, but always with regular diameter implants. Specific anatomical and vascular dangers of the mandibular midline symphysis are identified including a novel surgical approach using a currently available short, wide diameter tapered implant. In addition, the prosthodontic rationale for using a larger attachment system (incorporating a platform switch) for mandibular single-implant overdentures is described.

CONCLUSION: The review reveals that there is a lack of published randomized clinical trials using mandibular single-implant overdentures, opposing maxillary complete dentures. Without the evidence from randomized clinical trials, routine use of this novel approach cannot be recommended, compared with using regular diameter implants and matching attachment systems.

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One-stage operative procedure using two different implant systems: A prospective study on implant overdentures in the edentulous mandible.

Tawse-Smith, A., Payne, A.G.T., Kumara, R., Thomson, W.M. Clin Implant Dent Relat Res 2001;3-4; 185-193

BACKGROUND: Evidence-based reports are needed to support the application of a one-stage surgical protocol for unsplinted implants supporting mandibular overdentures.

PURPOSE: To examine the feasibility and success of using two different dental implant systems (originally designed for two-stage operative technique) using a one-stage operative procedure in patients being rehabilitated with implant supported mandibular overdentures.

MATERIALS AND METHODS: The study sample involved 24 edentulous subjects (aged 55-80 yr) randomly allocated to two different implant systems, one with a machined titanium implant surface (Steri-Oss/Nobel Biocare, Goteborg, Sweden) and the other with a roughened titanium surface (Southern Implants, Ltd., Irene, South Africa). Two unsplinted implants to support implant overdentures were placed in the anterior mandible of all patients, using a standardized one-stage surgical and prosthodontic procedure. Primary stability and bicortical anchorage of the implants was mandatory before healing abutments were connected at the time of implant placement. Implant overdentures and their respective matrices were inserted following a standard 12-week healing period. Data relating to mobility tests, radiographs, and peri-implant parameters were documented at 12, 16, and 52 weeks after surgery.

RESULTS: A success rate of 95.8% for the Steri-Oss and 100% for the Southern Implants was found, without any statistically significant differences in the marginal bone loss. Significant changes in Periotest values were observed for both types between 12 and 52 weeks (p < .001). Minor changes were observed in the peri-implant parameters evaluated.

CONCLUSIONS: These preliminary findings show a successful application of this one-stage approach for unsplinted implants supporting mandibular overdentures with Steri-Oss and Southern Implant Systems.

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Mandibular overdentures: Comparative evaluation of prosthodontic maintenance of three different implant systems during the first year of service

Watson.G.K., Payne,A.G.T., Purton, D.G.,Thomson W.M. Int J Prosthodon 2002; 15: 259-266.

PURPOSE: The purpose of this study was to evaluate the professional time required for the prosthodontic maintenance events of mandibular implant overdentures during the first year of service using three different implant systems (ITI, Steri-Oss, or Southern).

MATERIALS AND METHODS: Seventy-two mandibular implant overdenture patients were allocated to three equal groups, each treated with a different implant system. Data on prosthodontic maintenance events during the first year were categorized and analyzed according to professional time allocation per procedure.

RESULTS: Sixty-eight percent of the patients, regardless of implant system, required prosthodontic maintenance in the first year, most commonly for the matrices. The Southern Implants matrices required less maintenance than those of Steri-Oss or ITI (P < .05).Additional overdenture maintenance was required by 28% of patients, irrespective of implant system. When all categories of prosthodontic maintenance were combined, there were no differences between implant groups. Evaluation of overall prosthodontic success using six-field tables revealed statistically significant differences between the three implant systems, with more ITI and Steri-Oss patients than Southern Implants patients requiring overdenture retreatment (repair).

CONCLUSION: During the first year of service, the matrix maintenance requirements of Southern Implants were significantly lower than those of the ITI or Steri-Oss groups; this was reflected in the number of retreatment (repair) categories recorded. Although the three systems did not differ significantly for overall prosthodontic maintenance, both the Steri-Oss and the ITI titanium matrices showed problems of clinical significance.

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Primary stability measurements of single implants in the midline of the edentulous mandible for overdentures

Nabeel H. M. Alsabeeha, Rohana K. De Silva, W. Murray Thomson, Alan G. T. Payne Clinical Oral Implants Research

OBJECTIVES: To determine the primary stability of the Southern wide diameter (8mm) implants, Neoss regular diameter (4mm) implants, and Southern regular diameter (3.75mm) implants placed in the midline of edentulous mandibles for single-implant overdentures. Variables related to host site and implant characteristics were investigated to determine their influence on the primary stability of the implants.

MATERIALS AND METHODS: A total of 36 implants were placed in the midline symphysis of the edentulous mandibles of 36 participants. Their primary stability was then measured using the magnetic Osstell mentor device. Analysis of variance (ANOVA) was used to compare the mean implant stability quotient (ISQ) scores with one-way ANOVA for multiple comparisons.

RESULTS: The highest measurement (ISQ) of primary stability was for the Southern 8mm wide diameter implants (84.8, SD9.8), followed by the Neoss 4mm regular diameter (82.3, SD4.8) implants and the Southern 3.75mm regular diameter implants (75.3, SD8.4), respectively. The Southern 3.75mm regular diameter implants had a significantly lower mean ISQ value than the same system 8mm wide diameter (P1/40.004) and the Neoss 4mm regular diameter implants (P1/40.03). No significant differences were observed between the 8mm and the 4mm diameter implants (P40.05).

