Prognosis of immediately loaded implants and their restorations: a systematic literature review

Immediate loading of oral implants has become popular because of the increasing demands of a shortened treatment time. This literature review evaluates the prognosis of immediately loaded implants and their restorations with immediate or delayed implant placement. Special attention was given to the impact of type of jaw, bone quality, implant length, time of implant placement and type of restoration. An electronic (PubMed) and a manual search in relevant journals were conducted until February 2012. Only publications in English, in peer-reviewed journals, were considered. Nine studies met the inclusion criteria: five studies dealt with fixed restorations, two studies with removable rehabilitation of edentulous jaws and two studies dealt with partially edentulous patients. Implant survival rates ranged from 95·8% to 100%, implant success rates in the treatment for the mandible from 79% to 100% and restoration survival rates for both jaws from 96·4% to 100%. Within the limits of this review, appropriate patient selection, primary implant stability, splinting of implants and the expertise of surgeons seem to be important for the prognosis of immediately loaded implants and their restorations. Good bone quality and use of long implants appear to play a role. However, careful interpretation is required because conclusions are based on articles with low level of evidence. While immediate loading of oral implants in the mandible shows encouraging and predictable results, further multicenter randomised controlled clinical trials with sufficient statistical power are needed to examine (i) the outcome of immediately loaded implants in the maxilla and (ii) the outcome of immediate loading of immediately placed implants.     

Clinical trials in zirconia: a systematic review

Summary Zirconia is unique in its polymorphic crystalline makeup, reported to be sensitive to manufacturing and handling processes, and there is debate about which processing method is least harmful to the final product. Currently, zirconia restorations are manufactured by either soft or hard‐milling processes, with the manufacturer of each claiming advantages over the other. Chipping of the veneering porcelain is reported as a common problem and has been labelled as its main clinical setback. The objective of this systematic review is to report on the clinical success of zirconia‐based restorations fabricated by both milling processes, in regard to framework fractures and veneering porcelain chipping. A comprehensive review of the literature was completed for in vivo trials on zirconia restorations in MEDLINE and PubMed between 1950 and 2009. A manual hand search of relevant dental journals was also completed. Seventeen clinical trials involving zirconia‐based restorations were found, 13 were conducted on fixed partial dentures, two on single crowns and two on zirconia implant abutments, of which 11 were based on soft‐milled zirconia and six on hard‐milled zirconia. Chipping of the veneering porcelain was a common occurrence, and framework fracture was only observed in soft‐milled zirconia. Based on the limited number of short‐term in vivo studies, zirconia appears to be suitable for the fabrication of single crowns, and fixed partial dentures and implant abutments providing strict protocols during the manufacturing and delivery process are adhered to. Further long‐term prospective studies are necessary to establish the best manufacturing process for zirconia‐based restorations.     

Systematic review of survival rates for immediately loaded dental implants

The primary goal of this paper was to determine the survival rate of immediately loaded (IL) dental implants based on a systematic review of the literature. Secondary goals were to determine the influence of several factors on the implant survival rate, such as the type of reconstruction, implant location, and implant surface characteristics. An electronic search of databases was performed, in addition to a hand search of the most relevant journals. All relevant articles were independently screened according to specific inclusion criteria. The selected papers were reviewed. The literature search yielded 270 applicable articles up to December 2005. Of these, 71 met the inclusion criteria for qualitative data analysis. Eight articles were randomized controlled trials. The overall implant survival rate for the included studies was 96.39%. The database included 10,491 IL implants placed in 2,977 patients, with a maximum follow-up of 13 years. IL is well documented and predictable for the edentulous mandible (overdentures and full-arch prostheses) and for maxillary single crowns. Fewer data were found for maxillary full-arch reconstructions, fixed partial prostheses, and mandibular single crowns. For the latter two types of reconstructions, implants placed in anterior sites generally displayed a higher survival rate versus those placed in posterior sites. Rough surfaces displayed a higher survival rate than machined surfaces in all types of reconstructions. Most failures (97.1%) occurred within the first 12 months of loading. This review showed that it is possible to apply IL with excellent survival rates. Implant micromorphology and careful patient selection may affect treatment outcomes.     

