Standard of care for the edentulous mandible: a systematic review

STATEMENT OF PROBLEM: Implant therapies have increased the range of prosthodontic options for the treatment of edentulism. Considering both dentist- and patient-mediated outcomes, a universal treatment intervention for the treatment of the edentulous mandible has not been demonstrated. PURPOSE: The purpose of this study was to test the null hypothesis that there is no single standard of care for the edentulous mandible as defined by a specific treatment modality. MATERIAL AND METHODS: A review of the literature was undertaken seeking evidence of a superior intervention for the treatment of the edentulous mandible. A search of the English language peer-reviewed literature was completed using Medline and Google Scholar for the period from 1995 to 2005, focusing on evidence-based research. This was supplemented with a hand search of selected dental journals and textbooks. Longitudinal retrospective studies, longitudinal prospective studies, longitudinal experimental clinical studies, nonrandomized controlled studies, and randomized controlled clinical trials were included for review using a general linear hierarchical classification of studies. Articles that did not focus exclusively on treatment interventions for mandibular edentulism or on the effects of such therapies on the patient were excluded from further evaluation. The search period included articles that were published before the criteria for evidence-based literature were established, but this was not necessarily used to exclude an article. The last search was conducted on September 25, 2005. RESULTS: The literature demonstrates that the functional demands of edentulous patients are highly variable and that patient treatment responses are individual, vary significantly, and are influenced by psychosocial forces. The literature further demonstrates that patient acceptance of specific treatment modalities is modified by social and cultural influences, financial means, and adaptive capacity. Additionally, patient acceptance of a particular treatment modality is influenced by the educational background, knowledge, and experience of the dental health care provider, as well as by a host of other socioeconomic, regional, cultural, age, and gender influences. CONCLUSIONS: Within the limits of this review, there is no evidence for a single, universally superior treatment modality for the edentulous mandible. Better designed, long-term studies are required to further explore differences in patient acceptance to each treatment intervention for the edentulous mandible.     

Maxillary Overdentures Supported by Anteriorly or Posteriorly Placed Implants Opposed by a Natural Dentition in the Mandible: A 1‐Year Prospective Case Series Study

Background: For maxillary overdenture therapy, treatment guidelines are missing. There is a need for longitudinal studies. Purpose: The purpose of this 1‐year prospective case series study was to assess the treatment outcome of maxillary overdentures supported by six dental implants opposed by natural antagonistic teeth in the mandible. Materials and Methods: Fifty patients were treated with a maxillary overdenture supported by six dental implants, either placed in the anterior region (n = 25 patients) or in the posterior region (n = 25 patients). Items of evaluation were the following: survival of implants, condition of hard and soft peri‐implant tissues, and patients' satisfaction. Results: One‐year implant survival rate was 98% in the anterior group and 99.3% in the posterior group. Mean radiographic bone loss in the anterior and posterior groups after 1 year of loading was 0.22 and 0.50 mm, respectively. Mean scores for plaque, calculus, gingiva, bleeding, and pocket probing depth were low, and patients' satisfaction was high, with no differences between the groups. Conclusion: Six dental implants placed in either the anterior region or the posterior region of the edentulous maxilla, connected with a bar, and opposed by antagonistic teeth in the mandible supply a proper base for the support of an overdenture.     

Which prosthetic treatment concepts present a reliable evidence-based option for the edentulous maxilla related to number and position of dental implants?

Purpose: The objective of this systematic review, serving as a basis for an expert consensus conference, was to answer the following questions: Which prosthetic treatment concept related to implant number and position presents a reliable evidence-based option for the edentulous maxilla? How many implants should be installed and what kind of implant prosthesis works most efficiently related to this number? Previously, these questions could not be answered adequately, although several meta-analyses considering the respective issues have been published. However, some reports included study designs with a low level of evidence (e.g. retrospective) and observation periods of less than 3 years. In this systematic review, stricter inclusion criteria were used in an attempt to reach a higher level of evidence. Materials and methods: An electronic MEDLINE (PubMed) search was conducted to identify all relevant studies concerning either fixed or removable implant prosthetics. The most important inclusion criteria were: the trial had to be an randomised controlled trial (RCT) or at least prospective (minimum observation period of 3 years); endosseous implants were examined; details on implant and/ or prosthesis survival were provided. Results: The search revealed 988 abstracts of possible relevance. Twenty-nine publications met the inclusion criteria. In total, 7028 implants and 1130 patients were observed. Because of the heterogeneity among the included studies, a statistical analysis of the extracted data was questionable. Conclusions: Owing to different study protocols (with different implant systems, loading protocols, surgical procedures, designs of supraconstructions, etc.), varying statistical methods, and often missing information of the included studies, highly reliable conclusions are hardly possible. Welldesigned RCTs are needed to provide scientifically validated prosthetic treatment protocols.     