CONCLUSIONS: Host-site variables such as age, gender, bone volume, and quality do not appear to influence the primary stability of the implants. No clear correlation was established between ISQ values and implant diameter.

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Scanning Electron Microscopy Observations of Failures of Implant Overdenture Bars: A Case Series Report

J. Neil Waddell, Alan GT Payne, Michael V. Swain, Jules A. Kieser Clinical Implant Dentistry and Related Research, Volume 12, Number 1, 2010

BACKGROUND: Soldered or cast bars are used as a standard of care in attachment systems supporting maxillary and mandibular implant overdentures. When failures of these bars occur, currently there is a lack of evidence in relation to their specific etiology, location, or nature.

PURPOSE: To investigate the failure process of a case series of six failed soldered bars, four intact soldered bars, and one intact cast milled bar, which had been supporting implant overdentures.

MATERIALS AND METHODS: A total of 11 different overdenture bars were removed from patients with different configuration of opposing arches. A failed bar (FB) group (n = 6) had failed soldered overdenture bars, which were recovered from patients following up to 2 years of wear before requiring prosthodontic maintenance and repair. An intact bar (IB) group (n = 5) had both soldered bars and a single cast milled bar, which had been worn by patients for 2 to 5 years prior to receiving other aspects of prosthodontic maintenance. All bars were examined using scanning electron microscopy to establish the possible mode of failure (FB) or to identify evidence of potential failure in the future (IB).

RESULTS: Evidence of a progressive failure mode of corrosion fatigue and creep were observed on all the FB and IB usually around the solder areas and nonoxidizing gold cylinder. Fatigue and creep were also observed in all the IB. Where the level of corrosion was substantial, there was no evidence of wear from the matrices of the attachment system. Evidence of an instantaneous failure mode, ductile and brittle overload, was observed on the fracture surfaces of all the FB, within the solder and the nonoxidizing gold cylinders, at the solder/cylinder interface.

CONCLUSION: Corrosion, followed by corrosion fatigue, appears to be a key factor in the onset of the failure process for overdenture bars in this case series of both maxillary and mandibular overdentures. Limited sample size and lack of standardization identify trends only but prevent broad interpretation of the findings.

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Attachment systems for mandibular single-implant overdentures: An in-vitro retention force investigation on different designs

Nabeel Alsabeeha, Michael V Swain, Alan GT Payne International Journal of Prosthodontics 2010; 23: 160-166

PURPOSE: The aim of this study was to investigate the retentive force of six different attachment systems used for mandibular singe-implant overdentures, including two prototype large ball attachment designs.

MATERIALS AND METHODS: Two prototype ball attachments of larger dimensions (7.9 and 5.9mm) and four commercially available ball and stud attachments of standard dimensions (2.25 and 4.0mm) were evaluated on three identical test casts resembling and edentulous mandible with severe residual ridge resorption. Five samples from each attachment system (n=30) were connected to three different implants (8.0mm wide diameter, 3.75mm regular diameter and 4.0mm regular diameter. An Instron testing machine with a computer software package was used to deliver a vertical dislodging force at a cross-head speed of 50mm/min to each overdenture sample from the anterior direction. A total of 300 pull tests were conducted (50 per attachment system).The maximum load (retentive force) required to separate each overdenture from the supporting implant was then measured.

RESULTS: The highest retentive force (36.97+/- 2.23N) was achieved with the 7.9mm prototype ball attachment design (32.06 +/- 2.59 N) the standard 2.25mm ball attachment (17.32 +/- 3.68N), Locator pink (9.40 N +/- 0.74N) and Locator blue (3.83 +/- 0.64 N).A statistically significant difference (P < .0001) was found between all attachments.

CONCLUSIONS: Attachment systems of larger dimensions provided higher retentive forces for mandibular single-implants overdentures. Further in-vitro and in vivo research is necessary to determine prosthodontic outcomes with these attachments in edentulous patients prior to their routine clinical use internationally.

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A systematic review of marginal bone loss around implants retaining or supporting overdentures

Murat Cavit Cehreli, Durdu Karasoy, Ali Murat kokat, Kivanc Akca, Steven Eckert International Journal for Oral maxillofacial Implants 2010; 25:266-277

PURPOSE: To evaluate, through a systematic review of the literature, the effects of implant design and attachment type on marginal bone loss in implant-retained/supported overdentures.

MATERIALS AND METHODS: With the combined search terms “implant and overdenture”, “implant-supported overdenture”, “implant-retained overdenture” and “implant-anchored overdenture” along with specific inclusion and exclusion criteria, eligible articles between 1997 and 2008 (up to April 1) were retrieved from PubMed, EMBASE, OVID, the Cochrane Library databases, and seven journals by hand searching. Marginal bone loss values with regard to time, attachment type and implant system used were compared by Kruskal-Wallis tests. Means and standard deviations of data were combined using fixed- and random- effect models and evaluated using meta-analysis.