上颌窦底微创提升的短期临床疗效评价

目的：通过临床试验评估一种上颌窦底微创提升技术的疗效。方法试验组11例患者的上颌后牙区行上颌窦底微创提升技术并同期植入短种植体14枚。对照组10例患者进行了使用扩孔钻的上颌窦冲顶技术并同期植入短种植体13枚。两组患者术后6个月行暂冠修复,进行咬合训练及软组织塑形,3个月后永久修复。术后定期复诊,检查患者的上颌窦、种植体骨结合情况,并使用锥形束CT（CBCT）测量骨增量水平。结果试验组及对照组均无种植体松动、脱落及上颌窦炎发生,CBCT显示种植体与周围组织形成良好的骨性结合。经2~28个月随访观察,临床效果良好。试验组和对照组平均窦底垂直骨增量分别为5.87和5.45 mm。结论上颌窦底微创提升联合短种植体同期植入是一种创伤小、操作简单、行之有效的上颌后牙区种植外科技术,可用于上颌窦底垂直骨量严重不足,余留牙槽骨高度不足4 mm的病例。     

Prosthodontic considerations designed to optimize outcomes for single-tooth implants. A review of the literature

Background: The aim of this study was to review the literature on the restoration of single‐tooth implants, and to develop evidence‐based conclusions to optimize aesthetic, biologic and patient‐related outcomes. Methods: An electronic and hand search was conducted using the search terms ‘dental implants, single‐tooth; dental restoration, temporary; dental impression materials; dental impression technique; dental prosthesis, implant‐supported; dental prosthesis design; dental abutments; dental occlusion; maintenance; survival; and survival analysis’. Resultant titles were screened, and full text was obtained where relevant. The authors selected the most appropriate articles, giving preference to systematic reviews and long‐term, patient‐based outcome data. Results: Thirty‐nine articles were selected and critiqued by the authors. Conclusions: There was strong suggestion by several authors that peri‐implant soft tissue aesthetics can be sculpted through provisional restoration contour, but there are no clinical outcome studies to define or support this claim. Laboratory studies demonstrate that pick‐up type impression copings in conjunction with elastomeric impressions are the most accurate means for transferring implant position to a dental cast. Laboratory and finite‐element analysis studies suggest implants with an internal‐type connection show improved stress distribution, but supportive clinical data are lacking. The authors of this review favour a screw‐retained prosthesis for retrievability. Clinical and histological studies show that gold, titanium and zirconia ceramic abutment materials exhibit excellent biological responses, although there is insufficient data on the clinical service provided by zirconia as an implant‐substructure material. The literature does not associate any particular occlusal scheme with superior clinical outcomes. Implant‐borne single crowns offer comparable clinical service to tooth‐borne fixed dental prostheses. However, single‐tooth implant restorations are associated with an increased incidence of biological and technical complications.     

Biologic outcome of implant-supported restorations in the treatment of partial edentulism. part I: a longitudinal clinical evaluation

Abstract: The purpose of this study was to predict the outcome of implant restorations in the treatment of partial edentulism, taking into account implant interdependency and the effect of several confounding variables. Between December 1982 and June 1998, 1956 Brånemark system^® implants (1212 and 744 in the maxilla and mandible, respectively, 846 distal to first premolars) were installed in 660 patients (248 males) at the Department of Periodontology of the University Hospitals of the Catholic University of Leuven. Of the 810 restorations installed at the Department of Prosthetic Dentistry of the same hospital, 235 were single crowns, 166 were supported by implants and teeth and 409 were free-standing fixed partial prostheses. An additional 87 restorations was placed in private dental offices and were not included. The patients were followed from implant installation until June 1999. The estimated cumulative survival rates were 91.4% for all implants and 95.8% for all restorations over a period of 16 years. Estimated cumulative survival rates from loading for implant-tooth connected and free-standing implants were, respectively, 93.6% and 97.2%. Neither jaw site nor implant position (anterior–posterior) had any significant effect on the outcome. Short implant length, high number of implants per patient, low number of implants per prosthesis, implants loaded by acrylic-veneered restorations and implants combined with bone grafting present a higher risk hazard for implant failure. The idea of not splinting the implants in a fixed partial prosthesis is promising but needs replication before accepting it.     

