Private practice results of screw-type tapered implants: survival and evaluation of risk factors

PURPOSE: The aims of this study were to examine the long-term survival and the prosthetic treatment outcome of screw-type, tapered implants placed in a private practice setting and to explore potential risk factors of implant failures. MATERIALS AND METHODS: In this retrospective analysis of patients treated with endosseous screw-type tapered implants, data relative to implant placement and failure, implant length, location, prosthetic treatment, medical history, smoking habits, and oral health behavior were gathered by chart review and questionnaire. An oral examination was also conducted. Cumulative survival rates were estimated through Kaplan-Meier methods. Comparisons between subgroups of patients were made using the log-rank statistical test. The association between several factors and implant failures was analyzed using Cox regression analyses (random and dependent models). Differences were considered significant when P < .05. RESULTS: The survival rate of 663 implants placed in 159 patients (65 men, 94 women; 80.7% of 197 eligible patients) was 91.8% after 120 months. Mandibular implants had a higher survival rate than maxillary implants (96% versus 89%, P = .011). The failure rates for implants were 15.0% among current smokers, 9.6% among former smokers, and 3.6% among nonsmokers. The differences between nonsmokers, former smokers, and current smokers were significant (nonsmokers versus former smokers: P = .036, nonsmokers versus current smokers: P < .001, former smokers versus current smokers: P = .003). Only number of years of smoking was significantly associated with an increased risk of implant failures (P = .036 using dependent estimation; P = .004 using independent estimation). The HR increased to 6.6 for patients who had smoked for 45 years. Loosening of prosthetic components were rare (n=12). No fractures of screws or implants were found. DISCUSSION: Higher failure rates for former smokers and a dose-response effect between duration of smoking and implant failure rates suggested that permanent tissue damage from smoking may occur in addition to immediate local and systemic effects. The frequency of prosthetic complications was comparable to other studies. CONCLUSIONS: Screw-type tapered implants placed in a private dental office demonstrated a cumulative survival rate of 91.8%. The relative risk of implant failure increased with the duration of smoking.     

Retrospective clinical evaluation of tapered screw-vent implants: results after up to eight years of clinical function

Uncertainty about the causes of peri-implant bone loss and difficulties in measuring it often have resulted in omission of bone loss data from published long-term implant studies. This nonrandomized, uncontrolled, retrospective study evaluated the clinical outcomes of treatment with tapered, multithreaded implants with a special emphasis on peri-implant crestal bone status. Chart reviews were conducted of 60 patients who had been treated with 267 implants for the placement of 1 or more missing and/or unsalvageable teeth, and who met general inclusion criteria for dental implant therapy. In all cases, marginal bone changes were calculated from the cementoenamel junction (CEJ) or the implant neck to the crestal bone level with standardized radiographs taken at implant placement (baseline) and during annual follow-up. After a mean followup of 7.5 years, implant survival was 98.5% (263/267) for all implants placed, and implant success was 96.2% (253/263) for all surviving implants. No discernible bone loss was evident in 88% of surviving implants. Crestal bone loss was observed in 25% (15/60) of total study subjects and in 12% (32/263) of all surviving implants: 29 implants exhibited 1 mm of bone loss and 3 implants lost 2 mm of bone. Low-density maxillary jawbone and more extensive bone remodeling, which were required around implants immediately placed into extraction sockets, were the probable causes of observed bone loss in this study. Implants exhibited excellent long-term outcomes with little or no bone loss.     

Prospective clinical evaluation of 835 multithreaded tapered screw-vent implants: results after two years of functional loading

Multithreaded tapered screw implants have been used for several years, but lack of clinical documentation about marginal bone stability and survival rates have raised concerns about the design among some clinicians. This study prospectively evaluated the survival rates, success rates, and marginal bone stability of multithreaded tapered screw implants. A total of 835 implants in diameters of 3.7 mm (9%), 4.7 mm (76%), and 6.0 mm (15%) were placed in 328 patients using a single-stage, delayed-loading protocol. The implants were restored with a variety of prostheses and monitored over 2 years of functional loading. Five implants failed and were removed before loading. Cumulative implant survival was 99.4% (n = 835); differences between mandibular (99.0%, n = 408) and maxillary (99.8%, n = 427) implants were not statistically significant (P > .20). Mean marginal bone resorption was 1.66 mm (+/- 0.13 mm). Six implants failed to meet the success criteria by sustaining mesial and distal bone loss below the first implant thread; however, they remained stable and continued functioning without pain or inflammation. Cumulative implant success was 98.6% (n = 835); differences between maxillary (98.6%) and mandibular (98.8%) implants were not statistically significant (P > .20). Success rates by implant diameter were 98.6% (3.7 mm), 98.4% (4.7 mm), and 100% (6 mm). After 2 years of functional loading, survival and success rates for multithreaded tapered implants placed in a nonsubmerged protocol equaled or surpassed those of single-thread, straight-walled implant historical controls.     