RESULTS: Forty-six articles were included in the analyses; data extraction and meta-analysis was able to be conducted on eight studies. Data regarding maxillary overdentures could not be analyzed statistically. Bone loss around mandibular did not seem to be influenced by implant system or attachment design (bar, ball, magnet and other types) in the first year, from 1 to < 5 years, and even after 5 years (P < .05).

CONCLUSIONS: Based upon a systematic review and meta-analysis of the literature that identified a total of 4,200 implants from 13 manufacturers, there was no difference in marginal bone loss around implants retaining/supporting mandibular overdentures relative to implant type or attachment designs.

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Early loading of unsplinted implants supporting mandibular overdentures using a one-stage operative procedure with two different implant systems: A 2-year report.

Tawse-Smith, A., Payne, A.G.T., Kumara, R., Thomson, W.M. Clin Implant Dent Relat Res 2002;4: 33-42

This article is a 2 year follow-up from article 12.

BACKGROUND: Step-wise reduction in loading protocols is necessary to evaluate early loading of implants with mandibular overdentures.

PURPOSE: To compare the success rates of two different dental implant systems following conventional or early loading protocols in patients being rehabilitated with mandibular overdentures.

RESULTS: There was no statistically significant difference in the success rates of the two systems in either control or test groups. At the 2-year evaluation, a success rate was found of 87.5% and 70.8% for the control and test Steri-Oss groups, respectively, and 83.3% and 100% for the control and test Southern Implants groups were observed. For the Steri- Oss groups, eight implants were lost at an early stage: seven in the test group and one in the control group. For the Southern Implants control and test groups, no failures were seen at any time interval. There were no significant differences in marginal bone loss, Periotest values, and peri- implant parameters between implant systems or between any of the control or test groups.

CONCLUSIONS: Early loading, with step-wise reductions in loading protocols, of unsplinted machined Steri-Oss and roughened Southern Implants fixtures with mandibular overdentures is possible for up to 2 years.

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Immediate loading of 190 endosseous dental implants: a prospective observational study of 40 patient treatments with up to 2-year data

Nikellis, I., Levi, A., Nicolopoulos, C. Int J Oral Maxillofac Implants. 2004 Jan-Feb; 19(1):116-23.

PURPOSE: The present study was undertaken to determine the feasibility of using primary stability as a predictor of implant success in patients whose implants were immediately loaded.

MATERIALS AND METHODS: The study included 40 patients, in whom a total of 190 Southern implants were placed, 102 in maxillary sites and 88 in mandibular sites. All were loaded within 72 hours of placement. Sixteen patients were completely edentulous in the mandible and/or the maxilla. The remaining 24, who were partially edentulous, received fixed partial dentures or single-implant restorations. All of the definitive implant restorations were screw retained. The criterion for loading was clinical judgment of primary stability, verified by a «screw test.» Impressions were made after implant placement to facilitate the fabrication of a laboratory- made heat-processed provisional restoration from acrylic resin. Following a 4-month period for osseointegration and soft tissue healing, definitive fixed prostheses were fabricated.

RESULTS: There were no surgical complications. After 1 to 2 years, all 190 implants had survived and were considered 100% successful, as determined by independent testing of mobility and radiographic evidence of osseointegration. In 4 patients, fracture of the provisional restoration occurred during the healing period.

DISCUSSION: Clinical research has shown that immediate loading is a viable treatment modality. The favorable success rate reported in this study for rough-surfaced implants suggests that adherence to a protocol, an important parameter of which is primary stability above 32 Ncm, can lead to osseointegration.

CONCLUSION: The results of this limited investigation suggest that patients who are partially or completely edentulous may be immediately restored with implants and fixed provisional restorations, provided that the dental implants are adequately stable immediately after their surgical placement. This alternative therapeutic approach did not appear to affect the up-to-2-year survival of the implants in this patient population.

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Implant Protocol in the treatment of the severely resorbed maxilla

Howes, D.G., Boyes-Varley, J.G., Lownie, J.F., The Zygomatic SADJ 2003; 58:3; 106-114

The zygomaticus dental implant, designed by Nobel BioCare, was developed primarily for the treatment of the severely resorbed maxilla. Branemark has reported an overall success rate of 97.6% with the placement of over 200 zygomatic implants during the period 1989 to 2001.There are well-defined characteristics within the patient’s resorbed skeletal frame which guide the surgical placement of the zygomatic implant, thus determining whether the surgeon should use an implant with a 45o or 55o angulated head. This allows implant-supported restoration of the resorbed maxilla with a fixed cross arch prosthesis in the maxilla without a bone graft to the posterior maxilla. The use of a modified head angulation of 55o, with implant placement as close to the crest of the edentulous ridge as possible, allows restorative clinicians to achieve an ideal restorative position in the posterior maxilla. The use of a zygomatic implant with a 55o head reduces the buccal cantilever by 20%.

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Early functional loading of unsplinted roughened surface implants with mandibular overdentures 2 weeks after surgery

Payne, AG, Tawse-Smith, A, Thompson, WM, Kumara, R. Clin Implant Dent Relat Res. 2003; 5 (3):143-53. PMID: 14575630

BACKGROUND: Before early functional loading of unsplinted implants with mandibular overdentures can become widespread, more clinical studies are needed to investigate the success of the approach.