Dental implant placement through impacted teeth or residual roots as an alternative to invasive extraction surgeries: a systematic literature review

This work systematically reviews dental implant placement through impacted teeth or residual roots, as an alternative to invasive extraction surgeries, evaluated in terms of survival rates, marginal bone loss, surgical, and prosthetic complications. The authors conducted an electronic search of four databases up to September 2020; also a complementary handsearch was carried out. The quality of the included studies was assessed using a protocol for assessment of risk of bias in exposure studies. Ten studies fulfilled the inclusion criteria and were analysed. A total of 44 patients received 62 dental implants and were monitored for a minimum of 12-months follow-up. An overall mean implant survival rate was 90.32%, reporting 97.56 % for dental implants through impacted teeth and 76.19% through residual roots. No surgical or prosthetic complications were reported. Placing dental implants through impacted teeth may offer a valid therapeutic option for implant-supported restorations in patients for whom surgery and orthodontic traction are not possible, and/or patients who refuse to undergo more invasive extraction surgery. Moreover, additional caution is recommended when placing implants through retained root fragments, as this may involve long-term risk. Further research generating long-term data are needed to confirm these findings.     

Clinical outcomes of titanium-zirconium alloy narrow-diameter implants for single-crown restorations: a systematic review and meta-analysis

Evidence is limited on whether titanium-zirconium alloy, narrow-diameter implants (Ti-Zr NDIs) have promising clinical outcomes when used to support single crowns. The purpose of this systematic review and meta-analysis was to evaluate clinical evidence, including survival rates, success rates, and marginal bone loss (MBL) on Ti-Zr NDIs that support single crowns. An extensive search was performed in the databases of PubMed/MEDLINE, Scopus, Embase, and the Cochrane Library for studies published in English up to April 2022. Only peer-reviewed clinical studies with at least 10 patients and a follow‐up time of at least 12 months were included. Risk of bias in each study was assessed and data extraction was carried out independently by two reviewers. The outcome variables were survival rates, success rates, and MBL. The search returned 779 results. Eight studies were identified for qualitative analysis and seven for quantitative synthesis. Overall, a total of 256 Ti-Zr NDIs were included. Cumulative implant survival rates and success rates were 97.5% (95% confidence interval (CI): 94.5% to 98.9%) and 97.2% (95% CI: 94.2% to 98.7%), respectively, over a maximum follow-up period of 36 months, with no difference between Ti-Zr NDIs and commercial pure titanium (cpTi) implants. Cumulative mean (SD) MBL was 0.44 (0.04) mm (95% CI: 0.36 to 0.52) after one year. Meta-analysis of MBL indicated a mean difference of 0.02 mm (95% CI: -0.23 to 0.10), with no differences between Ti-Zr NDIs and cpTi implants. Short-term results of Ti-Zr NDIs for single-crown restorations are quite promising, although the number of published studies and follow-up periods are insufficient to determine the real benefit for single crowns. Long-term, follow-up clinical studies are needed to verify the excellent clinical performance of Ti-Zr NDIs.     