Long-term evaluation of hollow screw and hollow cylinder dental implants: clinical and radiographic results after 10 years

BACKGROUND: In 1988, an implant manufacturer offered a new dental implant system, with a wide choice of hollow cylinder (HC) and hollow screw (HS) implants. The purpose of this retrospective study of HS and HC implants was to evaluate clinical and radiographic parameters of peri-implant tissue and to analyze surgical and prosthetic aftercare. METHODS: A total of 89 HS and 26 HC implants in 38 edentulous patients were available for complete evaluation. The patients were treated with overdentures stabilized by two or four implants. The follow-up period was 10 years. RESULTS: The results of the clinical evaluation showed a mean sulcus probing depth of 3.3+/-1.3 mm (range=2 to 10 mm). The mean radiographic bone loss was 2.2+/-2.1 mm (range=0.1 to 12.2 mm). One implant (HS) was removed during the osseointegration period. Three other implants (two HS and one HC) in three patients had to be removed after 10 years. The survival rate of the HS implant (96.6%) was comparable to the HC implant (96.1%). The success rate of the HS implant (93.3%) was slightly more favorable compared to the HC implant (88.5%). The HS and HC implants met the Albrektsson criteria of success. CONCLUSIONS: HS and HC implants provide a stable base for long-term support of a mandibular overdenture. Furthermore, it is important to monitor peri-implant bone level by taking annual radiographs and measuring probing depth, especially after prolonged service.     

Long-term evaluation of non-submerged hollow cylinder implants. Clinical and radiographic results

From 1974 various types of hollow cylinder ITI-implants were placed before the new generation of Bonefit ITI-implants was developed in the mid-eighties. The aim of this study was the clinical and radiographic evaluation of hollow cylinder implants that were inserted during the time period of 1978-1987 in partially and completely edentulous patients to support overdentures, fixed partial prostheses and single crowns. Altogether, 71 patients with a total of 132 hollow cylinder ITI-implants still in situ had been followed regularly during the entire observation period of 11.4 to 19.7 years (mean 14.1). Thirteen implants had to be removed before an observation period of 10 years was completed, 4 additional implants were lost after being in function for over 10 years and two further implants were considered to be failures at the time of the examination. Thus 91.4% of the implants were still in situ after 10 years and the survival rate for a mean observation period of 14.1 years was 84.6%. Periimplant parameters were used to assess the clinical conditions of the implants. On the radiographs, horizontal bone loss or angular defects could be detected on 40% of all implants if compared to the base-line situation. The probing depths around these implants were significantly increased compared to implants with an unchanged bone level, however the mean probing depths did not exceed 3.5 mm and 2.8 mm respectively. From this clinical evaluation one may conclude that with the early generation of hollow cylinder ITI-implants favorable long-term results were achieved.     

即刻负重带内孔种植体的长期效果

目的：对应用即刻负重Straumann种植体支持杆固位覆盖义齿的患者，进行长期效果回顾性评估。材料和方法：所有病例均为自1981～1991年期间在巴塞尔大学口腔外科、口腔放射科和口腔内科学院进行外科手术和修复治疗的患者。每例患者均于手术当时安装连接杆带入义齿即刻负重。对能随访到的患者进行临床复诊检查，并对结果进行统计学分析。结果：44例患者植入176颗带内孔Straumann种植体的患者中（每个患者4颗），其中随访到23例患者共89颗种植体。种植体的平均观察时间为122年（8～18年）。3例种植体脱落。5例种植体不符合预定的成功标准。根据Cutler和Ederer的定义．成功概率为83．3％。结论：结果表明，即刻负重带内孔Straumann种植体不一定需骨结合所要求的4个月治疗期。     

Long-term results of immediately loaded interforaminal implants.

