Replacement of a mandibular implant-fixed prosthesis with an implant-supported overdenture to improve maintenance and care

PatientsA 69-year-old woman presented to the Osaka University Dental Hospital. She had two chief complaints, (a) food accumulation under the lower teeth and (b) poor maxillary denture retention while eating. On clinical examination the patient presented with a maxillary complete denture and fixed mandibular implant prosthesis. For preventing food accumulation under the fixed implant prosthesis and to keep the maxillary denture stable by providing posterior occlusal contact for bilaterally balanced occlusion, the use of a mandibular implant-supported overdenture with self-adjusting magnetic attachments provided a prosthetic solution for this patient. After provided the new dentures, the patient was pleased and was comfortable with the aesthetic, stability and retention of the dentures. There were no discernable clinical or radiographic changes after 1 year of use.DiscussionTo prevent food accumulation beneath the fixed implant prosthesis and maintain the stability of the maxillary denture by providing posterior occlusal contact for bilaterally balanced occlusion, a mandibular implant-retained overdenture with magnetic attachments was used to provide a prosthetic solution for this patient.ConclusionIn this clinical case, an implant-fixed prosthesis in the edentulous mandibular region was replaced into an implant-supported overdenture with considerations for (a) preventing the food accumulation beneath the lower prosthesis, (b) achieving the proper occlusion in the posterior part for maxillary denture stability and (c) ease of maintenance and care for the prostheses.     

球帽固位下颌双种植体覆盖义齿修复效果的前瞻性研究

目的 评价球帽固位的下颌双种植体覆盖义齿的临床修复效果及其修复并发症。 方法 对下颌牙槽骨重度萎缩的10例无牙颌患者,在前牙区与中线等距平行植入2枚种植体,3个月后采用球帽附着体固位方式制作下颌种植覆盖义齿。在覆盖义齿戴入后1周、1年、2年、3年进行随访,评价种植体边缘骨吸收情况、种植体周围软组织健康状况、患者满意度及义齿并发症情况。 结果 10例两球帽固位的下颌种植覆盖义齿经过3年观察,种植体存留率100%,边缘骨吸收<1 mm,种植体周围软组织健康,患者满意度显著提高且维持稳定,义齿无重衬或折断现象,义齿并发症主要是球帽附着体O型圈的置换或固位金属簧的固位力再激活,修理频次0.67次/(年·人)。 结论 在种植体植入位置、方向合适的情况下,球帽附着体固位的下颌双植体覆盖义齿,可获得长期稳定的临床修复效果。     

Immediate loading of implants with fixed restorations in the completely edentulous mandible: report of 27 patients from a private practice.

Numerous authors have documented clinical success in loading threaded implants at the time of implant placement when carefully controlled surgical and restorative protocols are followed. This clinical series documents the application of immediate loading techniques to fixed mandibular restorations in 27 patients who were edentulous or had non-restorable mandibular dentitions. Eighteen patients had complete conventional maxillary dentures, while 9 had natural or fixed prosthetic maxillary dentitions. Twelve different restorative dentists provided prosthetic support for these patients and used 4 different restoration types: laboratory- or office-processed, with cement or screw retention. Five to 8 threaded implants were placed in each patient. One hundred sixty-one of the 186 implants that were placed by the authors were loaded immediately using fixed provisional restorations of the various designs. More than 99% (160/161) of the immediately loaded implants and 99.5% (185/186) of all implants were clinically integrated and radiographically successful at the time of final evaluation for restoration fabrication. After final implant evaluation, no additional implant losses occurred, indicating an implant survival rate of nearly 100% over a mean of 25.0 months (range 13 to 41 months) following implant placement. While a strong preference for cement-retained restorations was apparent, all prostheses showed similar success. The data and the experience described in this report indicate that immediate loading with fixed restorations using appropriate surgical and restorative techniques can be a predictable technique for rehabilitation of the completely edentulous mandible.     