Tilted Implants for the Rehabilitation of Edentulous Jaws: A Systematic Review

Purpose: The aim of this review was to evaluate the survival rate of upright and tilted implants supporting fixed prosthetic reconstructions for the immediate rehabilitation of partially and fully edentulous jaws, after at least 1 year of function. Materials and Methods: An electronic search of databases plus a hand search on the most relevant journals up to December 2009 was performed. The articles were selected using specific inclusion criteria, independent of the study design. Results: The literature search yielded 347 articles. A first screening based on the title and abstract identified 25 eligible studies. After full‐text review of these studies, 10 articles were selected for analysis. Seven were prospective single‐cohort studies and three had a retrospective design. A total of 462 patients have been rehabilitated with 470 immediately loaded prostheses (257 in the maxilla, 213 in the mandible), supported by a total of 1,992 implants (1,026 upright and 966 tilted). Twenty‐five implants (1.25%) failed in 20 patients within the first year. All failures except one occurred in the maxilla. No significant difference in failure rate was found between tilted and upright implants, nor between maxillary and mandibular implants. No prosthesis failure was reported. Limited peri‐implant bone loss was reported with no difference between upright and tilted implants. Full patients' satisfaction for function, phonetics, and esthetics was reported in three studies, based on questionnaires. Conclusions: The use of tilted implants to support immediately loaded fixed prostheses for the rehabilitation of edentulous jaws can be considered a predictable technique, with an excellent prognosis in the short‐medium term. However, randomized long‐term trials are needed to determine the efficacy of this surgical approach.     

Is flapless implant surgery a viable option in posterior maxilla? A review

This article reviews the literature on the outcome of flapless surgery for dental implants in the posterior maxilla. The literature search was carried out in using the keywords: flapless, dental implants and maxilla. A hand search and Medline search were carried out on studies published between 1971 and 2011. The authors included research involving a minimum of 15 dental implants with a follow-up period of 1 year, an outcome measurement of implant survival, but excluded studies involving multiple simultaneous interventions, and studies with missing data. The Cochrane approach for cohort studies and Oxford Centre for Evidence-Based Medicine were applied. Of the 56 published papers selected, 14 papers on the flapless technique showed high overall implant survival rates. The prospective studies yielded 97.01% (95% CI: 90.72-99.0) while retrospective studies or case series illustrated 95.08% (95% CI: 91.0-97.93) survival. The average of intraoperative complications was 6.55% using the flapless procedure. The limited data obtained showed that flapless surgery in posterior maxilla areas could be a viable and predictable treatment method for implant placement. Flapless surgery tends to be more applicable in this area of the mouth. Further long-term clinical controlled studies are needed.     

Mandibular complete denture versus single‐implant overdenture: a systematic review of patient‐reported outcomes

The single‐implant mandibular overdenture (SIMO) has been proposed as an alternative for edentulous patients who are poorly adapted to their dentures due to low retention and stability of the conventional mandibular complete denture (CD). However, there is a lack of evidence regarding the effectiveness of SIMO, which can be measured by examining patient perception of treatment effects. The aim of this systematic review was to assess the comparative results of CD and SIMO treatments using patient‐reported outcome measures. A literature search was carried out in PubMed, Scopus and Cochrane Central databases. The search included studies published up to July 2017. The focus question was: ‘Do single‐implant mandibular overdentures improve patient‐reported outcomes compared to conventional complete dentures in edentulous patients?’ Eligible studies were randomised clinical trials (RCT) and prospective studies. After initial screening for eligibility and full‐text analysis, 11 studies were included for data extraction and quality assessment (five parallel‐group RCTs, two crossover RCTs and four prospective studies). All studies reported marked improvement in satisfaction with the dentures and quality of life measures after SIMO treatment, irrespective of variations in implant treatment protocols and retention systems. Methodological considerations revealed a lack of evidence from RCTs on the comparative effectiveness of the two treatment strategies. Hence, although available evidence suggests considerable improvement in patient‐reported outcomes following the insertion of a single implant to retain a mandibular denture, further well‐designed comparative studies between SIMO and CD are required to improve the level of evidence and to support the indication of SIMO treatment in routine practice.     

