Survival Rates of Splinted and Nonsplinted Prostheses Supported by Short Dental Implants (≤8.5 mm): A Systematic Review and Meta-Analysis

The Effect of Prosthetic Factors on the Long-Term Survival of Dental Implants: A Narrative Review

The success of implants depends on the biological and mechanical factors of the implant, as well as on the chosen prosthesis, which has different characteristics that can affect the survival of the implant and its marginal bone levels. Therefore, when choosing the type of prosthesis, it is necessary to understand and consider each of these variables and tailor them to the relevant clinical situation. In this narrative review, we will assess the types of prostheses, their different characteristics, timing, and their impact on implant survival and marginal bone levels, as accepted in today's literature.

Impact of splinting implant-supported crowns on the performance of adjacent posterior implants: A systematic review and meta-analysis

STATEMENT OF PROBLEM

While rehabilitation with implant-supported crowns in the posterior region is widely practiced, guidance on clinical considerations when choosing between splinted or nonsplinted implant-supported crowns is limited.

PURPOSE

The purpose of this systematic review with meta-analysis was to assess whether adjacent implants with internal connections in the posterior region should be treated with splinted or nonsplinted crowns.

MATERIAL AND METHODS

The systematic review was registered on the prospective register of systematic reviews (PROSPERO) under the code, CRD42021248525. Two authors searched 4 electronic databases (PubMed, Cochrane Library, Scopus, and Web of Science) independently for articles published up to December 2023. Additionally, a hand search was conducted in the nonpeer-reviewed literature and the reference lists of included articles. Only clinical studies comparing splinted and nonsplinted hexagonal or conical internal connection adjacent implants in the posterior region were considered. A single-arm meta-analysis was conducted using RevMan. Risk of bias and quality were assessed using the Cochrane Collaboration's Tool for Assessing Risk and the Newcastle-Ottawa scale.

RESULTS

Qualitative synthesis included 17 studies, and quantitative synthesis involved 13 studies. A total of 2085 implants (1244 splinted and 841 nonsplinted) were inserted in 1027 participants, with observation times ranging from 5 months to 16 years. Thirteen studies related the type of crown retention (cemented or screw-retained). Only 2 studies related annual bone loss results considering the type of crown retention, but whether they were splinted or nonsplinted crowns and significant differences were not specified. The meta-analysis revealed no statistical differences between splinted and nonsplinted implants for biological complications (P=.95, I2=0%). However, the nonsplinted implants exhibited significantly more mechanical complications than the splinted implants (P<.001, I2=1%, RR 0.37; 95% IC [0.26-0.54]). The studies included demonstrated a low risk of bias and were of good quality.

CONCLUSIONS

Splinting was not found to affect the incidence of biological complications in posterior adjacent implants. However, more mechanical complications occurred in nonsplinted crowns than splinted ones.

The Impacted Maxillary Canine in the Adult: A Narrative Review and Implant Treatment Options

PURPOSE

The purpose of this article is to provide clinicians with options to restore the adult patient with an impacted maxillary canine using dental implants. Literature was reviewed to provide evidence for the methods suggested.

METHODS

The search strategy utilized pubmed.gov to identify articles pertinent to identified treatment options. The search used terms which included dental implants and impacted tooth, tilted implants and fixed partial prostheses, 6 mm dental implants, and 4 mm dental implants. Articles were included if they reported dental implant procedures associated with impacted canines in adults, or if they reported on the use of tilted implants, immediate implant placement at time of canine removal, or the use of short implants. Articles with less than 12 months follow up were excluded.

RESULTS

The search identified articles which included dental implants and impacted tooth (n = 142), tilted implants and fixed partial (n = 36), 6 mm dental implants (n = 182), and 4 mm dental implants (n = 162). From this search, 28 articles were collated that satisfied the inclusion criteria. The use of tilted implants had success rates ranging from 93% to 99%. Short implants had success rates ranging from 87 to 90% in the posterior maxilla. Immediate implant placement after removal of the impacted canine lacked long term reports. Two cases are included to demonstrate treatment planning using navigation to guide implant placement in an adult patient with an impacted maxillary canine.

CONCLUSIONS

The evidence-based literature concerning implant placement associated with adult maxillary canines is limited. There is evidence to support tilting implants to avoid the impacted canine, or the use of short implants splinted together to avoid the impacted tooth. Other options had insufficient data to offer support.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The Scientific Investigation Committee of the American Academy of Restorative Dentistry offers this review of the 2022 dental literature to briefly touch on several topics of interest to modern restorative dentistry. Each committee member brings discipline-specific expertise in their subject areas that include (in order of the appearance in this report): prosthodontics; periodontics, alveolar bone, and peri-implant tissues; dental materials and therapeutics; occlusion and temporomandibular disorders; sleep-related breathing disorders; oral medicine and oral and maxillofacial surgery; and dental caries and cariology. The authors focused their efforts on reporting information likely to influence the daily dental treatment decisions of the reader with an emphasis on innovations, new materials and processes, and future trends in dentistry. With the tremendous volume of literature published daily in dentistry and related disciplines, this review cannot be comprehensive. Instead, its purpose is to update interested readers and provide valuable resource material for those willing to subsequently pursue greater detail on their own. Our intent remains to assist colleagues in navigating the tremendous volume of newly minted information produced annually. Finally, we hope that readers find this work helpful in managing patients.

