Predictability of short implants ( < 10 mm) as a treatment option for the rehabilitation of atrophic maxillae. A systematic review

How far can we go? A 20-year meta-analysis of dental implant survival rates

OBJECTIVE

This meta-analysis aims to investigate the long-term survival rates of dental implants over a 20-year period, providing a practical guide for clinicians while identifying potential areas for future research.

MATERIALS AND METHODS

Data were sourced from recent publications, focusing exclusively on screw-shaped titanium implants with a rough surface. Both retrospective and prospective studies were included to ensure an adequate sample size. A systematic electronic literature search was conducted in the databases: MEDLINE (PubMed), Cochrane, and Web of Science. The risk of bias for all studies was analyzed using a tool by Hoy et al. RESULTS: Three prospective studies (n = 237 implants) revealed a mean implant survival rate of 92% (95% CI: 82% to 97%), decreasing to 78% (95% CI: 74%-82%) after imputation (n = 422 implants). A total of five retrospective studies (n = 1440 implants) showed a survival rate of 88% (95% CI: 78%-94%). Implant failure causes were multifactorial.

CONCLUSION

This review consolidates 20-year dental implant survival data, reflecting a remarkable 4 out of 5 implants success rate. It emphasizes the need for long-term follow-up care, addressing multifactorial implant failure. Prioritizing quality standards is crucial to prevent overestimating treatment effectiveness due to potential statistical errors. While dental implantology boasts reliable therapies, there is still room for improvement, and additional high-quality studies are needed, particularly to evaluate implant success.

CLINICAL RELEVANCE

Never before have the implant survival over 20 years been systematically analyzed in a meta-analysis. Although a long-term survival can be expected, follow-up is essential and shouldn't end after insertion or even after 10 years.

Survival of conventional dental implants in the edentulous atrophic maxilla in combination with zygomatic implants: a 20-year retrospective study

PURPOSE

Implant-supported prosthetic rehabilitation in the resorbed maxilla is a great challenge. The aim of this study was to determine the survival rate of conventional anterior implants placed in combination with zygomatic implants according to the Brånemark technique, and to identify risk factors for implant failure.

METHODS

We collected data retrospectively from 72 consecutive patients who received treatment from 1998 to 2018 at our center, according to Brånemark's original technique. Kaplan-Meier analysis was conducted to assess survival rate, and a survival regression model was used with the patient as the random factor, applying the Weibull distribution.

RESULTS

A total of 236 maxillary anterior implants were included, with a mean follow-up of 12.1 years. Kaplan-Meier analysis showed overall cumulative survival rates of 95.3% at 1 year, 94.8% at 2 years, 93.0% at 5 years, 90.5% at 10 years, 81.6% at 15 years, and 67.7% at 20 years. Survival regression showed an association between bruxism and implant failure as well as implants bearing an overdenture. Implants with length ≤ 10 mm had a significantly lower survival time. No significant association was found between the number of anterior implants and survival rate.

CONCLUSIONS

We found acceptable long-term anterior conventional implant survival. Significant risk factors for failure were bruxism, overdentures, and implants shorter than 10 mm.

Short versus Longer Implants in Sites without the Need for Bone Augmentation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

The present systematic review and meta-analysis aims to analyse the clinical performance of short compared to longer implants inserted in sites without the need for bone augmentation.

METHODS

The protocol of the present PRISMA-driven meta-analysis was registered on PROSPERO (CRD42021264781). Electronic and manual searches were performed up to January 2022. All Randomized Controlled Trials (RCTs) comparing short (≤6 mm) to longer (≥8.5 mm) implants placed in non-atrophic and non-augmented sites were included. The quality of the included studies was assessed using the Cochrane risk of bias tool for randomized clinical trials (RoB 2) and the quality of evidence was determined with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. A meta-analysis was performed on implant survival rate, marginal bone level change (MBLc), and technical and biological complications at the available follow-up time points. The power of the meta-analytic findings was determined by trial sequential analysis (TSA).

