Tilted implants for the restoration of posterior mandibles with horizontal atrophy: an alternative treatment

Impact of tilted implants for implant-supported fixed partial dentures: A systematic review with meta-analysis

STATEMENT OF PROBLEM

The use of tilted implants has been considered a suitable option for completely edentulous patients. However, consensus on their clinical performance is lacking, specifically for partial rehabilitation.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate the marginal bone loss and implant survival rate of tilted implants compared with those of axial implants for implant-supported fixed partial dentures (ISFPDs).

MATERIAL AND METHODS

A systematic search of the MEDLINE/PubMed, Web of Science, Embase, Cochrane, and ProQuest databases and reference lists for articles published until May 2022 was performed by 2 independent reviewers without language or publication date restrictions. A meta-analysis was performed using the RevMan version 5.4 program. Quality assessments were performed using the Newcastle-Ottawa scale.

RESULTS

Nine studies were included, totaling 258 participants and 604 implants (269 tilted implants and 335 axial implants). No significant differences were found between the tilted and axial implants for the implant survival rate (P=.81; risk ratio: 1.14). However, higher marginal bone loss values were observed for tilted implants (P=.001; mean difference: 0.12 mm). No significant heterogeneity was observed in either analysis.

CONCLUSIONS

No significant relationship was found between tilted and axial implants for ISFPD rehabilitation. However, tilted implants presented greater risks of marginal bone loss than axial implants.

Buccally or Lingually Tilted Implants in the Lateral Atrophic Mandible: A Three-Year Follow-Up Study Focused on Neurosensory Impairment, Soft-Tissue-Related Impaction and Quality of Life Improvement

Background and Objectives: In the severely resorbed posterior mandible, implant placement requires either bone regenerative procedures, subperiosteal implants or short implant placement with drawbacks including morbidity and increased treatment costs and duration. To overcome these inconveniences, some unconventional alternatives have been suggested, such as buccally or lingually tilted implants in the lateral mandible, bypassing the inferior alveolar nerve. The aim of the present retrospective study was to evaluate the three-year survival rate of implants inserted in the posterior atrophic mandible, bypassing the inferior alveolar nerve. The assessment was focused on the occurrence of postoperative complications related to neurosensory impairment and soft tissue impaction, as well as overall improvement in quality of life. Materials and Methods: Patients with severe bone atrophy in the lateral area of the mandible were included in the present study. Only the implants tilted either buccally or lingually to bypass the inferior alveolar nerve were analysed. The relation between peri-implant soft tissue and the healing abutment was assessed and a secondary revision surgery was performed when indicated. The Semmes–Weinstein pressure neurological test was used for qualitative assessment of inferior alveolar nerve function and the Geriatric Oral Health Assessment Index (GOHAI) was used for evaluating Oral-Health-Related Quality of Life (OHRQoL). Results: Fourteen implants were placed in nine patients during the evaluation period. Survival rate was 100%, temporary paraesthesia occurred in one patient and a limited definitive paraesthesia was seen in another patient. Mild or significant discomfort related to soft tissue impaction with healing abutment was observed in six out of nine patients. A statistically significant OHRQoL improvement was observed in all patients. Conclusions: Despite the limited number of patients and observation time, insertion of implants buccally or lingually bypassing the inferior alveolar nerve is a predictive treatment option for patients with severe bone atrophy in the posterior mandible.

Short-term and long-term success and survival rates of implants supporting single-unit and multiunit fixed prostheses: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Whether placing implants to replace each missing tooth or using implant-supported fixed partial dentures provides better outcomes is unclear.

PURPOSE

The purpose of this systematic review and meta-analysis was to assess the success and survival rates of implants supporting single-unit and multiunit fixed prostheses by using conventional protocols for placement and loading in short- and long-term follow-ups.

MATERIAL AND METHODS

An electronic search was conducted in PubMed, Scopus, and Web of Science for studies published up to March 17, 2022. Comparative studies that reported the success or survival rates of both single-unit and splinted multiunit prostheses were considered for qualitative and quantitative analyses.

RESULTS

A total of 68 publications comprising 11 271 implants were included. Compared with the single prostheses, the splinted multiunit group showed no significant differences in implant success rates in the short-term (risk difference=-0.004; 95% confidence interval (CI)=-0.033 to 0.025; P=.780) and long-term (risk difference=0.003; 95% confidence interval (CI)=-0.029 to 0.034; P=.874) follow-ups. Significant statistical differences were also not found in terms of the survival rates of the 2 groups (short-term risk difference=-0.004; 95% CI=-0.031 to 0.023; P=.779, long-term risk difference=-0.002; 95% CI=-0.029 to 0.025; P=.887).