Current ceramic materials and systems with clinical recommendations: a systematic review

STATEMENT OF PROBLEM: Developments in ceramic core materials such as lithium disilicate, aluminum oxide, and zirconium oxide have allowed more widespread application of all-ceramic restorations over the past 10 years. With a plethora of ceramic materials and systems currently available for use, an overview of the scientific literature on the efficacy of this treatment therapy is indicated. PURPOSE: This article reviews the current literature covering all-ceramic materials and systems, with respect to survival, material properties, marginal and internal fit, cementation and bonding, and color and esthetics, and provides clinical recommendations for their use. MATERIAL AND METHODS: A comprehensive review of the literature was completed seeking evidence for the treatment of teeth with all-ceramic restorations. A search of English language peer-reviewed literature was undertaken using MEDLINE and PubMed with a focus on evidence-based research articles published between 1996 and 2006. A hand search of relevant dental journals was also completed. Randomized controlled trials, nonrandomized controlled studies, longitudinal experimental clinical studies, longitudinal prospective studies, and longitudinal retrospective studies were reviewed. The last search was conducted on June 12, 2007. Data supporting the clinical application of all-ceramic materials and systems was sought. RESULTS: The literature demonstrates that multiple all-ceramic materials and systems are currently available for clinical use, and there is not a single universal material or system for all clinical situations. The successful application is dependent upon the clinician to match the materials, manufacturing techniques, and cementation or bonding procedures, with the individual clinical situation. CONCLUSIONS: Within the scope of this systematic review, there is no evidence to support the universal application of a single ceramic material and system for all clinical situations. Additional longitudinal clinical studies are required to advance the development of ceramic materials and systems.     

Sinusbodenelevation und -augmentation

Aim

It was the aim of this investigation to analyze evidence of prognosis, predictors, and risk factors concerning sinus floor elevation and augmentation (SFEA).

Materials and methods

A MEDLINE search was performed to analyze the literature published between 1990 and 2002, limited to keywords (“sinus floor elevation and dental implants”, “complications”, “success”), study type (randomized as well as clinical prospective studies, retrospective studies, reviews), and language (German or English).

Results

Of 229 publications identified, 72 met the inclusion criteria (22 prospective and 47 retrospective studies, 3 reviews). Considering the augmentation material [autogenous bone (AB), bone substitution materials (BSM), and combinations of AB and BSM], the frequency of implant loss was not significantly different (AB 8%, BSM 9%, AB + BSM 5%, p>0.09) after an observation period of 2–4 years . The average duration of the healing period was 6 months (AB) and 8 months (BSM) with simultaneous SFEA and implantation and 6–7 months (AB and BSM) for the staged approach after an average healing period of 6 months for the augmentation materials. Frequency of implant loss was not different between simultaneous and staged approaches (7–8%). Postoperative sinusitis occurred in 3–8% of the cases. Smoking, positive sinusitis history, obstructive pathoses of the nose and ostium, allergic rhino-pathoses, use of short implants (<13 mm), treatment of edentulous maxilla compared to partially edentulous maxilla, bruxism, and uncontrolled early loading of implants were identified as predictors for complications.

Conclusions

Presupposing proper consideration of indications, SFEA should be considered as an evidence-based and clinically established method for implant prosthetic rehabilitation of the atrophic posterior maxilla with an overall cumulative survival rate of 90% within an average observation period of 4 years.     

An alternative method to treat a case with severe maxillary atrophy by the use of angled implants instead of complicated augmentation procedures: a case report

Several treatment options with implants have been described for maxillary edentulous patients. Maxillary implant-supported overdentures have been shown to be a predictable, accepted treatment option for the edentulous maxilla. Patients with severe bone resorption present additional difficulties, and implant treatment in the atrophic maxilla represents a challenge. Anatomical limitations and patient desires in this case have forced the treatment to be 4 angulated implants supporting an upper overdenture. Since conventional single-retention mechanisms such as ball (O-ring), locator, or telescopes would transfer too much force to the implants, especially because of their angulation, an individual bar was fabricated. One-year follow-up of the case showed a stable peri-implant condition on bone as well as soft tissue level. Although further follow-up and higher case numbers will give more information about this treatment modality, the actual result is encouraging and can be recommended for similar cases.     