Prosthetic outcome of cement-retained implant-supported fixed dental restorations: a systematic review

The aim of the article is to assess the current literature in terms of the prosthetic outcome of cement-retained implant-supported fixed restorations, as well as to determine the type of cement that can be recommended for clinical application. A review of the literature published up to May 2010 was conducted to identify clinical studies about cement-retained implant-supported fixed restorations. The search strategy applied was a combination of MeSH terms and free text words, including the following keywords: implants, implant-supported fixed dental prostheses (FDPs), bridges, implant-supported single crowns (SCs), cement-retained, cement fixation, cement, cementation, cement failure, retention, and loss of retention, technical complications, mechanical complications, prosthetic complication, retrievability and maintenance. Thirty-two studies met the inclusion criteria. The studies were divided into two categories: 15 short-term clinical studies with an observation period of less than 5 years, and 17 long-term clinical studies with an observation period of 5 years and more. The most common technical complications of cement-retained implant-supported fixed restorations were loss of retention, chipping and abutment screw loosening. The results of the current review revealed no guidelines about cement or cementation procedures. It may be stated that despite the questionable retrievability of cement-retained implant-supported fixed restorations, this treatment modality is a reliable and effective option, especially for implant-supported SCs and short-span FDPs. The literature does not provide accurate information about the clinical outcome of cement-retained implant-supported fixed restorations nor about the ideal type of cement that facilitates stability and maintains retrievability. Standardised randomised clinical trials will provide valuable information to this issue.     

Effect of the Timing of Restoration on Implant Marginal Bone Loss: A Systematic Review

Background: The advancement in implant dentistry has allowed shortened treatment time by restoring the implants earlier. Whether the timing of restoration has an impact on implant marginal bone level has not been systematically analyzed. The aim of this study is to compare marginal bone loss (MBL) between implants that were restored with the following protocols: 1) immediate restoration/loading (IR/L); 2) early loading (EL); and 3) conventional loading (CL). Methods: An electronic literature search from three databases (until November 2011) and a hand search in implant‐related journals were conducted. Clinical human studies in English language that had reported a comparison of MBL between implants with IR/L, EL, or CL with ≥12‐month follow‐up were included. In addition, the minimal number of implants had to be 10 for each group. Implants with both immediate placement (IP) and delayed placement (DP) were included and analyzed separately. An assessment of the publication bias for the included randomized clinical trials (RCTs) was performed. Results: The initial search resulted in 1,640 articles, of which 27 articles in full text were further evaluated for eligibility. Finally, 11 studies (eight RCTs, two controlled clinical trials, and one retrospective study) were qualified and classified into four groups: 1) IR/L + DP versus CL + DP (n = 6 articles); 2) IR + DP versus EL + DP (n = 2 articles); 3) EL + DP versus CL + DP (n = 1 article); and (4) IL + IP versus CL + IP (n = 2 articles). A meta‐analysis performed for group 1 showed 0.09 mm (95% confidence interval = ?0.27 to 0.09 mm) difference in the mean MBL, favoring the IR/L protocol but without significant difference (P = 0.33). No significant difference in MBL was found for groups 2 through 4 after adjusting for the implant placement level. The eight RCTs were determined to be at moderate‐to‐high risk of publication bias. Conclusions: This meta‐analysis does not show an effect of the timing of restorations on implant MBL. The selection of restoration protocols should be based on factors other than MBL.     

Implant survival rates after maxillary sinus augmentation

Implant therapy in the atrophic posterior maxilla becomes challenging in the presence of reduced maxillary bone height. Sinus augmentation can be performed for resolving this condition prior to implant placement. The aim of this article was therefore to evaluate implant survival rates in the grafted sinus taking into account the influence of the implant surface, graft material, and implant placement timing. A systematic review of the literature was performed. Articles retrieved from electronic databases were screened using specific inclusion criteria, and data extracted were divided according to: graft material (autogenous, non‐autogenous, composite graft), implant surface (machined or textured), and implant placement (simultaneous with grafting or delayed). Fifty‐nine articles were included. Survival rates for implants placed in grafts made of bone substitutes alone and grafts of composite material were slightly better than the survival rates for implants placed in 100% autogenous grafts. Over 90% of implants associated with non‐autogenous grafts had a textured surface. Textured surfaces achieved better outcomes compared with machined surfaces, and this was independent of the graft material. Simultaneous and delayed procedures had similar outcomes. It may be concluded that bone substitutes can be successfully used for sinus augmentation, reducing donor‐site morbidity. Long‐term studies are needed to confirm the performance of non‐autogenous grafts. The use of implants with a textured surface may improve the outcome in any graft type.     