The influence of resilient liner and clip attachments for bar‐implant‐retained mandibular overdentures on opposing maxillary ridge. A 5‐year randomised clinical trial

This study aimed to compare the influence of resilient liner and clip attachments for bar‐implant‐retained mandibular overdentures on opposing maxillary ridge after 5 years of denture wearing. Thirty edentulous male patients (mean age 62·5 years) received two implants in the anterior mandible after being allocated into two equal groups using balanced randomisation. After 3 months, implants were connected with resilient bars. New maxillary complete dentures were then constructed, and mandibular overdentures were retained to the bars with either clips (group I, GI) or silicone resilient liners (group II, GII). The prosthetic and soft tissue complications of the maxillary dentures were recorded 6 months (T_6 m), 1 year (T1), 3 years (T3) and 5 years (T5) after overdenture insertion. Traced rotational tomograms were used for measurements of maxillary alveolar bone loss. The proportional value between bone areas and areas of reference not subject to resorption was expressed as a ratio (R). Change in R immediately before (T0) and after 5 years (T5) of overdenture insertion was calculated. Maxillary denture relining times and frequency of flabby anterior maxillary ridge occurred significantly more often in GI compared with GII. The change of R in anterior part of maxilla was significantly higher than change of R in posterior part in both groups. GI showed significant resorption of anterior residual ridge compared with GII. Relining times and frequencies of flabby ridge were significantly correlated with change in R. Within the limitations of this study, resilient liner attachments for bar‐implant‐retained mandibular overdentures are associated with decreased resorption and flabbiness of maxillary anterior residual ridge and fewer maxillary denture relining times when compared with clip attachments.     

"All-on-4"种植即刻修复治疗的临床回顾性分析

目的 分析施行"All-on-4"种植即刻修复病例的种植体存留率及并发症发生情况,探讨"All-on-4"的技术要点及注意事项.方法 根据纳入及排除标准,纳入2007年1月~2015年12月完成的"All-on-4"种植即刻修复治疗的病例共23例108枚种植体,其中上颌牙列缺失5例,下颌牙列缺失14例,全口牙列缺失4例,均在术后当天或1~2d内取模,并于术后7~10d戴入临时固定修复体,采用螺丝固位,术后3~6个月取模并制作最终修复体,共完成27件临时修复体及27件最终修复体.完成最终修复后平均追踪3年(1~9年),对种植体留存率、修复并发症进行总结及分析.结果 108枚种植体及27件最终修复体至最后1次复查为止,种植体存留率100%.23位患者当中,3位患者发生并发症,并发症发生率13.0%.结论 "All-on-4"在牙列缺失病例治疗中疗效确切可靠,并发症的发生率较低,是一种切实可行的方法.     

Treatment of edentulism using Astra Tech implants and ball abutments to retain mandibular overdentures.

The goal of this study was to provide evidence to support simplified treatment of mandibular edentulism using denture fabrication and implant placement to circumvent the need for second-stage surgeries or prosthodontic superstructures. A 5-year prospective clinical trial is reported, which involved treatment of mandibular edentulism using the single-stage surgical placement of a TiOblast microthreaded titanium screw implant with immediate replacement of a relieved mandibular overdenture and eventual retention of the overdenture with reduced ball abutments. Fifty-eight patients were treated; 116 implants were placed using a single-stage surgical approach, with a duplicate mandibular denture as the tomographic/surgical template. Mandibular dentures were relieved and relined with a tissue conditioning material and placed immediately after implant surgery. After 3 months, Conical Seal Design ball abutments were placed and attachments were secured in the overdentures by heat-polymerizing laboratory reline methods. Five of the 116 consecutively placed implants failed at 2 to 4 months, providing an immediate implant survival rate of 95.69% at the time of attachment connection. Pain and inflammation were not common to all failures, and infection was not reported in any of the 5 failures. The immediate placement of implants by a single-stage surgical procedure in the parasymphyseal region of the mandible, followed by placement of a relined mandibular denture, results in predictable and asymptomatic healing of implants that display the clinical and radiographic features of osseointegration. Encouraging results at the immediate observation period (attachment connection) must be tempered by the need for prudent and detailed clinical and radiologic evaluation over the 5-year trial period.     