RESULTS

From 1485 initial records, 13 articles were finally included. No significant difference was found in the survival rate between short and long implant at any follow-up (moderate quality of evidence). Significantly more bone loss for long implants at 1 and 5 years from implant placement and more technical complications with short implants at 10 years were found. No other significant inter-group differences in terms of MBLc and biological complications were detected.

CONCLUSIONS

Moderate evidence exists suggesting that short implants perform as well as longer ones in the rehabilitation of edentulous sites without the need for bone augmentation. Further long-term, well-designed RCTs, however, are still needed to provide specific evidence-based clinical recommendations for an extended use of short implants in non-atrophic sites.

1-Year Post-loading of Short and Ultrashort Implants in Posterior Mandibular and Maxillary Regions

BACKGROUND: Short implants have been proposed as an option for management of deficient alveolar ridges without the need for complex augmentation procedures. AIM: In this study, we aim to assess the use of short and ultrashort implants for the management of deficient alveolar ridges in posterior mandibular and maxillary areas with a 1-year post-loading follow-up. METHODOLOGY: Ten patients were recruited in this trial with a total of 14 implants to be placed. The patients all needed implants in the maxillary/mandibular posterior regions for prosthetic rehabilitation with deficient alveolar ridge heights. Implants of 5 mm diameter and lengths either 6 or 8.5 mm were to be placed in the edentulous spaces after proper radiographic assessment. Two-stage surgeries were followed with ¾ months between implant placement and loading. The follow-up lasted for a year to allow for peri-implant clinical assessment and radiographic analysis. RESULTS: All patients showed uneventful healing and no infection, wound dehiscence or inflammation was noted. Prosthetic rehabilitation was successful and satisfactory to the patients. None of the cases showed excessive marginal bone loss and stability was maintained at acceptable levels to the end of the follow-up period. CONCLUSION: Within the limitations of this study, short and ultrashort implants seem like a valid option for management of posterior edentulous regions with deficient ridge heights.

Ultrashort Implants, Alternative Prosthetic Rehabilitation in Mandibular Atrophies in Fragile Subjects: A Retrospective Study

This study aimed to evaluate the effectiveness of using ultrashort implants in the rehabilitation of jaws of fragile patients. The aim of the study was to retrospectively evaluate the survival rate of full-arch prosthetic rehabilitation on ultrashort implants, length 4 mm, 4 mm in diameter in the premolar and canine area and 4.5 mm in diameter in the molar area, with the insertion torque of 60 Nw and immediate loading. Nineteen patients were evaluated for 3 years clinically and radiographically. The significant majority of the patients at the 3 year follow-up (T4) presented a stable and functional implant-supported prothesis, and the survival rate of the implants was 85%, with a loss of 16 implants on 114 implants. The combination of the innovative implant surfaces and the correct project of the prostheses, with the related implant connection, determined a different timing in the therapy, allowing to obtain an immediate loading, which is currently demanded by patients. This and recent reports on short and ultrashort implant usage in atrophic jaws offer a good solution in critical cases. In conclusion, within the limits of the study, the full-arch rehabilitation with immediate loading on ultrashort implants showed good results with few postoperative complications and related low biological cost.

A Minimally Invasive Technique for Short Spiral Implant Insertion with Contextual Crestal Sinus Lifting in the Atrophic Maxilla: A Preliminary Report

The most recently reported techniques for the rehabilitation of the atrophic posterior maxilla are increasingly less invasive, as they are generally oriented to avoid sinus floor elevation with lateral access. The authors describe a mini-invasive surgical technique for short spiral implant insertion for the prosthetic rehabilitation of the atrophic posterior maxilla, which could be considered a combination of several previously described techniques based on the under-preparation of the implant site to improve fixture primary stability and crestal approach to the sinus floor elevation without heterologous bone graft. Eighty short spiral implants were inserted in the molar area of the maxilla in patients with 4.5–6 mm of alveolar bone, measured on pre-operative computed tomography. The surgical technique involved careful drilling for the preparation of implant sites at differentiated depths, allowing bone dislocation in the apical direction, traumatic crestal sinus membrane elevation, and insertion of an implant (with spiral morphology) longer than pre-operative measurements. Prostheses were all single crowns. In all cases, a spiral implant 2–4 mm longer than the residual bone was placed. Only two implants were lost due to peri-implantitis but subsequently replaced and followed-up. Bone loss values around the implants after three months (at the re-opening) ranged from 0 to 0.6 mm, (median value: 0.1 mm), while after two years, the same values ranged from 0.4 to 1.3 mm (median value: 0.7 mm). Clinical post-operative complications did not occur. After ten years, no implant has been lost. Overall, the described protocol seems to show good results in terms of predictability and patient compliance.

