Implant prosthodontic rehabilitation of fibula free-flap reconstructed mandibles: a Memorial Sloan-Kettering Cancer Center review of prognostic factors and implant outcomes

PURPOSE: This study aimed to estimate the cumulative survival rates (CSRs) of implants placed in reconstructed mandibles and to identify prognostic factors that may influence implant survival. MATERIALS AND METHODS: The charts of 24 patients (10 male, 14 female) who had undergone mandibular resection and reconstruction with fibula free-flaps treated with implant-supported prostheses from April 1986 through December 2001 were reviewed. Information on demographics, surgical characteristics, treatment modalities, dentition, implant parameters, prostheses, and hyperbaric oxygen therapy (HBO) was gathered. Kaplan-Meier survival estimates were generated for the 100 implants that satisfied the inclusion criteria. Multivariate Cox proportional hazards regression models accounting for correlated implants within subjects were developed to identify prognostic factors for implant survival. RESULTS: Ninteen implants had been placed in native mandible (3 in irradiated bone) and 81 in fibula bone flap. Six implants failed during the follow-up period (mean 51.7 months). The overall 5- and 10-year CSRs were 97.0% and 79.9%, respectively. In the univariate analysis, variables associated with implant survival were age, gender, chemotherapy, radiation therapy, HBO, irradiated bone, implant diameter, xerostomia, trismus, opposing dentition, and type of prosthesis. At 5 years, the CSR of implants in patients with HBO was 86.7%; HBO was statistically associated with an increased risk for implant failure (P = .005, hazard ratio = 19.79, 95% CI: 2.42 to 161.71). DISCUSSION: The CSR was lower when implants were placed in a previously irradiated mandible. There is still a lack of reliable clinical evidence to support the effectiveness of HBO in these patients. CONCLUSIONS: A high survival rate was demonstrated for implants placed in fibula free-flap reconstructed mandibles. The finding that HBO was a risk factor can probably be attributed to the small sample size; further study is needed in this patient population.     

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.     

Technical and biological complications/failures with single crowns and fixed partial dentures on implants: a 10-year prospective cohort study

OBJECTIVES: To assess prospectively over 10 years the incidences of technical and/or biological complications and failures occurring in a cohort of consecutive partially edentulous patients with fixed reconstructions on implants of the ITI Dental Implant System. METHODS: Eighty-nine patients were available, 34 (38.2%) were male, 55 (61.8%) were female. At the 10-year examination (range 8-12 years), they were 58.9 years old (range 28-88 years). RESULTS: Single crowns (SC): 48 patients had been restored with 69 SC on 69 implants. Five of the implants with the crowns were lost because of biological failures. Two crowns (2.9%) were remade because of technical failures. Total failure amounted to seven (10%). Implant borne fixed partial dentures (I-I FPD): In 29 patients who had been restored with 33 implant borne suprastructures, the total number of failed I-I FPD was 2 (6.1%). Tooth-implant borne fixed partial dentures (I-T FPD): In 21 patients, 22 mixed tooth-implant borne reconstructions were constructed. The number of failed FPD reached 7 (31.8%). Statistically significantly fewer biological failures occurred with I-I FPD compared with the I-T FPDs (ANOVA, Bonferroni, P=0.022). The I-T FPDs experienced statistically significantly more frequent technical failures compared with the other two groups of suprastructures (P=0.003, 0.031). Consequences of complications: The occurrence of loss of retention as a complication increased the odds ratio (OR) to 17.6 (P<0.001) to end up in a technical failure. Similarly, the event of a porcelain fracture increased the OR for the suprastructure to be a failure at 10 years to 11.0 (P< or =0.004). Treatment of periimplantitis increased the OR to 5.44 (P< or =0.011) to result in a biological failure compared with implants in which this type of treatment was not applied. CONCLUSION: The three groups of suprastructures demonstrated marked differences in their patterns of failures and complications. Complications increased the risk for failure. Support by CRF, University of Berne, Switzerland.     