OBJECTIVE: To collect, retrospectively, long-term results from patients who received immediately loaded Straumann implants with bar-retained overdentures. METHOD AND MATERIALS: The surgical and prosthetic treatment took place between 1981 and 1991 at the Department of Oral Surgery, Oral Radiology, and Oral Medicine, University of Basel. In each case on the day of the operation, the patients were fitted with a bar that was immediately loaded with a hybrid prosthesis. Patients who were available at the time of this study were clinically reexamined and statistically assessed. RESULTS: Among the 44 patients who received 176 interforaminal Straumann implants (4 implants per patient), follow-up was possible in 23 patients, who had received a total of 89 implants. The mean observation time for the implants was 12.2 years (8 to 18 years). Three implants were lost. Five implants did not meet the predetermined success criteria. Using the definition by Cutler and Ederer, the probability of success was 83.3%. CONCLUSIONS: The results show that the requisite 4-month healing time for immediately loaded interforaminal Straumann implants with bars does not have to be observed.     

5-year clinical experience with BTI dental implants: risk factors for implant failure

Objectives: The aims of this study were to identify with appropriate statistical tests the risk factors associated with implant failure and to evaluate the long-term survival of dental implants using implant loss as an outcome variable and performing an implant-, surgery- and patient-based analysis of failures.
Material and Methods: A retrospective cohort study design was used. One thousand sixty patients received 5787 BTI^® implants during the years of 2001–2005 in Vitoria, Spain. The potential influence of demographic items, clinical items, surgery-dependent items and prosthetic variables on implant survival was studied. Implant survival was analysed using a life-table analysis. Cox proportional hazards regression was used to identify risk factors related to implant failure.
Results: Smoking habits, implant position, implant staging (two-stage implants) and the implementation of special techniques were statistically correlated with lower implant survival rates. Two risk factors associated with implant failure were detected in this study: implant staging (two-stage implants) and the use of special techniques. Additionally, the overall survival rates of BTI^® implants were 99.2%, 96.4% and 96% for the implant-, surgery- and patient-based analysis, respectively. Totally, 28 out from 5787 implants (0.48%) were lost during the observation period. Most of the patients with implant failure (69.6%) presented chronic or aggressive periodontitis.
Conclusions: Implant staging and the use of special techniques are risk factors for implant failure.     

A prospective multicenter evaluation of immediately functionalized tapered conical connection implants for single restorations in maxillary anterior and premolar sites: 3-year results

Objectives

This multicenter prospective clinical trial investigated immediately provisionalized, anodized, conical connection, tapered implants with platform shifting in maxillary anterior and premolar sites.

Materials and methods

Patients requiring single-tooth implant-supported restorations in maxillary anterior and premolar sites were enrolled. Implants were immediately provisionalized and evaluated at insertion, 6 months, and annually thereafter. Outcome measures were marginal bone level change (ΔMBL), cumulative survival rate (CSR), and success rate, soft-tissue parameters, and oral health impact profile (OHIP). ΔMBL and Pink Esthetic Score were analyzed using Wilcoxon signed-rank tests. CSR was calculated using life table analysis. Other soft-tissue parameters were analyzed using sign tests.

Results

Of 94 enrolled patients (99 implants), 84 (88 implants) attended the 3-year follow-up. After an initial bone loss between implant insertion and 6 months (− 0.92 ± 1.23 mm), bone levels stabilized from 6 months to 3 years (0.13 ± 0.94 mm) with no significant change. The 3-year CSR was 98.9%, and the cumulative success rate was 96.9%. Papilla index scores of 2 or 3 were observed at 88.6% of sites at the 3-year visit compared with 32.8% at implant insertion. Improvements were observed for all other outcomes, including bleeding on probing, esthetics, plaque, and OHIP.

Conclusions

This restorative protocol was associated with high primary stability, patient satisfaction, stable bone levels, and an overall improvement of the soft tissue outcomes over a 3-year period.

Clinical relevance

The presented treatment is a viable option for single-tooth restorations of maxillary anterior teeth and premolars with successful short- to mid-long-term clinical outcomes.

     

Shorter implants in clinical practice: rationale and treatment results

INTRODUCTION: The use of shorter implants offers a number of potential advantages if such utilization yields the same level of treatment success as the use of longer implants. The purpose of this retrospective study was to assess the survival of short implants in various clinical situations in function over time. MATERIALS AND METHODS: A retrospective study was conducted of all patients treated between May 2000 and May 2007 who received endosseous implants that were less than 10 mm in length. Patient age, gender, location of implants, type of prosthesis, time in function, and stability of peri-implant crestal bone were assessed. RESULTS: The retrospective analysis identified 2,073 implants of 6 mm, 7 mm, 8 mm, or 9 mm in length placed in a variety of clinical situations in 1,774 patients. Cumulative implant survival rates for implants in function in various areas of the mouth supporting single crowns or short-span fixed prostheses ranged from 98.1% to 99.7%. Each indication was examined with regard to individual success and failure rates and mean time in function. CONCLUSIONS: When utilized appropriately, implants of 6 to 9 mm in length demonstrate cumulative survival rates under function comparable to those reported for longer implants.     