PURPOSE: To evaluate the success rates of two types of roughened titanium surface implants with early 2-week functional loading of paired mandibular interforaminal implants with overdentures.

MATERIALS AND METHODS: Random allocation divided 24 strictly selected edentulous participants into two groups, with each group to receive a different implant system (ITI Dental Implant System, Straumann AG, Walden- burg, Switzerland; or Southern Implant System, Southern Implants, Irene, South Africa). Two implants were placed in the anterior mandible of all participants using one-stage standardized surgical procedures. Previously constructed conventional mandibular dentures (opposing maxillary complete dentures) were temporarily relined and worn by the participants for the first 2 weeks; participants used a soft diet. Two weeks after implant surgery and following some mucosal healing, the mandibular dentures had the tissue conditioner removed and the appropriate matrices included for an unsplinted prosthodontic design.

RESULTS: No implant from either group was lost. Resonance frequency analysis (RFA) indicated higher primary stability at surgery for the Southern group than for the ITI group, with a statistically significant difference between the groups throughout the study period. The drop in RF values between surgery and 6 weeks was significant and was greater for the Southern group. RFA also indicated stabilized osseointegration between 6 to 12 and 12 to 52 weeks, with no participant showing any decrease in those values over time. Participants with type 3 bone showed a significant improvement in RF values between 12 and 52 weeks, eventually matching those of participants with type 2 bone. There were no significant differences in marginal bone loss, peri-implant parameters, or prosthodontic maintenance between the groups over the study period.

CONCLUSIONS: Using only strict patient selection criteria, 1-year follow- up data indicate that early functional loading of ITI and Southern implants with mandibular two-implant overdentures is possible as early as 2 weeks after implant surgery.

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One-stage surgery and early loading of three implants for maxillary overdentures: a 1-year report

Payne, A.G., Tawse-Smith, A., Thomson, W.M., Duncan, W.D., Kumara, R. Clin Implant Dent Relat Res. 2004; 6(2):61-74

This article uses the 3.25mm diameter implant under extremely demanding conditions.

BACKGROUND: Maxillary implant overdentures opposing mandibular two-implant overdentures are an underused treatment option for edentulous patients. Fewer implants, simple surgery, and short healing periods may increase patients’ acceptance of this treatment concept.

PURPOSE: To determine implant success, after overdenture loading, of three narrow-diameter roughened-surface implants placed in edentulous maxillas, using a one-stage surgical procedure, a 12-week healing period, and opposing mandibular two-implant overdentures.

MATERIALS AND METHODS: Forty edentulous participants with mandibular two-implant overdentures were allocated to two groups with similar implant systems. Each group had three narrow-diameter roughened-surface implants placed into their edentulous maxillas in a one-stage surgical procedure. Standardized intraoral radiography and implant stability tests were performed sequentially at surgery, at 12 weeks (prior to loading), and at 64 weeks (after 1 year of loading with maxillary overdentures).

RESULTS: One hundred seventeen implants were placed in 39 participants. After 1 year of loading, 15 implants had failed in 11 patients, 4 implants have been ‘put to sleep’ in 3 patients, and 1 patient has died. Data on marginal bone loss and resonance frequency analysis showed no significant differences between the implant systems. The mean marginal bone loss was 1.30 mm (+/- 0.44 mm) from surgery to 12 weeks and 0.32 mm (+/- 0.48 mm) between 12 and 64 weeks with loading. The mean implant stability quotient and resonance frequency values showed a statistically significant improvement over time, at 56.05 (5,891 Hz), 57.54 (5,981 Hz), and 60.88 (6,167 Hz) at surgery, 12 weeks, and 64 weeks, respectively. The overall success rate for all implants combined was 81%, and the cumulative survival rate was 84.61%.

CONCLUSION: In patients with mandibular two-implant overdentures, three narrow-diameter roughened-surface implants can be placed in the edentulous maxilla, using a one-stage surgical procedure, and can be loaded within 12 weeks with overdentures for 1 year.

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Immediately restored, single-tapered implants in the anterior maxilla: prosthodontic and aesthetic outcomes after 1 year

Hall J.A., Payne A.G., Purton D.G.,Torr B, Duncan W.J., De Silva R.K. Clin Implant Dent Relat Res. 2007 Mar;9(1):34-45

BACKGROUND: Conventional implant protocols advocate a two-stage technique with a load-free, submerged healing period. Recent studies suggest that immediate restoration of single implants may be a viable treatment option.

PURPOSE: The purpose of this study was to evaluate prosthodontics and aesthetic peri-implant mucosal outcomes of immediately restored, Southern single-tapered implants in the anterior maxilla after 1 year.

MATERIALS AND METHODS: Participants (mean age: 43.25 years; range: 23-71 years) satisfying specified inclusion criteria were randomly allocated to conventional two-stage restoration (control group; n=14) and immediate restoration groups (test group; n =14) in a randomized controlled clinical trial. Tapered, roughened-surface Southern implants were placed using a standardized technique, and implant level bone impressions were made. Provisional screw-retained crowns, out of occlusion, were placed at second-stage surgery after 26 weeks for the conventional restoration group, and within 4 hours of implant placement for the immediate restoration group. Both groups had definitive screw- retained metal-ceramic crowns placed in occlusion 8 weeks later. Peri- implant mucosal response and papilla index were recorded 4 weeks after definitive crown placement to allow for mucosal maturation and at 1 year. Prosthodontic and aesthetic outcomes were assessed using established criteria.