Time dependent failure rate and marginal bone loss of implant supported prostheses: a 15-year follow-up study

This study deals with 4971 implants (Brånemark system) installed in 1315 patients, either fully or partially edentulous, and followed from implant installation up to the last control. A predominance of female patients (61%) and a nearly equal number of upper and lower jaws characterised the study group. Patients were scheduled each 6–12 months for recall. The observation time varied from 0.5 to 15 years (mean 5.1). The whole cohort was split up into compromised (n=59) and non-compromised (n=1256) patients. The former are defined as grafted (autologous bone) and patients irradiated in the head and neck area. In the compromised patients 24 out of 59 patients (40.6%) showed failures, in whom 59 out of 310 (19%) implants failed. In the non-compromised patients, implant failures were observed in 11.6% of the patients, which corresponds to 5.9% of the installed implants, excluding iatrogenic failures. Failures were further divided chronologically into early (up to 1 year after abutment connection) and late failures. There were early implant failures in 12.5% of the compromised patients and in 3.4% of the others. Late implant failures occurred in 7.4 and 2% of the two patients groups, respectively. While gender did not affect the failure rate, implant lengths, corresponding to the available bone height did, since a 21.5% failure rate for the 7-mm implants contrasts with 4.1 and 3.8% for 13- and 15-mm implants, respectively. Early as well as annual late failures are more frequently found in the maxilla. Implant fractures only occurred in the fixed (both partial and full) prosthesis group but never surpassed the 0.2% annual level. Marginal bone loss, exceeding the third screw thread occurred in 1.8% of the implants at the last control. It appears that this type of implant configuration offers a high long-term predictability. Failures occur before, at or during the first year after abutment connection and in very short implants. Marginal bone as a whole is very stable over the years.     

Longitudinal follow-up of osseointegrated implants in patients with resected jaws

PURPOSE: To investigate the effects of bone grafting and radiotherapy on implant survival rates. MATERIALS AND METHODS: This follow-up study involved 36 patients with 180 implants who were treated between January 1989 and December 2000 by prosthodontic rehabilitation using osseointegrated implants following jaw resection. They comprised 20 patients with malignant tumors, 12 with benign tumors, and 2 patients each with osteomyelitis and cysts. RESULTS: A total of 15 implants (11 in the maxilla and 4 in the mandible) were removed for various reasons during the follow-up study. Implant survival rates were calculated using the Kaplan-Meier method; the overall survival rate for the 180 implants was 88.6%. Specific implant survival rates were as follows: in residual bone, 73.8% for the maxilla and 95.2% for the mandible; in grafted bone, 80% for the maxilla and 94.1% for the mandible; in irradiated bone, 79.7%; and in nonirradiated bone, 93.5%. DISCUSSION: Radiotherapy, a dose of 30 Gy, was performed in patients with malignant tumors but not in patients with benign tumors, cysts, or osteomyelitis. No differences were found in the results for implants placed due to jaw resection for malignant tumors and those for implants placed due to benign tumors, cysts, or osteomyelitis. Implants lost varied in length from 7 to 18 mm. Among these, loss was more frequent with shorter implants (lengths to 10 mm). CONCLUSION: The clinical results obtained in the present study compare favorably with those obtained by others. However, jaw reconstruction and rehabilitation should not be performed by the oral surgeon alone; oral and maxillofacial function should be restored using a team approach in close cooperation with specialists in prosthodontics and periodontics to improve the result of implant treatment.     

Long-term outcomes of implant-based dental rehabilitation in head and neck cancer patients after reconstruction with the free vascularized fibula flap

The study aimed at evaluating, comprehensively, implant-based dental rehabilitation in head and neck cancer patients after maxillofacial reconstruction with a vascularized free fibula flap (FFF).Data were obtained by retrospectively reviewing the medical records of patients treated in Amsterdam UMC-VU Medical Center. Dental implant survival and implant success according to the Albrektsson criteria were analyzed. Additionally, prosthetic-related outcomes were studied, with a focus on functional dental rehabilitation.In total, 161 implants were placed in FFFs, with a mean follow-up of 4.9 years (range 0.2–23.4). Implant survival was 55.3% in irradiated FFFs and 96% in non-irradiated FFFs. Significant predictors for implant failure were tobacco use and irradiation of the FFF. Implant success was 40.4% in irradiated FFFs and 61.4% in non-irradiated FFFs, mainly due to implant failure and non-functional implants. Implant-based dental rehabilitation was started 45 times in 42 patients, out of 161 FFF reconstructions (27.9%). Thirty-seven patients completed the dental rehabilitation, 29 of whom achieved functional rehabilitation. Irradiation of the FFF negatively influenced attainment of functional rehabilitation. For patients with functional rehabilitation, the body mass index varied at different timepoints: FFF reconstruction, 24.6; dental implantation 23.5; and after placing dental prosthesis, 23.9.Functional implant-based dental rehabilitation, if started, can be achieved in the majority of head and neck cancer patients after FFF reconstruction. Actively smoking patients with an irradiated FFF should be clearly informed about the increased risk for implant and prosthetic treatment failure.     