Comparative evaluation of short or standard implants with different prosthetic designs in the posterior mandibular region: a three-dimensional finite element analysis study

The purpose of this study is to evaluate the stress distribution of splinted or nonsplinted restorations supported by 2 short or 2 standard dental implants in the mandibular molar region using three-dimensional finite element analysis. Two standard implants (4.8 × 10mm) were placed in the mandibular molar area. Two short implants (4.8 × 6 mm) were located in the mandibular molar atrophied area. Implant-supported prostheses were simulated with splinted or nonsplinted crowns design. Vertical load of 200 N and oblique load of 100 N were applied on the central fossa and the buccal cusps. Evaluation of stress distribution in implants and peri-implant cortical bone using the finite element analysis software (Ansys, Version 2020, R2), a multipurpose computer design program. The maximum principal stress of cortical bone around the implants was higher in nonsplinted crowns when compared to splinted crowns. The stress concentration of cortical bone surrounding implants increased as the implant length decreased either splinted crowns or nonsplinted crowns. The short implants with nonsplinted crowns showed lower stresses when compared to standard implants with nonsplinted crowns. The results suggest that the nonsplinted prostheses supported by short dental implants might be considered in the molar area of the atrophic mandible.

Short implants compared to regular dental implants after bone augmentation in the atrophic posterior mandible: umbrella review and meta-analysis of success outcomes

PURPOSE

To assess the body of evidence of short versus regular implants after bone augmentation (BA) in the atrophic posterior mandible in the context of implant treatment success outcomes.

METHODS

Seven databases, two registries, and reference lists were searched for systematic reviews and meta-analysis (SR/MA), randomized controlled trials (RCTs) and longitudinal studies published in English, Spanish or German since 2012. Confidence in the SR/MA methodology was evaluated using AMSTAR-2 and the risk of bias of primary studies using Cochrane's RoB 2.0 and ROBINS-I. A random-effects meta-analysis and a meta-regression were performed for continuous and dichotomous outcomes. GRADE approach was used to assess the certainty of the evidence.

RESULTS

Eighteen SRs/MAs, most of them "critically low" and "low" confidence with substantial overlap, included 14 relevant RCTs with a high risk of bias. A cohort study with moderate risk of bias was added. Quantitative synthesis of 595 implants and 281 hemiarches/patients indicates that the use of short implants (< 10 mm) compared to regular implants and BA may reduce implant failure at 1-year follow-up, and marginal bone loss (MBL) at 3-, 5-, and 8-year follow-up; is likely to reduce the risk of biological complications at 1-, 3-, 5-, and 8-year follow-up; and may be the patient's preferred alternative. There is a correlation between bone height, MBL and biological complications.

CONCLUSIONS

The available evidence partially suggests that the use of short implants could decrease implant failure, MBL, and biological complications, and increase patient satisfaction. However, given the need for further RCTs and real-world evidence to fully evaluate short- and long-term outcomes, it would be prudent for clinicians to carefully consider the individual needs and circumstances of the patients before deciding whether to use short implants. Trial registration PROSPERO CRD42022333526.

Implant prosthodontic design as a predisposing or precipitating factor for peri-implant disease: A review

Over the past decade, emerging evidence indicates a strong relationship between prosthetic design and peri-implant tissue health. The objective of this narrative review was to evaluate the evidence for the corresponding implant prosthodontic design factors on the risk to peri-implant tissue health. One of the most important factors to achieve an acceptable implant restorative design is the ideal implant position. Malpositioned implants often result in a restorative emergence profile at the implant-abutment junction that can restrict the access for patients to perform adequate oral hygiene. Inadequate cleansability and poor oral hygiene has been reported as a precipitating factors to induce the peri-implant mucositis and peri-implantitis and are influenced by restorative contours. The implant-abutment connection, restorative material selection and restoration design are also reported in the literature as having the potential to influence peri-implant sort tissue health.

Biomechanical finite element analysis of short-implant-supported, 3-unit, fixed CAD/CAM prostheses in the posterior mandible

Objective

To assess the biomechanical effects of different prosthetic/implant configurations and load directions on 3-unit fixed prostheses supported by short dental implants in the posterior mandible using validated 3-D finite element (FE) models.

Methods

Models represented an atrophic mandible, missing the 2nd premolar, 1st and 2nd molars, and rehabilitated with either two short implants (implant length-IL = 8 mm and 4 mm) supporting a 3-unit dental bridge or three short implants (IL = 8 mm, 6 mm and 4 mm) supporting zirconia prosthesis in splinted or single crowns design. Load simulations were performed in ABAQUS (Dassault Systèmes, France) under axial and oblique (30°) force of 100 N to assess the global stiffness and forces within the implant prosthesis. Local stresses within implant/prosthesis system and strain energy density (SED) within surrounding bone were determined and compared between configurations.

Results

The global stiffness was around 1.5 times higher in splinted configurations vs. single crowns, whereby off-axis loading lead to a decrease of 39%. Splinted prostheses exhibited a better stress distribution than single crowns. Local stresses were larger and distributed over a larger area under oblique loads compared to axial load direction. The forces on each implant in the 2-implant-splinted configurations increased by 25% compared to splinted crowns on 3 implants. Loading of un-splinted configurations resulted in increased local SED magnitude.

Conclusion

Splinting of adjacent short implants in posterior mandible by the prosthetic restoration has a profound effect on the magnitude and distribution of the local stress peaks in peri-implant regions. Replacing each missing tooth with an implant is recommended, whenever bone supply and costs permit.