RESULTS: There were no significant differences within, or between, the control and test groups for age, gender, bone quality or quantity, implant stability measurements at surgery, or implant length. There were no significant differences in the implant success rate as determined by radiographic bone loss and stability tests after 1 year. There were no significant differences in prosthodontic maintenance, peri-implant mucosal response, and papilla index between the two groups over 1 year.

CONCLUSIONS: Tapered, roughened-surface implants immediately restored with single provisional crowns at surgery and definitive crowns 8 weeks later were as prosthodontically and aesthetically successful as conventionally restored two-stage implants during the first year of service. Restoring single implants immediately with screw-retained crowns is an efficient procedure, but the short-term outcome is by no means superior to a conventional two-stage approach.

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Marginal Bone Loss with Mandibular Two-Implant Overdentures Using Different Loading Protocols and Attachment Systems: 10- Year Outcomes

Sunyoung M, Andrew Tawse-Smith, W. Murray Thomson, Alan G.T. Payne The International Journal of Prosthodontics 2010;23:321–332

PURPOSE: The aim of this study was to evaluate long-term marginal bone levels for two unsplinted implants supporting mandibular overdentures using conventional and early loading protocols with different implant surfaces and attachment systems.

MATERIALS AND METHODS: A cohort of 106 edentulous participants (mean age: 65 years) was treated with mandibular two-implant overdentures opposing complete maxillary dentures. Participants were randomly allocated into three loading protocol groups using four implant systems; single-stage surgery was performed for all participants, followed by an unsplinted prosthesis using six different attachment systems. Standardized intraoral radiographs taken at baseline (loading) and over 10 years appraised marginal bone levels mesially and distally from reference points under magnification. Three calibrated examiners repeated measurements, diminishing intra- and interobserver variability. Progressive attrition of participants occurred as a result of deaths, dropouts, and emigration. Seventy-nine participants (74.5%, mean age: 72 years) were available at the 10-year recall. Differences in bone loss among different loading protocols, implant surfaces, and attachment systems were tested using chi-square and one-way analysis of variance tests.

RESULTS: Minimal, time-dependent, long-term marginal bone loss occurred with all loading protocols. Annual marginal bone loss progressed at low levels after the first year with episodes of bone loss and gain. There was stability in marginal bone levels over the long term, with the majority of remodeling occurring during the first year of function. Roughened implant surfaces may be beneficial during the early remodeling period. The amount of marginal bone loss in the first year of loading differed significantly by loading protocol and implant surface, whereas attachment system had a minor influence. Differences were not reflected in the success rates calculated using standard criteria.

The remaining participants at 10 years were classified as successful related to the criterion of marginal bone loss, irrespective of the determining criteria for success.

CONCLUSIONS: Either a 2-, 6-, or 12-week loading protocol for mandibular two-implant overdentures is possible in the long term, irrespective of the attachment system used. Minimal marginal bone loss may be attributed primarily to mandibular basal bone remaining from long-term edentulism. Revision of the current implant success criteria to offer a stricter limit is desirable.

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Conventional and immediately loaded tapered implants with screw-retained crowns.

James A., Hall, G., Alan G.T. Payne, David G. Purton, Brendan Torr International Journal of Prosthodontics 2006; 19: 17-19

PURPOSE: Surgical, prosthodontic and esthetic outcomes of conventional and immediately loaded, single, tapered, roughened-surface Southern implants in the anterior maxilla that were restored with screw-retained crowns were compared over 1 year.

MATERIALS AND METHODS: Standardized surgical and prosthodontic procedures were followed and accepted criteria were used for assessments.

RESULTS: There were no significant differences within or between the control and test groups for age, gender, bone quality or quantity, implant stability measurements at surgery, or implant length.

CONCLUSION: After 1 year, the implants that had been immediately loaded with single provisional crowns at surgery and definitive crowns 8 weeks later were as successful as conventionally loaded 2-stage implants.

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Interventions for replacing missing teeth: different times for loading dental implants (Cochrane review)

Esposito M, Worthington HV, Coulthard P The Cochrane Library, Issue 1, 2003. Oxford: Update Software.

BACKGROUND: To minimize the risk of implant failure, osseointegrated oral implants are conventionally kept load-free during the healing period. During healing removable prostheses are used, however many patients find these temporary prostheses rather uncomfortable and it would be beneficial if the healing period could be shortened without jeopardizing implant success. Nowadays immediate and early loaded implants are commonly used in mandibles of good bone quality. It would be useful to know whether there is a difference in success rates between immediately or early loaded implants compared with conventionally loaded implants.

OBJECTIVES: To test the null hypothesis of no difference in the clinical performance between osseointegrated implants loaded at different times one year after loading.

SEARCH STRATEGY: The Cochrane Oral Health Group Trials Register, The Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE were searched. Hand searching included several dental journals. Authors of all identified trials and 55 oral implant manufacturers were contacted to find unpublished RCTs. The last electronic search was conducted on 8 May 2002.