Fate of implant-retained craniofacial prostheses: life span and aftercare

PURPOSE: To assess the need for surgical and prosthetic aftercare of craniofacial prostheses supported by endosseous implants. MATERIALS AND METHODS: A retrospective clinical study assessing the surgical and prosthetic aftercare from implant placement to last visit of follow-up was performed in consecutively treated patients with implant-retained craniofacial prostheses in a department of oral and maxillofacial surgery between 1988 and 2003. RESULTS: Ninety-five patients were rehabilitated with implant-retained craniofacial prostheses. Mean follow-up was 88 months (median, 79 months). Two hundred seventy implants were placed; 153 implants in the mastoid region, 99 in the orbital region, and 18 in the nasal region. The craniofacial defects were due to genetic disorders (24 patients), trauma (12 patients), and ablative tumor surgery (59 patients). In the latter group, 104 implants (33 patients) were placed in irradiated bone. Thirty implants were lost; 8 implants in nonirradiated bone (95.2% overall implant survival rate; mastoid, 95.7%; orbit, 94.1%; nose, 87.5%) and 22 implants in irradiated bone (78.8% overall implant survival rate; mastoid, 86.2%; orbit, 73.8%; nose, 90.0%). Irrespective of the craniofacial defect, on average every 1.5 to 2 years a new facial prosthesis was made, mostly for reasons because of discoloration (31.2%), problems with attachment of the acrylic resin clip carrier to the silicone (25.3%), rupture of the silicone (13.3%), or bad fit (10.9%). Severe skin reactions around implants or beneath prostheses were only observed in the orbital region. CONCLUSION: Implant-retained craniofacial prostheses are a reliable treatment option for the restoration of craniofacial defects. The need for surgical aftercare was minor, and prosthetic aftercare predominantly consisted of making new prostheses.     

Survival analysis and clinical evaluation of implant-retained prostheses in oral cancer resection patients over a mean follow-up period of 10 years

STATEMENT OF PROBLEM: Dental implants have been increasingly used for prosthodontic rehabilitation of patients following oral tumor resection and postsurgical radiotherapy. However, only a few long-term studies have examined the implant survival rate and other factors related to prosthodontic treatment in oral tumor resection patients. PURPOSE: The purpose of this study was to evaluate the long-term survival of dental implants and implant-retained prostheses in oral cancer resection patients. MATERIAL AND METHODS: Ninety-three patients (63 men, 30 women) with a mean age of 59 years (range of 26-89 years) received 435 implants after the resection of a head and neck tumor. Twenty-nine patients received postsurgical radiotherapy prior to implant placement. The factors related to implant survival or failure were monitored over a mean observation period of 10.3 years (range of 5 to 161 months). Prosthodontic rehabilitation was evaluated with respect to the rates of technical failures and complications. Data were analyzed using a Kaplan-Meier curve and comparisons were made with the log-rank test or the Wilcoxon test (a=.05). RESULTS: Of the 435 implants, 43 implants were lost; the cumulative survival rate was 92%, 84%, and 69% after 3.5, 8.5, and 13 years, respectively. Twenty-eight implants in 6 patients were counted as lost since the patients had died. Twenty-nine irradiated patients received 124 implants, of which 6 implants were lost prior to prosthodontic rehabilitation. In 68 patients with 78 rigid bar-retained dentures, only minor technical complications were identified. However, all 25 fixed implant-supported restorations had no technical component failures and did not require technical maintenance. CONCLUSIONS: This study demonstrates that implant-retained and -supported prostheses in oral cancer resection patients, irrespective of the cancer treatment procedure, show lower long-term survival rates than those in patients without prior cancer surgery. Rigid fixation of the implant-supported prosthesis appears to minimize the complication rates. The poor implant survival rate was due to the higher mortality rate among these patients, and not to a lack of osseointegration.     