An implant-supported overdenture in an edentulous upper jaw

An implant-supported overdenture is a good alternative treatment to a conventional denture for patients with complaints about the retention and stability of their removable complete denture. These complaints more often have to do with the mandibular than the maxillary denture. Implant-supported overdentures offer better results in the mandible than in the maxilla. In cases of insujficient bone volume in the maxilla for inserting implants, maxillary sinus floor elevation using an autogenous bone graft from the oral cavity or the iliac crest may be carried out. Treatment of the edentulous maxilla by inserting 6 implants followed by manufacturing a bar-clip mesostructure and an implant-supported overdenture is the most successful, followed closely by the treatment option of inserting 4 implants and fabricating a similar mesostructure and overdenture. Aftercare by routine preventive examinations is required.     

Immediate and early implant loading protocols: a literature review of clinical studies

The purpose of this literature review is to present the outcomes of clinical studies on immediate and early loading protocols, identify shortcomings, and suggest a number of questions that still require exploration. English language clinical studies, limited to peer-reviewed journals between 1975 and 2004, were reviewed to identify treatment outcomes with these loading protocols. The data were tabulated from studies reporting on patients treated with fixed and overdenture prostheses. The former included partially edentulous patients treated with single or multi-unit prostheses. Within the limitations of this review, it can be concluded that these treatment protocols are predictable in the anterior mandible, irrespective of implant type, surface topography, and prosthesis design (success rates 90%-100%). Limited evidence for the edentulous maxilla (success rates 90%-100%) and the partially edentulous patient (success rates 93%-100%) are available, underscoring the need for further research. Studies suggest that to achieve predictable results in extraction sites, implant placement should be restricted to sites without a history of periodontal involvement (success rates 61%-100%). A number of questions require further exploration. There is a need to thoroughly investigate clinical outcomes to measure the economic benefit of these protocols and the impact of treatment on a patient's quality of life. Furthermore, more accurate long-term studies reporting on treatment protocols for separate clinical situations are required to allow meaningful comparisons.     

Indications for immediate loading of implants and implant success

Abstract: It was the aim of this review to compare the survival and success rates of immediately loaded dental implants with those of conventionally loaded dental implants, based on prospective controlled studies and prospective studies without controls. Studies on immediate loading were identified in the current literature by electronic and hand searches. Only clinical data on root-form or cylindrical threaded oral implants were included. For immediate loading of oral implants in the edentulous and partially dentate, mandible and maxilla controlled studies could be found. All of these studies were based on limited patient numbers. Therefore, definitive conclusions could not be drawn concerning survival and success rates of immediately loaded implants compared with conventionally loaded implants. The compilation of the current literature shows that prospective controlled studies as well as prospective studies without controls using several different approaches to immediate loading have demonstrated high implant survival and success rates. However, more high-level evidence-based studies are needed to demonstrate the relative merits of immediate loading compared with conventional loading in all potential applications.     

Full-arch restoration of the jaw with fixed ceramo-metal prosthesis: late implant placement

BACKGROUND: The completely edentulous patient has few treatment options in conventional dentistry. When implants are considered, treatment plans range from a 2-implant overdenture to a completely implant-supported prosthesis. Fixed prosthesis is often the preferred selection of the edentulous patient. This study assesses the 5-year cumulative survival rate of implants placed to support full-arch fixed restoration. METHODS: During 1990 to 1995, 171 implants were placed in 22 completely edentulous jaws of 20 patients. All patients were discharged wearing immediate dentures. The implants were analyzed as to the number of implants per jaw, implant location, length, and diameter. RESULTS: The 5-year cumulative survival rate was 89.9%. The mean number of implants per jaw was 7.7 for the maxilla and 8 for the mandible. In the maxilla, the preferred implant locations were the canines, centrals, laterals, and first premolars; in the mandible, they were the canines, laterals, and first molars. The mean implant length was 14.2 mm for the mandible and 13.2 mm for the maxilla. The mean implant diameter was 3.6 mm for the maxilla and 3.8 for the mandible. CONCLUSIONS: The results of the present study indicate that fixed full-arch ceramo-metal restorations can be a predictable implant treatment modality for the edentulous patient.     