SELECTION CRITERIA: All RCTs of root-form osseointegrated oral implants having a follow-up of one year comparing the same osseointegrated root-form oral implants loaded at different times.

DATA COLLECTION AND ANALYSIS: Data were independently extracted, in duplicate, by two reviewers. Authors were contacted for details of randomization and withdrawals and a quality assessment was carried out. The Cochrane Oral Health Group’s statistical guidelines were followed.

MAIN RESULTS: Only three RCTs were identified and two trials including 68 patients in total were suitable for inclusion in this review. Implants have been either immediately loaded after insertion (two to three days), early loaded (six weeks) or conventionally loaded (three to eight months) in edentulous mandibles of adequate bone quality and shape. On a patient, rather than per implant basis, there were no statistically significant differences for prosthesis failures, implant failures and marginal bone loss on intra-oral radiographs.

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Immediate placement or immediate restoration/loading of single implants for molar tooth replacement: A systematic review and meta-analysis

Momen A. Atieh, Alan GT Payne, Warwick J. Duncan, Rohana K. de Silva, Mary P. Cullinan International Journal of Oral Maxillofacial Implants 2010: 25: 401-415

PURPOSE: This systematic review and meta-analysis assessed the survival of immediately placed single implants in fresh molar extraction sites and immediately restored/loaded single molar implants in healed molar sites.

MATERIALS AND METHODS: A search of the main electronic databases, including the Cochrance Oral Health Group’s Trials Register, was conducted up to November 1, 2008. The meta-analysis was prepared in accordance with the guidelines of the Academy of Osseointegration Workshop on the State of the Science on Implant Dentistry. The data were analyzed with statistical software.

RESULTS: For immediately placed molar implants, nine studies describing 1013 implants were included to support a survival rate of 99,0%. There were no significant differences between immediate and delayed loading/restoration in molar sites (relative risk of 0.30, 95% confidence interval 0.05 to 1.61; P=.16_. For immediate restoration/loading of single implants in healed molar sites, seven studies with 188 single implants were identified. In this case, the implant survival rate was 97.9%, with no difference between immediate and delayed loading (relative risk of 0.30, 95% confidence interval 0.33 to 27.16; P=.33). Favorable marginal bone level changes in the immediate loading group were detected at 12 months (mean difference of -0.31, 95% confidence interval: -0.53 to -0.096; P=0.005).

CONCLUSIONS: The protocols of immediate placement and immediate restorations/loading of single implants in mandibular molar regions showed encouraging results.

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Marginal Bone Loss with mandibular Two-implant overdentures using different loading protocols: A systematic literature review

Sunyong Ma,Alan GT Payne International Journal of Prosthodontics, 2010; 23:117-126

PURPOSE: Mandibular two-implant overdentures opposing conventional complete maxillary denture service. Monitoring marginal bone loss around implants is regarded as the most important criteria in determining the success of implants. The aim of this systematic literature review was to critically evaluate the literature on short- and long-term marginal bone loss associated with mandibular two-implant overdentures using different loading protocols.

MATERIALS AND METHODS: The MEDLINE, EMBASE and PubMed (using medical subject headings) databases were searched using the restriction of articles found, as well as from early online articles. Reviewed studies were those on two oral implants supporting mandibular overdentures with different loading protocols. Marginal bone loss was evaluated as well as the validity of using marginal bone loss measurements for determining the success of implants.

RESULTS: Twenty-five studies met the review criteria. Clinical studies involving conventional loading showed long-term results; however, early and immediate loading protocols were only in the short term. High success or survival rates of two implants supporting mandibular overdentures were reported, regardless of the loading protocol. A lack of standardization was revealed in the radiographic methods used for measuring marginal bone loss and the success criteria on which results were based. Long- term outcomes of the effect of different loading protocols on marginal bone loss were not found. Due to the wide methodological variation among the included studies, it was difficult to compare data between studies or to determine long-term marginal bone loss patterns with this treatment. For conventional two-stage and one-stage loading protocols, the range of marginal bone loss seen in the first year was 0.2 to 0.7mm and protocols, and 0.0 to 2.0mm respectively. For early loading protocols, the range was 0.0 to 0.2mm; immediate loading protocols saw a marginal bone loss of around 0.7mm in the first year.

CONCLUSIONS: Short-term findings indicate that so far, there is no detrimental effect on marginal bone levels with early and immediate loading protocols. However, to recommend these protocols in the long term for two implants supporting mandibular overdentures may be premature.

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Immediate versus early loading of two implants placed with a flapless technique supporting mandibular bar-retained overdentures: a single-blinded, randomized controlled clinical trial

Gioacchino Cannizzaro, Michele Leone, Marco Esposito European Journal of Oral Implantology 2008; 1(1):33-43

PURPOSE: To evaluate the efficacy of immediate loading versus early at 6 weeks of bar-retained mandibular overdentures supported by two implants placed with a flapless technique.

MATERIALS AND METHODS: Sixty patients were randomized: 30 to the immediately loaded group and 30 to the early loaded group. To be immediately loaded, implants had to be inserted with a minimum torque > 48Ncm. Outcome measures were prosthesis and implant failures, biological and biomechanics complications, patient satisfaction, and Implant Stability Quotient (ISQ) assessed with a resonance frequency analysis instrument.