Oral rehabilitation with dental implants after cancer treatment

Background: Patients who undergo surgical management of oral cancer may greatly benefit from an implant‐supported prosthesis. This study reports on the clinical experience of dental implant placement in patients following resection of oral cancer over a 15‐year period. Controversies including the use of dental implants in irradiated tissues, and hyperbaric oxygen treatment will also be discussed. Methods: Thirty‐one patients who had dental implants placed as part of their oral rehabilitation between 1992 and 2007 were investigated. Demographic data and factors including implant survival, type of prosthesis provided, radiotherapy and the hyperbaric oxygen therapy were analysed. Results: In this retrospective study, there was a retention rate of 110 implants from a total of 115 implants placed. A high rate of implant retention was found, with 5 implant failures from a total of 115 implants placed. The 5 failed implants occurred in free flap bone that had been irradiated. Conclusions: Dental implants provide an important role in the oral rehabilitation of oral cancer patients. There may be an increased risk of implant failure in free flap bone that has been irradiated.     

应用引导骨再生及游离龈移植术改善种植失败区域软硬组织条件后再次种植修复的临床观察（附1例报告）

种植体周围炎是发生在种植体周围软硬组织上的炎症性破坏性疾病,是种植体常见的生物学并发症,严重者可导致种植体周围骨丧失甚或种植失败,软硬组织缺损往往是种植失败区域再次种植修复所面临的难点。如何重建种植体失败区域软硬组织条件是临床医生关注的焦点问题。文章展示了1例罹患种植体周围炎患者,在取出无法保存的种植体后采用引导骨再生结合游离龈移植技术进行种植失败区域的软硬组织增量,创造再次种植修复所需的条件,以期为再次种植修复的成功,包括种植体的健康、稳定及正常行使功能提供先决条件。本病例亦可为类似病例的临床处置提供一定经验的积累。     

Evaluation of patient and implant characteristics as potential prognostic factors for oral implant failures

PURPOSE: The purpose of this study was to evaluate patient, implant, and treatment characteristics to identify possible prognostic factors for implant failure. MATERIALS AND METHODS: Out of a database with different dental implant treatment protocols, a research database of 1 randomly selected implant per patient was created. The database consisted of 487 implants. Of these, 80 were withdrawn, 36 failed, and 371 remained successful during a 5-year follow-up period. Potential risk factors were evaluated by chi-square tests and post hoc analyses. RESULTS: Significant or strongly significant differences were found regarding implant failures as a result of jawbone quality, jaw shape, implant length, treatment protocol, and combinations of jawbone-related characteristics. Responsible clinics and number of implants supporting the restoration were factors that could not be associated with implant failure. DISCUSSION: Implant failures in this study were more often seen when negative patient-related factors were present. Approximately 65% of the patients with a combination of the 2 most negative bone-related factors (jawbone quality 4 and jaw shape D or E) experienced implant failure. However, only 3% of the patients had this combination. Implant length, the only implant-related factor evaluated, was also significantly correlated with the success rate, but implant length could also be regarded as a result of the jawbone volume available. Another negative patient-related factor was the treatment protocol; however, in most cases this was also indirectly or partly related to the status of the jawbone available for implant placement. CONCLUSION: Patient selection appears to be of importance for increasing implant success rates.     

放疗对狗下颌纯钛种植体与骨接触作用的影响

目的:观察放疗对狗下颌纯钛种植体与骨接触作用的影响。方法:8只成年雄性杂种狗,拔除双侧下颌第3、4前磨牙和第1磨牙,形成无牙区。拔牙后3个月,用电子直线加速器照射一侧下颌无牙区,单一剂量15Gy。另一侧不接受照射,作为对照。放疗后3个月,狗双侧下颌无牙区各植入纯钛种植体4枚,其中两枚种植体无任何辅助治疗措施。种植术后1.5个月和3个月分别处死2只动物取材。结果:放疗侧种植体的种植体-骨接触率与对照侧相比,有明显下降,在统计学上有显著差异(P=0.0001<0.01);放疗后种植体周围骨小梁体积百分比具体数值下降,统计学上差异不明显(P=0.071>0.05)。结论:放疗会影响狗下颌纯钛种植体与骨的接触作用。     

Dental implant treatment for two adjacent missing teeth in the maxillary aesthetic zone: a comparative pilot study and test of principle