Immediate implant placement in edentulous oral cancer patients: a long-term retrospective analysis of 207 patients

Although the functional benefits of implants in the rehabilitation of edentulous cancer patients are well-known, most studies report on postponed implant placement. The outcome of immediate implant placement regarding successful rehabilitation, implant loading and survival is unclear. Two hundred and seven edentulous oral cancer patients that received implants during ablative surgery at the Radboud University Medical Centre between 2000 and 2011 were included. Data regarding the oncological treatment, implant placement, follow-up and prosthodontic rehabilitation were recorded retrospectively with a follow-up period of 5–17 years. Functioning implant-retained dentures were made in 73.9% of the patients. Of the surviving patients, 81.9% had functioning dentures after 2 years and 86.3% after 10 years. Patients with ASA score 1 and younger patients were rehabilitated more frequently. The median time of functioning denture placement was 336 days after surgery, with a negative influence of postoperative radiotherapy. Implant survival was 90.7%, and was lower when the implant was placed in a jaw involved in the tumour. Immediate implant placement during oral cancer surgery led to a high number of edentulous patients rehabilitated with implant-retained dentures, which are placed at an early time.     

An analysis of the implant‐supported overdenture in the edentulous mandible

This investigation examined the cumu‐lative survival rate of the implant‐supported overdenture using two types of attachments in patients treated at Show Chwan Memorial Hospital Implant Center from 1992 to 2006. Fifty‐one patients (30 men and 21 women) were treated with mandibular implant‐supported overdentures. Attachment systems used were the Hader bar with bilateral, cast ERA attachments (Group A, 31 patients with 15 men and 16 women, 134 implants) and the Hader bar with bilateral, distal extension cantilevers (Group B, 20 patients with 15 men and 5 women, 85 implants). Two hundred and four implants remained at the end of the follow‐up period. Among failed implants, 10 implants were in Group A (failure rate: 10/134 = 7·5%), whereas five implants were in Group B (failure rate: 5/85 = 5·9%). Sixty‐six point seven per cent (10/15) of failed implants were placed in the distal anterior mandible, and 33·3% (5/15) were placed in the middle anterior mandible. Survival was also examined with respect to condition of the opposing arch. Patients wearing a maxillary removable partial denture had the highest implant failure rate (5/51 = 9·8%), whereas the failure rate of the maxillary complete denture group was only 5·7%. The most frequent need for maintenance was wear over patrix component of ERA or Hader clip (n = 56). Eight patients experienced connector fracture between ERA and Hader bar, and one experienced distal extension cantilever fracture. The implant‐supported overdenture can be an effective and reliable alternative to the conventional complete mandibular denture. Fewer prosthetic complications were seen in overdentures retained with distal extension cantilever attachments.     

Immediate loading of two implants supporting a ball attachment-retained mandibular overdenture: a prospective clinical study

Background: A prospective clinical study was conducted to evaluate clinically and radiographically the performance of two implants immediately loaded supporting a ball attachment‐retained mandibular overdenture. Materials and Methods: Seventeen completely edentulous patients were included in the study. Each patient received two implants inserted after a minimal flap reflection and no vestibular extension in order to reduce the postoperative swelling and facilitate immediate prosthesis connection. After implant placement, a mandibular complete denture was connected to the implants using ball attachments of appropriate height according to the depth of the peri‐implant tissue. Patients were asked not to remove the denture for 1 week. No limitations to chewing function were given. At implant placement, the maximum value of insertion torque was recorded. Patients were examined at 1, 2, 4, 12, and 52 weeks postsurgery. At postoperative visit, occlusion was checked and the need for any prosthesis maintenance was recorded. The radiographic bone level (RBL) change was measured on periapical radiographs at baseline and 12 months after loading. Results: After 12 months of loading, no implant failure was reported and the survival rate was 100%. Average RBL change was 0.7 mm ± 0.5 mm. Of the 17 cases, two had major prosthetic complications and five patients required minor extra maintenance appointments. Conclusions: The immediate loading of two implants by means of ball attachment‐retained mandibular complete denture may be a predictable treatment option. This clinical approach offers increased stability and comfort, while keeping a high implant success rate.     