RESULTS: Sixty implants were placed in each group. Flaps had to be raised in nine patients to check drill direction or to better visualize the area after multiple teeth extraction. Two implants in two patents did not reach the planned insertion torque and were immediately replaced by larger diameter ones. After 1 year no drop out occurred and two early loaded implants failed in two patients. There were no statistically significant differences between groups for prostheses failures, implant losses, complications, and means ISQ values; however, patients in the immediately loaded gout were significantly more satisfied than those loaded early. When comparing means ISQ values taken 6 weeks after placement with 1-year data within each group, values decreased significantly.

CONCLUSIONS: Mandibular overdentures can be successfully loaded the same day of implant placement with minimally invasive surgery, increasing patient satisfaction while decreasing treatment time and patient discomfort. No apparent advantages were seen when loading the overdentures at six weeks.

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The radiographic bone loss pattern adjacent to immediately placed, immediately loaded implants

Robert A Jaffin, Matthew Kolesar, Akshay Kumar, Satoshi ishikawa, Joseph Fiorellini International Journal of Oral Maxillofacial Implants, 2007: 22:187-194

PURPOSE: The purpose of this study was to evaluate radiographic bone levels adjacent to implants placed in fresh extraction sockets (ESs) and immediately loaded with a fixed full-arch provisional restoration compared to bone levels adjacent to implants placed in native bone (NB) under the same restorative conditions.

MATERIALS AND METHODS: Patients with a hopeless maxillary and/ or mandibular dentition had their remaining teeth extracted and 6-8 implants placed and restored within 72 hours. Radiographs were obtained at the time, 0, 3 to 6 months, and annually for 5 years. The radiographs were digitized, and the bone level changes were measured using a computer-assisted method.

RESULTS: A total of 139 implants, 42 ES and 97 NB, placed in 17 patients were evaluated. The overall results indicated that for all implants (ES+NB), 0.60 =/- 0.71mm of bone was lost after 6 months; 1.17 +/- 0.59mm of bone was lost after 18 months; 0.87 +/-0.76mm of bone was lost after 36 months; and after 1.35 +/-0.42mm of bone was lost after 60 months. When stratifying for NB vs. ES implants, it was found that for NB implants, 0.75 +/- 021mm of bone was lost after 6 months, 1.31 +/-0.91mm of bone was lost after 12 months, 1.07 +/-0.21mm of bone was lost after 36 months; and 1.45 +/- 0.49mm of bone was lost after 54 months. For ES implants, 0.14+/- 0.33mm of bone was lost after 6 months; 1.02 +/- 0.27mm of bone was lost after 12 months; 0.86 +/- 0.42mm of bone was lost after 36 months; and 1.30 +/-0.48mm of bone was lost after 54 months.

CONCLUSION: The combination of ES and NB implants can be immediately loaded with a fixed full-arch prosthesis and remain stable for greater than 5 years. The bone loss adjacent to these implants is similar to that seen surrounding those placed and restored using traditional protocols.

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A 5-year follow-up comparative analysis of the efficacy of various osseointegrated dental implant systems: a systematic review of randomized controlled clinical trials

Esposito M., Grusovin, M.G., Coulthard, P.,Thomsen, P., Worthington, H.V. Int J Oral Maxillofac Implants. 2005 Jul-Aug;20(4):557-68

PURPOSE: To test the null hypothesis that there is no difference in failure rates between various root-formed osseointegrated dental implant systems after 5 years of loading.

MATERIALS AND METHODS: A search was conducted for all randomized controlled clinical trials (RCTs) comparing different implant systems with a follow-up of 5 years. The Cochrane Oral Health Group’s Trials Register, CENTRAL, MEDLINE, and EMBASE were searched. Several dental journals were also searched by hand. Written contacts were established with authors of the identified RCTs and with more than 55 oral implant manufacturers and personal contacts to identify unpublished RCTs. No language restriction was applied. The last electronic search was conducted on February 1, 2005. Screening of eligible studies, quality assessment, and data extraction were conducted in duplicate. Results were expressed as random effect models using weighted mean differences for continuous outcomes and relative risk for dichotomous outcomes with 95% confidence intervals.

RESULTS: Ten RCTs were identified. Four of these RCTs, reporting results from a total of 204 patients, were considered suitable for inclusion. Six different implant types were compared. On a per-patient rather than a per-implant basis, there were no statistically significant differences, with the exception of more marginal bone loss around early loaded Southern implants when compared to early loaded Steri-Oss implants (mean difference -0.35 mm; 95% CI -0.70 to -0.01). However, the difference disappeared in the meta-analysis.

DISCUSSION AND CONCLUSIONS: There were no clinical differences among implant systems. However, these findings are based on only 4 RCTs with few participants. More RCTs should be conducted with larger patient samples.

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A comparison of three different implant systems in the same patient

Lester du Preez, Kurt-W Butow, Wilfried Benninghof International dentistry South Africa Vol. 8 no 3

OBJECTIVES: The goal of this study was designed to test three different implant design systems in the same patient under similar conditions, for their longevity. To date many different makes of implant systems are available on the market. Many of these are based on the Branemark submergible endosseous implant. The various implants come in different designs and coatings. The coating materials include hydroxyapatite, ceramics or titanium (plasma sprayed/pure/alloy). Most of the implants are two-stage submergible units, requiring two surgical procedures for placement. Recently there has been a move towards single stage implants with the added advantage of one surgical procedure for the patient. The question as to which implant is the better one, is still open to speculation.