Long-term performance of Osseotite implants: a 6-year clinical follow-up

In this prospective, multicenter study, 147 Osseotite implants were placed in 75 patients (32 men and 43 women with a mean age of 54 years) using a conventional two-stage surgical protocol with 3 months of healing time in the mandible and 6 months in the maxilla. Of the 147 implants, 69% were inserted in posterior sites and 64% were short implants of 10 mm or less. From the time of implant insertion to second-stage surgery, 5.1 months (+/- 2.4 months) elapsed. Restorative treatments included 25 single-tooth replacements (28.4%), 58 short span fixed bridges (65.9%), 1 full-arch reconstruction (1.1%), and 4 overdentures (4.5%). The mean time from implant placement to final recall was 74.1 months (+/- 8.9 months). At second-stage surgery and at 6-month and annual follow-up examinations, implants were evaluated for mobility, peri-implant radiolucency, gingival health, signs and symptoms of infection, neuropathies, paresthesia, and crestal bone levels. A 3-year interim report identified 5 implant failures, 4 of which occurred as a clustering phenomenon in a single, medically compromised patient. Using the life table analysis method, the cumulative implant success rate was calculated at 96.6%. The 3-year interim report indicates that the implants developed an extended, functional osseous state that remained stable for more than 6 years.     

Long-term evaluation of osseointegrated implants in regenerated and nonregenerated bone

This investigation evaluated the predictability of dental implants subjected to bone regeneration procedures at the time of insertion. Fifty-two test implants were inserted into sites with periimplant bone defects. A calcium carbonate allograft material with or without a fibrin-fibronectin sealing system was used to fill the defects. Sixty control implants were inserted into an adequate volume of nonaugmented bone. Each of the 29 study patients received at least one test implant and one control implant. At the second-stage surgery, fill of the bone defect was assessed as complete or incomplete. The cumulative success rate was 91.7% (mean follow-up 55 mo) for the test implants and 93.2% (mean follow-up 59 mo) for the control implants. Within the test group, implants with complete bone fill achieved 97.6% success versus 59.1% success for implants with incomplete bone fill. These preliminary results suggest that implants placed with simultaneous bone regeneration procedures achieve long-term predictability that is comparable to that of implants placed in an adequate volume of bone, provided that complete bone fill of the periimplant defect is achieved. Long-term studies with other augmentation materials are needed to fully validate these findings.     

Long-term results after placement of dental implants: longitudinal study of 1,964 implants over 16 years.

In a retrospective study, Kaplan-Meier implant survival analyses were conducted on 883 patients with 1,964 implants of various systems placed, followed up, documented, and statistically evaluated at an oral surgery and dentistry practice between January 1981 and January 1997. The goal of this study was to evaluate the success of osseointegrated implants of the Br?nemark, Frialit-1 (Tübinger Implant), Frialit-2, and IMZ systems and Linkow blade implants. For all systems, mandibular implants were generally more successful than maxillary implants. The preprosthetic loss rate was 1.9%, and 4.3% of implants were lost after prosthetic treatment. The lowest loss rates were seen with implants in intermediate and distal extension spaces and with single-tooth replacements using IMZ, Frialit-2, and Br?nemark implants. In edentulous arches, implants of the IMZ and Br?nemark systems had the lowest failure rates.     

Prospective clinical evaluation of 1920 Morse taper connection implants: results after 4 years of functional loading