Aim: The aim of this prospective comparative pilot study was to evaluate hard and soft peri‐implant tissues in patients with a missing adjacent central and lateral upper incisor treated with either one implant and an implant crown with a cantilever or two implants with solitary implant crowns up to 1 year after functional loading. Material and methods: In the “Implant–cantilever group”, five patients were treated with one dental implant in the region of the central incisor (NobelReplace Groovy Regular Platform). In the “Implant–implant group”, five patients were treated with two adjacent dental implants: at the position of the central incisor (NobelReplace Groovy Regular Platform) and at the position of the lateral incisor (NobelReplace Groovy Narrow Platform). Implant survival, pocket probing depth, papilla index, marginal bone level and patient satisfaction were assessed during a 1‐year follow‐up period. Results: No implants were lost during the 1‐year follow‐up. Mean pocket probing values of the implants were comparable between the two groups. Papilla index scores in both groups were relatively low, pointing towards a compromised papilla. Marginal bone loss was minimal and comparable between the groups. Patient satisfaction was very high in both groups. Conclusion: In this 1‐year prospective comparative study, no large differences in hard‐ and soft‐tissue levels could be shown between patients with a missing central and lateral upper incisor treated with either one implant and an implant crown with a cantilever or two implants with solitary implant crowns. To cite this article:
Tymstra N, Raghoebar GM, Vissink A, Meijer HJA. Dental implant treatment for two adjacent missing teeth in the maxillary aesthetic zone: a comparative pilot study and test of principle.
Clin. Oral Impl. Res. 22 , 2011; 207–213.
doi: 10.1111/j.1600‐0501.2010.02017.x     

Clinical outcome of overdenture treatment on two nonsubmerged and nonsplinted Astra Tech Microthread implants

Background: The use of two implants for mandibular overdenture stabilization improves the patients' comfort and well‐being. This treatment could be more cost‐effective if surgery and prosthetic treatment could be performed by one clinician in the normal setting of a dental clinic. Purpose: The aim of this retrospective clinical study was to describe implant success, restorative outcome, and the patients' opinion of mandibular overdenture treatment on two early‐loaded, nonsplinted Astra Tech TiOblast Microthread? (Astra Tech Dental, Mölndal, Sweden) implants. Materials and Methods: Thirty‐seven consecutive patients treated with implant‐supported mandibular overdentures were invited for a clinical examination. Implant survival, marginal bone level, quality of implant and prosthetic treatment, and the patients' opinion by means of questionnaires were scored. Results: Thirty‐four patients attended the examination. Two implants were lost in one patient and the failure rate for the total group of patients was 3%. As 8 of the 33 remaining patients were still in the provisional loading stage, they were not included in the final clinical and radiographic examination. Based on 25 patients and 50 implants with a mean follow‐up of 18.8 months (range 4–33), implant positioning and occlusion/articulation scored perfect in 74 to 80% of the cases. Retention of the dentures was rated perfect in 80%, but 20% needed minor activation of the attachments, 20% showed signs of abrasion, and 20% had already been repaired. The average marginal bone level was 0.8 mm below the reference point. The mean pocket depth was 2.1 mm, and 54% of the peri‐implant tissues were free of bleeding. The patients were appreciative of the work carried out by their dentist and they indicated a significant improvement in their well‐being and quality of life. Conclusions: It can be concluded that the Astra Tech implant system was successfully used by the general dentist both surgically and prosthetically with minimal implant failures and prosthetic complications and that this led to high levels of patient appreciation and overall satisfaction.     

Nine- to fourteen-year follow-up of implant treatment. Part I: implant loss and associations to various factors

Objectives: The aim of the present study was to evaluate the long‐term result of implant therapy, using implant loss as outcome variable. Material and Method: Two hundred and ninty‐four patients had received implant therapy (Brånemark System^®) during the years of 1988–1992 in Kristianstad County, Sweden. The patients were recalled to the speciality clinic 1 and 5 years after placement of the suprastructure. Between 2000 and 2002, 9–14 years after implant placements, the patients were again called in for a complete clinical and radiographic examination. Results: Two hundred and eighteen patients treated with 1057 implants were examined. Twenty‐two patients had lost 46 implants and 12 implants were considered “sleeping implants”. The overall survival rate was 95.7%. Implant loss appeared in a cluster in a few patients and early failures were most common. Eight patients lost more than one fixture. A significant relationship was observed between implant loss and periodontal bone loss of the remaining teeth at implant placement. Maxillary, as opposed to mandibulary implants, showed more implant loss if many implants were placed in the jaw. A significant relationship between smoking habits and implant loss was not found. Conclusion: A history of periodontitis seems to be related to implant loss.     