MATERIALS AND METHODS: Six titanium implants, three pairs of different design, were placed in the mandibles of 14 patients and evaluated over one to five years. The six implants included: Two cylindrical units (GMI, Southern Implants), two Branemark-like implants (IBS, Southern Implants), and two compression implants (OCSI[LIBS], Southern Implants of South Africa (Pty) Ltd.

RESULTS: The retention rate of the implants over the observation period was 97,2%, comparing favorably with the retention rate as published in the literature.

CONCLUSION: The success of the study proves the hypothesis that different designs of implant systems have no bearing on the longevity or functional success of the units used, and lends credence to the assumption that the design of the implant does not influence its functionality.

CLINICAL SIGNIFICANCE: Different designs of implant systems have no bearing on the longevity or functional success of the units used, and lends credence to the assumption that the design of the implant does not influence its functionality in the anterior mandible.

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A prospective study of implant-supported full-arch Yttria- stabilized tetragonal zirconia polycrystal mandibular fixed dental prostheses: Three year results

Christel Larsson, Per Vult von Steyem, Krister Nilner International Journal Prosthodontics 2010;23:364-369

PURPOSE: The development of high-strength oxide ceramic materials has led to increased interest in all ceramic fixed dental prostheses (FDPs). Success rates reported in clinical studies for all-ceramic FDPs based on high-strength oxide ceramic materials reportedly approach those of porcelain-fused-to-metal FDPs. These reconstructions, however, are still of limited size and have mainly concerned FDPS supported by natural teeth. The purpose of this study was to evaluate the clinical performance of multiunit all-ceramic FDPs supported by dental implants.

MATERIALS AND METHODS: Ten patients received mandibular yttria- stablized tetragonal zirconia polycrystal (Y-TZP) FDPs according to the Cercon technique and supported by four Astra Tech implants. Nine patients received 10-unit FDPs and one patient received a 9-unit FDP. The FDPs were cemented with Panavia F2.0 onto individual prepared titanium abutments. The FDPs were evaluated at baseline and after 12, 24 and 36 months.

RESULTS: At the 3 year follow-up, all FDPs were in use, and all patients were fully satisfied with their treatment. None of the reconstructions had fractured. Superficial chi-off fractures of the veneering porcelain were, however, observed in nine patients (34 of 99 units, 34%).

CONCLUSION: Results from this 3-year study suggest that implant- supported full-arch Y_TZP FDPs manufactured according to the Cercon technique should be viewed as a treatment alternative cautiously. A better understanding of the factors resulting in chip-off fractures is needed, together with longer follow-up tidies involving larger numbers of patients, before the material and technique can be recommended for general use.

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Fracture strength of four-unit Y-TZP FPD cores designed with varying connector diameter. An in-vitro study

C Larsson, L Holm, N Lovgren, Y kokubo, P Vult von Steyern Journal of Oral rehabilitation 2007 34: 702-709

Reported clinical success rates of all-ceramic fixed partial dentures (FDPs) made of high-strength oxide ceramics range between 82,5% and 100%. The main cause of all-ceramic FPD failure is fracture in the connector dimensions area. There is, however, no consensus on what connector dimensions are adequate. The aim of this in-vitro study was, therefore, to compare the fracture strength of four-unit Y-TZP FPD cores designed with difference connector diameters. A total of 40 four- unit FPD cores supported by end abutments and having two pontiffs were manufactured in Procera Zirconia. Five groups of FPD cores with connector dimensions of 2.0, 2.5, 3.0 3.5 and 4.0mm were produced. All FPD cores underwent a firing programme according to the manufacturer’s recommendations for the veneering porcelain, a cyclic preload, thermocycling and finally, load until fracture. Fracture strength was significantly higher for each increase in connector diameter except for the 2.0mm and 2.5mm diameters where all fractures occurred during preload. Within the limitations of this in-vitro study, a minimum diameter of 4.0mm is recommended for all-ceramic zirconia-based FPDs with long spans or replacing molars. Clinical studies are, however, needed to determine adequate connector dimensions.

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Scanning Electron Microscopy evaluation of the interfacial fit of interchanged components of four dental implant systems.

Dellow, A.G., Driessen, C.H., Nel, H.J.C. Int J of Prosthodont 1997 10; 216-221.

The introduction of the original Swedish implant system (Branemark) was followed by several alternative implant systems with implants and components that closely resembled the original design and treatment protocol. Some of these alternative systems may be interchangeable. Manufacturing variations can result in as much as 0.1 mm of space between the component parts. The implant/abutment interface fit was evaluated by scanning electron micrography for each of four implant systems, as well as interchanged components between the various systems. Results showed that certain implant system abutments are interchangeable and that the accuracy of fit meets with or exceeds the criteria set by the original Swedish system.

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Abstracts from publications in peer-reviewed journals

Contents

MAX

Co-Axis

Zygomatic

Overdentures

Loading Protocols

Comparative

Ceramic Abutments

Microgaps

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