Immediate Loading of Two Implants with a Mandibular Implant‐Retained Overdenture: A New Treatment Protocol

Purpose: The aim of this study was to present the clinical outcomes of the immediate loading of two bar‐splinted implants retaining a mandibular overdenture. Materials and Methods: In a clinical trial, 124 edentulous patients were treated according to a new treatment concept, which involves the immediate loading of two bar‐splinted SLActive implants with an implant‐retained mandibular overdenture. The new conventional mandibular denture is used as a template for implant positioning and as an impression tray, and for mounting the retention clip by the dental laboratory. At the same day the implants are placed, the conventional denture is converted into an implant‐retained overdenture. During the healing and evaluation period, resonance frequency analysis (RFA) was undertaken to assess the effect of loading on implant stability and survival. Results: The survival rate of the implants was 98.8% during the evaluation period (12–40 months). Only 3 of the 248 implants were lost. During the healing (osseointegration) phase, the implant‐stability quotient increased significantly (p = .0001). During the evaluation period, four patients (3%) needed a relining of their mandibular overdenture, whereas 13 patients (11%) needed relining of the maxillary denture. Conclusions: Two interconnected implants can be successfully loaded by a mandibular overdenture at the same day of implant placement with a high survival rate of the implants. Only a few patients needed additional relining of the overdenture. Repeated RFA measurements can be useful in gauging implant stability and survival.     

Early functional loading at 5 days for Brånemark implants placed into edentulous mandibles: a prospective,open-ended,longitudinal study

BACKGROUND: Traditionally, implants placed in the mandible heal for 3 to 4 months before they are loaded. In maxillae, healing time usually takes 5 to 6 months. The purpose of this study was to evaluate placement of 4 to 6 implants in edentulous mandibles. The implants were placed between mental foramina for support of non-metal, reinforced, fixed, implant-supported provisional prostheses. A unique method was used to convert existing dentures into fixed, implant-supported appliances. The implants were functionally loaded early (5 days). METHODS: Twenty patients with edentulous mandibles or with 2 to 3 remaining mandibular teeth were enrolled in this open-ended, prospective study. Existing dentures without porcelain teeth were modified for use as a surgical guide. These dentures were used as temporary fixed prostheses. Patients were to have metal-reinforced appliances fabricated by the referring dentists after 3 to 4 months of healing. After implant installation, prosthetic abutments were fixed to the implants and tightened to 20 Ncm without counter torque. Bone quality and quantity as well as implant size and position were entered into a computer database. Impression copings were attached to the abutments, and the modified denture was used for a pick-up impression. After the impression was made, implant replicas were fitted to the impression copings and casts were poured. Gold cylinders were processed into the tissue side of the denture. Laboratory screws were used to attach the denture with gold cylinders to abutment replicas. The dentures were processed, polished, and inserted 5 days after implant surgery. Radiographs were taken to verify proper fit of the gold cylinders to the prosthetic abutments (baseline). Radiographs were taken at each follow-up visit and were used to measure changes in crestal bone levels. RESULTS: Twenty patients received 92 machined-surface commercially pure titanium implants in fully edentulous mandibles. Of the total number of implants placed, two were lost between 0 to 1 year and one between 1 to 2 years. Twenty patients with a total of 90 implants were followed between 0 to 1 year. Fourteen patients have been followed between 1 to 2 years, 7 between 2 to 3 years, and 2 between 3 to 4 years. One patient died after 9 months of loading (4 implants loaded, 2 sleeper implants); another died between 1 to 2 years. A total of 6 implants remained buried (sleepers). At 2 years, the cumulative success rate is 96.3%. Survival of the implant bridges is 100.00%. The mean crestal bone level at 5 days for 11 patients was 2.1 mm (SD 0.526, SE mean 0.159) (measurements were not available for the deceased patient), while the mean level at an average of 15 months was 1.96 mm (SD 0.585, SE mean 0.176). Differences between the measurements taken at 5 days with those taken at an average of 15 months were not significant (P < 0.683). CONCLUSIONS: Results of this study indicate that 4 to 5 implants can be placed and loaded within 5 days of implant insertion with high success (96.3%). Success rates for the interim and final prosthesis are 100%. A simple, possibly cost-effective method of using non-metal reinforced dentures as interim fixed, provisional dentures has been described. Impressions and registrations for making the prosthesis can be made at the time of implant installation, and this method is accurate enough to make provisional restorations. The modified denture can function as an interim fixed, implant-supported prosthesis for up to 30 months. Results of x-ray measurements indicate stable crestal bone levels for up to an average of 15 months.     