Early experience with Wide-Platform Mk II implants. Part I: Implant survival. Part II: Evaluation of risk factors involving implant survival

Part I of this study describes the survival of a wide-platform, wide-diameter implant (Wide-Platform Mk II). Beginning in January 1997, 85 Wide-Platform Mk II implants were placed in the jaws of 63 patients (35 males and 28 females). Male patients experienced 10 implant failures, and female patients lost 9 implants. The mean time of implant follow-up was 286 days (median, 280), with a maximum of 734 days and a minimum of 0 days. Implant loss was 19% in the mandible and 29% in the maxilla. Kaplan-Meier analysis showed a probability of implant failure after 1 year of 0.649 (confidence interval, 0.455 to 0.926) in the maxilla and of 0.751 (confidence interval, 0.616 to 0.915) in the mandible. No apparent relationship was noted between implant survival and implant length. Part II of this study evaluated the association between the survival of a new implant design and a number of potential risk factors. A retrospective chart review was conducted for all patients who received Wide-Platform Mk II implants and who agreed to allow a medical records review for research purposes. Kaplan-Meier survival curves were used to assess the probability of implant survival relative to time. The relationships between implant survival and implant location, history of tobacco use, current tobacco use, sinus grafting, bruxism, and root canal therapy were assessed by Cox proportional hazards modeling. Although the hazard ratio showed an increased risk of implant failure with some factors, particularly a history of root canal therapy in the site of implant placement (hazard ratio 3.2, P = .10), none of the factors were statistically significant. The Wide-Platform Mk II implant used in this population group was associated with a high failure rate, but the failure rate was not related to any specific risk factors reviewed.     

Immediate versus delayed loading of dental implants in the maxillae of minipigs: follow-up of implant stability and implant failures

PURPOSE: To assess the course of the stability and the failure rate of dental implants placed in the partially edentulous maxillae of minipigs. MATERIALS AND METHODS: Three months after tooth removal, implants were placed in 9 minipigs. Six implants (XiVE; Friadent, Mannheim, Germany) were placed on each side of the posterior maxilla after preparation of the implant sites either by an osteotome technique or with spiral drills. Implant stability was assessed by resonance frequency analysis (RFA) at the time of placement, at second-stage surgery (which took place after a healing periods of 1, 2, 3, 4, or 5 months), and after a loading period of 6 months. RESULTS: Implant stability was significantly influenced by the healing period (P = .007). Implant stability decreased after 1 to 3 months of healing for both of the placement techniques and increased after a healing period of 4 months. After implant site preparation by an osteotome technique, 6 of 12 immediately loaded implants, 18 of 24 implants loaded after healing periods of 1 to 3 months, and 1 of 18 implants loaded after a healing period of 4 or 5 months were lost. After implant site preparation using spiral drills, 7 of 12 immediately loaded implants, 12 of 24 implants loaded after healing periods of 1 to 3 months, and 2 of 18 implants loaded after healing periods of 4 or 5 months were lost. Broad overlapping of confidence intervals for the number of implant failures revealed that there was no relevant difference between immediate and early functional loading for either of the 2 techniques. DISCUSSION AND CONCLUSION: Implant loading after healing periods of 1 to 3 months did not improve implant survival compared to immediate loading in the posterior maxillae of minipigs. Not until a healing period of 4 months was reached did implant stability begin to increase. Only when functional loading was started at this point in time was maximal implant survival achieved.     