Systematic review of survival rates for implants placed in the grafted maxillary sinus

Based on a systematic review of the literature from 1986 to 2002, this study sought to determine the survival rate of root-form dental implants placed in the grafted maxillary sinus. Secondary goals were to determine the effects of graft material, implant surface characteristics, and simultaneous versus delayed placement on survival rate. A search of the main electronic databases was performed in addition to a hand search of the most relevant journals. All relevant articles were screened according to specific inclusion criteria. Selected papers were reviewed for data extraction. The search yielded 252 articles applicable to sinus grafts associated with implant treatment. Of these, 39 met the inclusion criteria for qualitative data analysis. Only 3 of the articles were randomized controlled trials. The overall implant survival rate for the 39 included studies was 91.49%. The database included 6,913 implants placed in 2,046 subjects with loaded follow-up time ranging from 12 to 75 months. Implant survival was 87.70% with grafts of 100% autogenous bone, 94.88% when combining autogenous bone with various bone substitutes, and 95.98% with bone grafts consisting of bone substitutes alone. The survival rate for implants having smooth and rough surfaces was 85.64% and 95.98%, respectively. Simultaneous and delayed procedures displayed similar survival rates of 92.17% and 92.93%, respectively. When implants are placed in grafted maxillary sinuses, the performance of rough implants is superior to that of smooth implants. Bone-substitute materials are as effective as autogenous bone when used alone or in combination with autogenous bone. Studies using a split-mouth design with one variable are needed to further validate the findings.     

Success of immediate loading implants compared to conventionally‐loaded implants: a literature review

The purpose of this systematic literature review was to compare the clinical performance between conventionally‐ (delayed) and immediately‐loaded implants. A literature search of studies published between 1995 and 2012 was performed using several electronic databases and the following key words: “immediate loading”, “dental implants”, “immediate function”, “early loading”, “oral implants”, “immediate restoration”, and “systematic review” was performed. The electronic search was supplemented with hand‐searching in dental journals and cross‐referencing within the selected articles. Studies were considered for inclusion if they analyzed the success of the immediate loading protocol for implants, with emphasis given to randomized, controlled clinical trials. Among the clinical studies extracted from the literature, 120 studies met the inclusion criteria and were included in this systematic review. These studies included trials that involved yielded consistent results of success rates of immediately‐loaded implants comparable to those known from conventionally‐loaded implants, which were subjected to the immediate loading protocol or other loading protocols. According to the findings, there is evidence to suggest that immediate loading protocols demonstrate high implant survival rates and could be cautiously recommended for certain clinical situations. However, studies with a high level of evidence, especially randomized, controlled trials, performed over a longer timeframe are required to show a clear benefit over conventional and other loading types.     

How to treat two adjacent missing teeth with dental implants. A systematic review on single implant‐supported two‐unit cantilever FDP's and results of a 5‐year prospective comparative study in the aesthetic zone

To conduct a systematic review on the clinical outcome of single implant‐supported two‐unit cantilever FDP's and to conduct a 5‐year prospective comparative pilot study of patients with a missing central and lateral upper incisor treated with either a single implant‐supported two‐unit cantilever FDP or two implants with solitary implant crowns in the aesthetic zone. Medline, Embase and the Cochrane Central Register of Controlled Trials were searched (last search 1 August 2016) for eligible studies. In the comparative pilot study, an implant‐cantilever group of five patients with a single implant‐supported two‐unit cantilever FDP (NobelReplace Groovy Regular Platform) was compared with an implant‐implant group of five patients with two adjacent single implant‐supported crowns (NobelReplace Groovy Regular Platform) in the aesthetic zone. Implant survival, marginal bone level (MBL) changes, pocket probing depth, papilla index and patient satisfaction were assessed during a 5‐year follow‐up period. Five of 276 articles were considered eligible for data extraction. Implant survival ranged from 96·6% to 100%. Marginal bone level changes were higher in the anterior region than in the posterior region. Technical complications occurred more often in the posterior than anterior region. In the 5‐year comparative pilot study, no clinically significant differences in hard and soft peri‐implant tissue levels occurred between both groups. Single implant‐supported two‐unit cantilever FDP’s can be a viable alternative to the placement of two adjacent single implant crowns in the aesthetic zone. Due to technical complications, placement of two‐unit cantilever crowns in the posterior region can be considered unwise.     