Does a prosthodontist spend more time providing mandibular two-implant overdentures than conventional dentures?

PURPOSE: In this article, the time taken by a prosthodontist to fabricate and maintain mandibular overdentures retained by two implants and conventional dentures is compared. MATERIALS AND METHODS: Sixty edentulous patients between the ages of 65 and 75 completed a randomized clinical trial. All received new maxillary conventional dentures and either a mandibular conventional denture (n = 30) or a two-implant overdenture on ball attachments (n = 30). The time spent by the prosthodontist and the number of visits required for treatment, including both scheduled and unscheduled visits, were recorded for each patient from preliminary impressions to 6 months following delivery. Data from the two groups were compared using Mann-Whitney U tests. RESULTS: The prosthodontist spent a mean total time of 296 minutes in treating an implant overdenture patient and 282 minutes on a conventional denture patient during the period from preliminary impressions to the 6-month follow-up. The mean numbers of appointments were 10.1 (implant group) and 10.8 (conventional group). These differences were not significant. CONCLUSION: Although additional knowledge is required to treat patients with implant prostheses, the time required by the prosthodontist to provide two-implant mandibular overdentures with ball attachments was not significantly different than the time needed for conventional denture treatment.     

Prosthodontic complications in a prospective clinical trial of single-stage implants at 36 months

PURPOSE: The present material reports on prosthodontic complications in a trial of 51 patients with prostheses supported by single-stage implants over a period of 36 months. MATERIALS AND METHODS: One hundred eighty-six single-stage implants were placed in 51 patients over a 3-year period in 2 carefully controlled prospective clinical trials. Nineteen of the patients (103 implants) were completely edentulous and restored with a maxillary complete denture and a mandibular fixed-detachable complete prosthesis. Single metal-ceramic crowns or fixed partial dentures were fabricated for the remaining 32 patients (83 implants). The fixed restorations were either screw-retained or cemented. RESULTS: All patients/implants were followed for a minimum of 3 years. Complications in the edentulous patients included fracture of denture teeth, fracture of the maxillary denture, and occlusal screw loosening. Occlusal screw loosening and loss of the resin composite access plug were the only complications observed in the patients treated with screw-retained restorations. No complications were found in the patients restored with cemented restorations on solid abutments. DISCUSSION: Problems with prostheses were very common in the completely edentulous patients (13 of 19 patients encountered complications), possibly a result of increased bite force or inadequate laboratory technique. Tooth fractures were seen more frequently in men than in women. Complications occurred in only 5 of the 32 partially edentulous patients. CONCLUSION: Complications were associated with laboratory-related procedures rather than the implant system itself.     