快速建立无牙颌上颌骨及颅骨三维有限元模型的方法探讨

目的 探索快速建立完整无牙颌上颌骨及颅骨三维有限元模型的方法。方法对无牙颌志愿者头颅部进行多层螺旋CT扫描，利用Mimics软件和Geomagic Studio软件完成三维实体模型的重建，在此基础上通过Ansys软件建立完整无牙颌上颌骨及颅骨的三维有限元模型，并观察计算机模拟全口义齿修复后袷力作用下上颌骨的应力分布情况。结果建立了无牙颌上颌骨及颅骨的三维有限元模型。观察加载后上颌骨应力分布，发现右侧鼻底骨皮质处等效应力最大，为3．04MPa；上颌窦鼻腔开口处的前方、后方以及上颌窦颊侧壁的下方最大等效应力为1．43MPa。结论以多面体面的形式可以重建上颌骨及颅骨三维模型，运用专业造型软件可以将其转化为实体模型进行有限元建模。     

Usefulness of the Aesthetic Result as a Success Criterion for Implant Therapy: A Review

Purpose: The purpose of this study was to review the reported evaluation criteria of the aesthetic result in oral implant rehabilitation. Materials and Methods: A literature search of MEDLINE, the Cochrane Collaboration, and EMBASE was performed to retrieve studies published between January 1990 and December 2008 using the following key words: “dental implants,”“clinical trial,” and “aesthetic index” (and their synonyms). A manual search of the literature published in the same period was also carried out using the following publications: Clinical Oral Implant Research, The International Journal of Oral and Maxillofacial Implants, and The International Journal of Periodontics and Restorative Dentistry. The inclusion criteria of the published studies were the following: human clinical trial, oral implant rehabilitation, at least 10 implants, at least 6 months of follow‐up from insertion of the prosthesis, and evaluation of the aesthetic result by means of an index. Results: The literature search revealed 650 relevant bibliographic references, of which 89 were selected for further analysis. A final total of 29 articles fulfilled the inclusion criteria; these included 10 retrospective case series, 11 prospective case series, 1 retrospective controlled clinical trial, 1 prospective controlled clinical trial, and 6 randomized controlled clinical trials. In general, evaluations of aesthetic results appear only in the more recent studies and refer mostly to implant rehabilitation in the maxillary anterior zone; the index used, in most cases, was the Papilla Index of Jemt. Conclusions: Although there appears to be a growing interest in aesthetics in dental implantology, there are as yet no universally accepted evaluation criteria of the aesthetic result. Therefore, further research is necessary to establish a common, complete, and reproducible index for the evaluation of aesthetic outcome that can add in the success criteria for implant therapy in the maxillary and mandibular anterior areas.     

Implant and root supported overdentures - a literature review and some data on bone loss in edentulous jaws

PURPOSE

To present a literature review on implant overdentures after a brief survey of bone loss after extraction of all teeth.

MATERIALS AND METHODS

Papers on alveolar bone loss and implant overdentures have been studied for a narrative review.

RESULTS

Bone loss of the alveolar process after tooth extraction occurs with great individual variation, impossible to predict at the time of extraction. The simplest way to prevent bone loss is to avoid extraction of all teeth. To keep a few teeth and use them or their roots for a tooth or root-supported overdenture substantially reduces bone loss. Jaws with implant-supported prostheses show less bone loss than jaws with conventional dentures. Mandibular 2-implant overdentures provide patients with better outcomes than do conventional dentures, regarding satisfaction, chewing ability and oral-health-related quality of life. There is no strong evidence for the superiority of one overdenture retention-system over the others regarding patient satisfaction, survival, peri-implant bone loss and relevant clinical factors. Mandibular single midline implant overdentures have shown promising results but long-term results are not yet available. For a maxillary overdenture 4 to 6 implants splinted with a bar provide high survival both for implants and overdenture.

CONCLUSION

In edentulous mandibles, 2-implant overdentures provide excellent long-term success and survival, including patient satisfaction and improved oral functions. To further reduce the costs a single midline implant overdenture can be a promising option. In the maxilla, overdentures supported on 4 to 6 implants splinted with a bar have demonstrated good functional results.     

A comprehensive and critical review of dental implant prognosis in periodontally compromised partially edentulous patients