Purpose: This study evaluated the survival rate and the clinical, radiographic and prosthetic success of 1920 Morse taper connection implants.
Material and methods: One thousand nine hundred and twenty Morse taper connection implants were inserted in 689 consecutive patients, from January 2003 until December 2006. Implants were clinically and radiographically evaluated at 12, 24, 36 and 48 months after insertion (mean follow-up per implant: 25.42 months). Modified plaque index (mPI), modified sulcus bleeding index, probing depth (PD) and the distance between implant shoulder and first crestal bone–implant contact (DIB) were measured in mm. Success criteria included the absence of suppuration and clinically detectable implant mobility, PD<5 mm, DIB<1.5 mm after 12 months of functional loading and not exceeding 0.2 mm for each following year, the absence of recurrent prosthetic complications at the implant–abutment interface. Prosthetic restorations were fixed partial prostheses (364 units), single crowns (SCs: 307 units), fixed full-arch prostheses (53 units) and overdentures (67 units).
Results: The overall cumulative implant survival rate was 97.56% (96.12% in the maxilla and 98.91% in the mandible). The cumulative implant success rate was 96.61% (95.25% in the maxilla and 98.64% in the mandible). Only a few prosthetic complications were reported (0.65% of loosening at implant–abutment interface in SCs).
Conclusion: The use of Morse taper connection implants represents a successful procedure for the rehabilitation of partially and completely edentulous arches. The absence of an implant–abutment interface (microgap) is associated with minimal crestal bone loss. The high mechanical stability significantly reduces prosthetic complications.     

Long-term results of subperiosteal implants combined with cancellous bone grafts

Twenty-three subperiosteal implants combined with cancellous bone grafts were done at the University of Washington over a four-year period. A modification of the original technique as used with 19 of the patients is described, as well as the follow-up evaluation. The greatest problem occurred at the mucosal-metal junction, resulting in multiple infections and some failures. This technique appears to be comparable with the simple subperiosteal implant but not significantly better.     

A prospective clinical study of non-submerged immediate implants: clinical outcomes and esthetic results

OBJECTIVES: To evaluate healing of marginal defects in immediate transmucosal implants grafted with anorganic bovine bone, and to assess mucosal and radiographic outcomes 3-4 years following restoration. MATERIAL AND METHODS: Thirty immediate transmucosal implants in maxillary anterior extraction sites of 30 patients randomly received BioOss (N=10; BG), BioOss and resorbable collagen membrane (N=10; BG+M) or no graft (N=10; control). RESULTS: Vertical defect height (VDH) reductions of 81.2+/-5%, 70.5+/-17.4% and 68.2+/-16.6%, and horizontal defect depth (HDD) reductions of 71.7+/-34.3%, 81.7+/-33.7% and 55+/-28.4% were observed for BG, BG+M and control groups, respectively, with no significant inter-group differences. Horizontal resorption was significantly greater in control group (48.3+/-9.5%) when compared with BG (15.8+/-16.9%) and BG+M (20+/-21.9%) groups (P=0.000). Ten sites (33.3%) exhibited recession of the mucosa after 6 months; eight (26.7%) had an unsatisfactory esthetic result post-restoration due to recession. Mucosal recession was significantly associated (P=0.032) with buccally positioned implants (HDD 1.1+/-0.3 mm) when compared with lingually positioned implants (HDD 2.3+/-0.6 mm). In 19 patients followed for a mean of 4.0+/-0.7 years, marginal mucosa and bone levels remained stable following restoration. CONCLUSION: BioOss significantly reduced horizontal resorption of buccal bone. There is a risk of mucosal recession and adverse soft tissue esthetics with immediate implant placement. However, this risk may be reduced by avoiding a buccal position of the implant in the extraction socket.     

Private practice results of dental implants. Part I: survival and evaluation of risk factors--Part II: surgical and prosthetic complications

The aim of this study is to present the clinical data from the use of implants that were placed and restored in four independent private dental offices. In part I, the survival rate was calculated and the failure causes were associated with some potential risk factors. In part II, the surgical and prosthetic complications were also recorded and associated both with failures and clinical factors. During 1990-2002 (mean observation 4.6 years), 1692 dental implants were placed and restored in 405 patients in 4 private clinics following the same treatment protocol. The prosthetic restorations included fixed partial dentures, single crowns, and overdentures. The results were statistically analyzed and survival rate probability curves were calculated according to Kaplan-Meier analysis. Part I: Seventy-four implants (4.4%) in a total of 1692 implants failed. The mean of time elapsed before removal of the failed implants was 40 months. The failure rate was higher in the maxilla in patients with metabolic diseases, in D4 bone quality, in smokers, and in patients with insufficient oral hygiene. Part II: Surgical complications happened to 65 implants (3.8%). Prosthetic complications appeared in 152 implants (9%). The overall survival rate (95.6%) in a period of 1 to 12 years is comparable to other studies. The early failures represented a high percentage of failures. Peri-implantitis was the main cause of late failures. The results of this study indicate that the use of implants in private clinics is a safe and predictable method for the treatment of partially or completely edentulous patients, if the proper clinical protocol is followed. The need of a severe recall program must also be emphasized.