Restoration of irradiated patients using osseointegrated implants: Current perspectives

Statement of problem. The success rates of osseointegrated implants used to restore patients who were irradiated for head and neck tumors are influenced by radiation-induced changes in the hard and soft tissues.Purpose. This article examined, by review of the literature, current perspectives on the restoration of irradiated patients using osseointegrated implants.Results. In published reports that investigated both intraoral and extraoral applications, irradiation decreased implant success rates and the amount of reduction was dependent on the location within the craniofacial skeleton. The limited number of implants and patients in these studies precludes definitive conclusions regarding the efficacy of placing implants into irradiated tissues. The implants placed into the irradiated anterior mandible have demonstrated an acceptable implant success rate of 94% to 100% with a minimal risk of osteoradionecrosis. The efficacy of implants in the posterior mandible has not been examined. Implant success rates ranged from 69% to 95% in the irradiated maxilla for intraoral applications. Extraoral applications demonstrated excellent implant success rates in the temporal bone (91% to 100%). The rates in the anterior nasal floor have varied from 50% to 100%. The implant success rates in the frontal bone decreased as the length of the studies increased (96% to 33%). The long-term efficacy of implants in the irradiated frontal bone is poor. (J Prosthet Dent 1998;79:641-7.)     

Early complete failures of fixed implant-supported prostheses in the edentulous maxilla: a 3-year analysis of 17 consecutive cluster failure patients

Background Clusters of implant failures in the edentulous maxilla seem to occur in some patients. To create groups for analysis with higher numbers of these patients implies large original groups for inclusion. Purpose The aim of this study was to retrospectively describe and compare a group of “cluster failure patients” with randomly selected patients treated in the edentulous maxilla. Materials and Methods From a group of 1,267 consecutively treated patients in one clinic, all patients presenting failing fixed implant‐supported prostheses within the first 3 years of follow‐up were included. All patients were treated with turned titanium implants using two‐stage surgery. A control group of equal number of patients were created for comparison. Data on patients were retrospectively retrieved from their records, and compared. Results Seventeen patients (1.3%) met the inclusion criteria in the entire group. The bone resorption index revealed less bone quantity in the study group (p < .05) during implant placement, but there was no difference regarding primary implant stability at first‐stage surgery. The distribution of short and long implants showed relatively higher number of short implants in the study group (p < .05), and more patients had a presurgical discussion on the risk of implant failure prior to treatment in this group (p < .05). Only 5 out of 102 implants (4.9%) were lost before prosthesis placement as compared to 38 and 25 lost implants during the following two years in the study group. Smoking habits and signs of bone loss related to periodontitis in the lower dentition were more frequent in the study group, but did not reach a significant level (p > .05). Conclusion The results indicate that bone quantity, reflected in fixture length, has a significant impact on increased implant failure risk. Other factors of interest as predictors for implant failures could be smoking habits and also possibly signs of periodontitis in the opposing dentition.     

Multicenter Randomized Clinical Trial: Early Loading of Implants in Maxillary Bone

Purpose: The aim of this study was to show prognostic equivalence between implant loading in the maxilla after 12 weeks versus 4 weeks. Materials and Methods: One hundred four patients, from four centers in this open‐labeled randomized multicenter prospective controlled clinical trial, were assigned to either 12 weeks or 4 weeks of unloaded healing. Two hundred sixty‐nine implants (sand blasted large‐grid, acid etched [SLA] surface, ≥4.1 mm diameter; ≥10 mm length) were inserted and evaluated during an individual 5‐year follow‐up. Primary outcome was implant success after 12 months; prognostic equivalence was characterized by a maximum difference of ±5% in implant failure rates. Results: Implant‐wise 1‐year failure rates were estimated 3.1% (5/163 implants) in the 4 weeks group versus 3.6% (4/112 implants) in the 12 weeks group (95% confidence interval [CI] for the difference ?3.2 –+4.2%); implant‐wise evaluation demonstrated statistically significant prognostic equivalence of 4 and 12 weeks loading. Patient‐wise 1‐year failure rates were estimated 6.7% (n = 4 patients) in the 4 weeks group versus 5.1% (n = 2 patients) in the 12 weeks group (95% CI for the difference ?9.6 –+6.5%). All implant failures occurred within the first 3 months of the individual observation period. Prior bone augmentation, underdimensioned drilling, bone quality, implant type, implant length, implant diameter, residual teeth, and fixing of the restoration did not reveal associations with the implant outcome: trial site, posterior jaw region, and splinting were associated with a higher failure rate. Resonance frequency analysis did not serve as a predictor of implant failures at the time of implant insertion. Conclusion: Loading of standard SLA implants in the maxilla 4 weeks versus 12 weeks after insertion resulted in statistically equivalent failure patterns within a 1‐year follow‐up period; nevertheless, the observed patient‐wise failure patterns of the interim analysis requires further understanding of patient‐individual aspects of the early loading concept.