OBJECTIVES: The outcome of implant treatment in periodontally compromised partially edentulous patients has not been completely clarified. Therefore, the aim of the present study was to perform, applying a systematic methodology, a comprehensive and critical review of the prospective studies published in English up to and including August 2006, regarding the short-term (<5 years) and long-term (>or=5 years) prognosis of osseointegrated implants placed in periodontally compromised partially edentulous patients. MATERIAL AND METHODS: Using The National Library Of Medicine and Cochrane Oral Health Group databases, a literature search for articles published up to and including August 2006 was performed. At the first phase of selection the titles and abstracts and at the second phase full papers were screened independently and in duplicate by the three reviewers (I. K. K., S. K., I. F.). RESULTS: The search provided 2987 potentially relevant titles and abstracts. At the first phase of evaluation, 2956 publications were rejected based on title and abstract. At the second phase, the full text of the remaining 31 publications was retrieved for more detailed evaluation. Finally, 15 prospective studies were selected, including seven short-term and eight long-term studies. Because of considerable discrepancies among these studies, meta-analysis was not performed. CONCLUSIONS: No statistically significant differences in both short-term and long-term implant survival exist between patients with a history of chronic periodontitis and periodontally healthy individuals. Patients with a history of chronic periodontitis may exhibit significantly greater long-term probing pocket depth, peri-implant marginal bone loss and incidence of peri-implantitis compared with periodontally healthy subjects. Even though the short-term implant prognosis for patients treated for aggressive periodontitis is acceptable, on a long-term basis the matter is open to question. Alterations in clinical parameters around implants and teeth in aggressive periodontitis patients may not follow the same pattern, in contrast to what has been reported for chronic periodontitis patients. However, as only three studies comprising patients treated for aggressive periodontitis were selected, more studies, specially designed, are required to evaluate implant prognosis in this subtype of periodontitis. As the selected publications exhibited considerable discrepancies, more studies, uniformly designed, preferably longitudinal, prospective and controlled, would be important.     

Patient evaluation after treatment with maxillary implant-supported overdentures

Purpose: To evaluate and compare outcome among patients after implant overdenture treatment in the maxilla. Materials and Methods: The study sample comprised two groups of patients: group 1, in which the patients were planned for overdenture treatment, and group 2, in which the patients originally were planned for a fixed prosthesis in the maxilla but had overdenture treatment owing to implant failures, resulting in an insufficient number of implants to support a fixed prosthesis. All patients treated with maxillary implant‐supported overdentures in the Department of Prosthetic Dentistry, Central Hospital, Skövde, Sweden, between 1993 and 2002 received a questionnaire at their yearly follow‐up visit with nine questions related to their treatment. All questions had visual analogue scale response alternatives ranging from a negative to a positive opinion. Results: Nineteen patients, 10 in group 1 and 9 in group 2, completed the questionnaire, yielding a response rate of 86%. Both groups expressed a high satisfaction rate, and few regretted their choice of treatment. Patients planned for overdenture treatment (group 1) reported significantly fewer speech problems after treatment compared with those originally planned for a fixed prosthesis (group 2, p < .05). No other significant differences between the two groups were seen. Conclusion: Within the limitations of the present study, it can be concluded that maxillary implant overdenture treatment may be considered a viable option among patients with an insufficient number of implants for a fixed prosthesis.     

Treatment outcomes of fixed or removable implant-supported prostheses in the edentulous maxilla. Part II: clinical findings

STATEMENT OF PROBLEM: There is a widespread belief that maxillary overdenture prostheses are associated with a higher frequency of complications and require more maintenance than fixed implant prostheses. PURPOSE: This prospective clinical study compared the treatment outcomes of fixed and removable implant-supported restorations in the edentulous maxilla with the main emphasis on the clinician's point of view.Material and methods: Ten patients were treated with fixed screw-retained implant prostheses (group 1), and 10 patients were treated with removable implant-supported overdentures (group 2) in the edentulous maxilla. Recall was scheduled at 6-month intervals to investigate the prosthodontic treatment outcomes, including implant survival, prosthesis time until retreatment, and maintenance issues. Clinical parameters gingival index (GI), plaque index (PI), the clinical attachment level, and radiographic marginal bone levels measured, along with any biologic and mechanical complications were recorded. RESULTS: Patients were followed over a mean period of 39 months (SD=7; group 1) and 27 months (SD=10; group 2) after implant placement. Cumulative implant survival was 97.6% for group 1 and 94.4% for group 2 after an 18-month observation period. The mean time until retreatment after prostheses insertion was 23.4 months for group 1 and 19.8 months for group 2 (n.s.). In both groups, the increase over time in the radiographically investigated bone level was found to be significant. The indices given for the mucosal health and oral hygiene status (GI and PI) were highly correlated in both groups at each recall appointment, but no significant differences were found between groups 1 and 2. CONCLUSION: In groups 1 and 2, comparable prosthodontic treatment outcomes were achieved. The majority of mechanical complications could be managed chairside during recall visits and did not require additional appointments, so that the time and costs involved in providing maintenance were kept down.