Effect of postoperative radiotherapy on the functional result of implants placed during ablative surgery for oral cancer

The purpose of this retrospective study was to evaluate the survival of dental implants placed during ablative surgery in the interforaminal region of the original edentulous mandible in patients with squamous cell carcinoma of the oral cavity in relation to postoperative radiotherapy. Forty-eight patients treated in 1996–2003 with surgery alone or in combination with postoperative radiotherapy were analysed. In all patients, 2 to 4 Brånemark Mk II/III 2-phase implants were placed during tumour resection. A total of 139 implants were placed of which 61 (21 patients) received postoperative radiotherapy: 60–68 Gy as a boost dose on the primary tumour site and 10–68 Gy on the symphyseal area. No difference was found in percentage of functional dentures on implants between the radiated and non-radiated groups. The success rate of osseointegration was 97% in the postoperative irradiated group and 100% in the non-irradiated group. The prosthetic success rate (75%) was lower because in 12 of the 48 patients (34 implants) a functional denture could not be fitted due to tumour recurrence or metastasis (7 patients, 22 implants) or for psychological reasons (4 patients, 12 implants), independent of whether radiotherapy was administered. Postoperative radiotherapy does not affect the osseointegration of dental implants placed during tumour ablation and the ultimate number of functional dentures. Primary implant placement in edentulous mandibles may have advantages over secondary implant placement in patients with oral squamous cell carcinoma.     

The management of a completely edentulous patient using simultaneous maxillary and mandibular CAD/CAM-guided immediately loaded definitive implant-supported prostheses: a clinical report

Functional rehabilitation of a completely edentulous patient with removable prostheses is a clinical challenge. A patient with an edentulous maxilla and mandible received 6 endosseous implants in the maxilla and 5 implants in the mandible using CAD/CAM surgical templates. Definitive maxillary and mandibular implant-supported fixed complete dentures were connected immediately after implant placement using a CAD/CAM-guided implant surgical placement protocol.     

Clinical evaluation of overdenture restorations supported by osseointegrated titanium implants: a retrospective study

This paper reports the results of using osseointegrated titanium implants as abutments for overdenture restorations in the mandibles of 62 edentulous patients. All of these patients were edentulous for several years and required complete dentures. Six months after prosthodontic treatment, two implants (ITI, Straumann) were placed with consideration of the denture base and morphologic aspects of the mandibular residual ridge. The retention devices consisted of a bar connector or single ball-shaped precision attachments. Three or four implants splinted with a bar were placed in a control group of 11 patients. Attached keratinized gingiva (greater than or equal to 2 mm) surrounded approximately 48% of the buccal and 55% of the lingual implant sites. Evaluation after periods of 6 to 66 months postoperatively revealed good clinical results with five patients lost to recall in 1989. Two implants were lost after overdenture insertion. The findings suggest that two implants may adequately serve as retention for a mandibular complete denture and that attached gingiva surrounding the implants does not seem to be prerequisite for healthy function.     

Long-term effects on chewing with mandibular fixed prostheses on osseointegrated implants

Twenty-seven edentulous patients with denture adaptation problems were first given optimal conventional complete dentures and then a fixed prosthesis on osseointegrated dental implants in the lower jaw (and a complete maxillary denture). Masticatory function was evaluated by means of a questionnaire, a comminution test for chewing efficiency, and bite force measurements on four occasions: with the original (I) and optimal complete dentures (II) and 2 months (III) and 3 years (IV) after insertion of the fixed mandibular prosthesis on implants. No significant improvement of masticatory function was found after conventional denture treatment. After insertion of the fixed mandibular implant bridge, a marked improvement of the patients' assessment of their chewing ability and of the results of the chewing efficiency test and the bite force measurements was recorded. The test results were further improved after the 3-year observation period, which indicates that adaptation to the new prosthetic situation is a gradual process.     