Comparative Analysis of Peri-Implant Bone Loss in Extra-Short, Short, and Conventional Implants. A 3-Year Retrospective Study

Objective: To evaluate the influence of implant length on marginal bone loss, comparing implants of 4 mm, 6 mm, and >8 mm, supporting two splinted crowns after 36-month functional loading. Materials and Methods: this retrospective clinical trial evaluated the peri-implant behavior of splinted crowns (two per case) on pairs of implants of the same length placed in the posterior maxilla (molar area). Implants were divided into three groups according to length (Group 1: extra-short 4 mm; Group 2: short 6 mm; Group 3: conventional length >8 mm). Marginal bone loss was analyzed using standardized periapical radiographs at the time of loading and 36 months later. Results: 24 patients (19 women and 5 men) were divided into three groups, eight rehabilitations per group, in the position of the maxillary first and second molars. The 48 Straumann^® Standard Plus (Regular Neck (RN)/Wide Neck (WN)) implants were examined after 36 months of functional loading. Statistical analysis found no significant differences in bone loss between the three groups (p = 0.421). No implant suffered biological complications or implant loss. Long implants were associated with less radiographic bone loss. Conclusions: extra-short (4 mm); short (6 mm); and conventional length (>8 mm) implants in the posterior maxilla present similar peri-implant bone loss and 100% survival rates in rehabilitation, by means of two splinted crowns after 36 months of functional loading. Implants placed in posterior positions present better bone loss results than implants placed in anterior positions, regardless of the interproximal area where bone loss is measured. Conventional length (>8 mm) implants show better behavior in terms of distal bone loss than short (6 mm) and extra-short (4 mm) implants.

Dental Implants

Systematic reviews of literature over the period between 2008 and 2017 are discussed regarding clinical evidence for the factors affecting survival and failure of dental implants. The factors addressed include publication bias, tooth location, insertion torque, collar design, implant-abutment connection design, implant length, implant width, bone augmentation, platform switching, surface roughness, implant coatings, and the use of ceramic materials in the implant body and abutment.

Clinical and Radiographic Evaluation of Short Implants Placed in the Posterior Mandible: A 1-Year Pilot Split-Mouth Study

In many cases, due to anatomical limitations, the placement of regular-length implants cannot be facilitated without the performance of advanced surgical procedures. However, these are associated with morbidity, prolonged treatment time, and costs. To overcome such disadvantages, short implants were introduced. The aim of this prospective pilot split-mouth study was to compare the clinical outcome between short implants (7 mm) and regular-length (≥10 mm) implants placed in the posterior mandible after 1 year of prosthetic delivery. Ten patients received 4 implants in the posterior mandible. Two short implants were placed in one side and 2 regular-length implants were placed contralaterally. These were restored by means of splinted screw-retained metal-ceramic crowns. Marginal bone loss (MBL) and soft-tissue parameters were compared. No implant failed. Both types of implants showed success rates of 90% and survival rates of 100%. From prosthetic delivery to 1 year post-loading a bone gain of +0.29 mm for short implants and +0.19 mm for regular-length implants was present without showing any statistically significant differences in MBL between the 2 implant types ( P > .05). Bleeding on probing, clinical attachment level, probing depth, and crown-to-implant ratio did not show any statistically significant differences between the 2 implant lengths ( P > .05). One case of chipping occurred in the regular-length implant group, leading to a prosthetic survival rate of 95%. Short implants showed a prosthetic survival rate of 100%. After 1 year, short implants showed comparable clinical outcomes to that of regular-length implants, making them a viable treatment option in the posterior mandible.