即刻种植修复上前牙的临床美学疗效观察

目的：评价上颌前牙即刻种植即刻修复的临床美学效果。方法：临床选择26例上前牙残根患者,在拔牙后即刻植入Xive种植体26枚,同时接入基台行复合树脂临时冠/桥修复,6个月后,行永久性修复。种植后嘱患者按期复查,评价应用效果。结果：种植牙修复后咀嚼功能恢复良好,种植体周围软组织健康美观。修复体单冠和修复基台的接缝位于龈下,种植牙给人以从龈下长出来的视觉效果。24名患者对修复体及其临床应用效果和美观效果都评价为满意,1枚种植体发生周围炎,1颗烤瓷冠崩瓷。满意度为92.31%。结论：Xive种植体在上颌前牙缺失即刻种植即刻修复中能够获得满意的临床效果。但要注意种植中软、硬组织和修复体的美学处理。     

Multicenter retrospective study of cement-retained implant-supported anterior partial prostheses: success and restoration evaluation

PURPOSE: The aim of this multicenter study was to evaluate implant success and restorative complications of cement-retained implant-supported anterior partial prostheses in Jordan. MATERIALS AND METHODS: A retrospective study of all implants with a minimum of 1-year follow-up were used to support fixed, cement-retained restorations from April 2000 until March 2007. The cement-retained implants were loaded with either single- or multiple-tooth replacements. The Fisher exact test was performed to test the presence of any statistically significant difference in success concerning gender or arch of placement. RESULTS: Eighty-seven implants were placed in the anterior region of the mandible or maxilla in 49 patients at multiple clinical practices in Jordan. The age of the patients ranged from 17 to 85 years. Eighteen implants were placed in the mandible and 69 in the maxilla. Three maxillary implants in 2 male patients had 3-mm horizontal bone loss. Those 3 implants are still functioning and were considered surviving implants but not successful implants. Therefore, the implant cumulative survival rate for both arches and genders was 100%. The implant cumulative success rate was 95.78%. Three crowns (maxillary) were dislodged. No significant differences were revealed regarding gender or arch of placement (P > .05). CONCLUSIONS: Cement-retained implants exhibited high survival and success rates among a Jordanian population.     

Aesthetic outcome of single-tooth implant restorations following early implant placement and guided bone regeneration: crown and soft tissue dimensions compared with contralateral teeth

Objectives: The aim of this study was to compare crown and soft tissue dimensions of single-tooth implant restorations following early implant placement and guided bone regeneration (GBR) with contralateral non-restored teeth.
Material and methods: Twenty-seven patients treated by one and the same surgeon and prosthodontist to restore a single-tooth gap with a class I bone defect in the premaxilla by means of an implant-supported restoration were reviewed. Patients were examined at least 6 months following placement of the crown. All implants had been inserted 6–8 weeks following tooth extraction in conjunction with GBR. At evaluation, crown dimensions, soft tissue dimensions, clinical conditions and patients' aesthetic satisfaction were assessed by one clinician who had not been involved in the treatment.
Results: Implant-supported crowns were not significantly longer than contralateral teeth and midfacial soft tissues showed comparable levels after on average 21 months of function. Our data also indicated significant papilla loss especially at the distal aspect of the implants. As the patient's aesthetic appreciation was favourable in 88% of the cases, this appeared to be of trivial importance.
Conclusions: Favourable aesthetics may be achieved for single-tooth implant restorations following early implant placement and GBR. The impact of the latter on papilla levels, however, remains to be determined in longitudinal studies.