Immediate loading of mandibular overdentures supported by unsplinted direct laser metal-forming implants: results from a 1-year prospective study

Background: At present, only some studies have dealt with immediate loading of unsplinted implants supporting mandibular overdentures. The aim of this prospective study is to evaluate treatment outcomes of mandibular overdentures supported by four one‐piece, unsplinted, immediately loaded, direct laser metal‐forming (DLMF) implants by assessing implant survival rate, implant success, marginal bone loss, and prosthetic complications. Methods: A total of 96 one‐piece DLMF implants were inserted in the edentulous mandible of 24 patients. Four implants were placed in each edentulous mandible. Immediately after implant placement, a mandibular overdenture was connected to the implants. At 1‐year follow‐up, clinical, radiographic, and prosthetic parameters were assessed. Success criteria included absence of pain, suppuration, and implant mobility; absence of continuous peri‐implant radiolucency; and distance between the implant shoulder and the first visible bone contact <1.5 mm. Results: After a 1‐year loading time, the overall implant survival rate was 98.9%, with only one implant lost. Among the surviving 95 implants, two did not fulfill the success criteria; therefore, the implant success rate was 97.8%. The mean distance between the implant shoulder and the first visible bone contact was 0.28 ± 0.30 mm (95% confidence interval, 0.24 to 0.32). Some prosthetic complications were reported. Conclusion: Based on the present results and within the limits of this study, the immediate loading of four unsplinted DLMF implants by means of ball attachment–supported mandibular overdentures seems to represent a safe and successful procedure.     

Mandibular implant-supported removable partial denture with distal extension: a systematic review

Summary The aim of this article is to investigate patient satisfaction, survival rate of implants, and prosthetic complications or maintenance for rehabilitation with removable partial dentures associated with implants in mandibular Kennedy class I and II cases. A systematic literature review was conducted by three independent reviewers including articles published from January 1981 through September 2011. Medline and Cochrane Library electronic databases were used in addition to hand searching to assess clinical outcomes for mandibular implant-supported removable partial denture with distal extension. This review yielded 1751 records that were narrowed down to 5. The studies revealed implant survival rates ranging from 95% to 100% with one failure reported of 98 implants. The removable partial dentures associated with implant in mandibular free-end arches showed some complications and need of repair for relining, pitting of the healing abutment, replacement of resilient component of the attachment, damage in framework, screw loosening and damage in acrylic denture base. Patient satisfaction was evaluated through a five-point questionnaire, and results ranged between 4·12 and 5·0, considering 1 as the least favourable situation. The literature review showed increase in patient satisfaction and high survival rates of implants associated with mandibular removable partial dentures with distal extensions. However, some complications and need of prosthetic repair were reported. Although this treatment approach could represent a low-cost and beneficial rehabilitation for free-end mandibular ridges, the lack of controlled and randomised well-designed clinical trials suggests further studies with more representative samples to validate the outcomes of this treatment modality.     

A 48-month multicentric clinical investigation: implant design and survival

This report is based on a total of 2,955 implants of 6 different designs, randomized and placed in 829 patients and followed for 48 months. Implant failure was defined as nonintegration at uncovering or removal due to mobility, persistent pain, infection, and evidence of radiographic bone loss. Failures were reported for 3 phases of treatment: implant placement to uncovering (phase 1), uncovering to loading (phase 2), and postloading (phase 3). Differences in survival were compared with Kaplan-Meier survival curves. The maxillary single tooth application resulted in 95.2% survival for the hydroxyapatite-coated grooved implants. In the maxillary completely edentulous application, survival of hydroxyapatite grooved and screw implants were considerably better compared with the titanium screw implants. The hydroxyapatite-coated cylinder had better survival than the titanium basket and screw designs in the mandibular completely edentulous application. The hydroxyapatite-coated cylinder and grooved implants in the maxillary posterior partially edentulous application had similar survival rates. The survival of the hydroxyapatite-coated cylinder exceeded that of the titanium basket in mandibular posterior partially edentulous applications. Analyses by phase of treatment indicated a pattern of early failure for nonhydroxyapatite-coated implants compared with hydroxyapatite-coated implants. The implant with the highest survival at all phases of treatment was the hydroxyapatite-coated press-fit cylinder. Two hydroxyapatite-coated implant designs performed well in the challenging posterior maxillary region.