CONCLUSIONS

Implants supporting single-unit or splinted multiunit prostheses seem to be a predictable treatment in terms of survival and success over short and long periods. Nonetheless, it seems that cantilever and nonsplinted multiunit prostheses should be used with more caution.

Volumetric Evaluations of Full-Arch Implant Supported Restorations and Their Role on Patients’ Quality of Life: A Mixed-Model Analysis

Introduction

Full-arch, implant-supported hybrid restorations, employing tilted implants, can offer an efficient way of treating edentulous patients. Several factors, such as the timing of implant placement and the inclination of the fixture, can have a detrimental effect on their stability. This retrospective study is aimed at discerning the role played by those factors.

Materials and Methods

Patients treated with full-arch, implant supported restorations were selected for this study; cone-beam computed tomography (CBCT) images, taken 3 months and 3 years after delivery of the final restoration, as well as peri-implant values, were obtained and compared; bone loss was measured on four sites for each implant and then averaged. These patients were recalled, and the OHIP-5 questionnaire was administered.

Results

21 patients, with a mean age of 53 years, were included in the present analysis. 108 implants were placed, and 25 Toronto prostheses were delivered. According to a mixed-model analysis, tilted implants (0.51, p < 0.001) had a higher rate of bone loss, while implants placed in a healed ridge suffered less bone loss than immediate implants (-0.21, p < 0.001). Patient-level variables have a significant effect on this variable, as implants coming from the same subject share a similar risk of bone loss. The mean response to the self-administered OHIP-5 questionnaire was 1.53 ± 0.29; other variables did not have a statistically significant effect on this outcome. Discussion/Conclusions. The results of the present study show that Toronto bridges prostheses are an efficient procedure for treating edentulous patients, as their oral-related quality of life is reported as satisfactory even 7 years after delivery of the restoration. Tilted and immediate implants are more at risk of bone loss. Implants coming from the same subject share a similar risk of bone loss.

Effect of Splinting of Tilted External Hexagon Implants on 3-Unit Implant-Supported Prostheses in the Posterior Maxilla: A 3D Finite Element Analysis

PURPOSE

To assess the effects of tilted external hexagon implants and splinted restorations in terms of stress distribution on the bone tissue, implants, and prosthetic screws, using three-dimensional finite element analysis.

MATERIALS AND METHODS

Six models were used to simulate a posterior maxilla bone block (type IV) from the first premolar to the first molar. Each model included three 4.1-mm-diameter external hexagon implants with varying inclinations (0°, 17°, and 30°) and crown designs (splinted and nonsplinted restorations). The forces applied were as follows: 400 N axially (50 N for each slope of the cusp) and 200 N obliquely (45° only on the buccal slope of the cusp). Stress distribution on the implants and prosthetic screw was evaluated using Von Mises stress, while the maximum principal stress was used to evaluate the stress distribution in the bone tissue.

RESULTS

The oblique load increased the stress on all the structures in all the models. Increased inclination of the implants resulted in higher stress concentration in the bone tissue, implants, and prosthetic screws. However, splinted restorations contributed to reduction of the stress for the oblique loading, mainly in the bone tissue and prosthetic screw of the first molar, as the stress was shared between the first and second premolar restorations.

CONCLUSIONS

Tilted implants increased proportionally the stress on bone tissue and prosthetic screws of models. Additionally, splinting restorations reduced the stress concentration area in the simulated bone tissue, implants, and prosthetic screws in the first molar, as the stress was shared with the adjacent implants.

Influence of soft tissue grafting, orofacial implant position, and angulation on facial hard and soft tissue thickness at immediately inserted and provisionalized implants in the anterior maxilla

BACKGROUND

Resorption of hard and soft tissues following immediate implant insertion is frequently reported. Data regarding the influencing factors on facial tissue thickness are rare.

PURPOSE

This retrospective study investigated the impact of connective tissue grafting, the orofacial angulation and position of immediately inserted and provisionalized implants on the facial hard and soft tissue thickness in the anterior maxilla within a 1- to 5-year follow-up.

MATERIAL AND METHODS

Implants with the prerequisite of having preoperative and postoperative cone beam computed tomography (CBCT) and a follow-up of 1 to 5 years were included. Facial bone deficiencies were grafted flaplessly with autogenous bone in all sites. In a subgroup of implants additional connective tissue grafting was performed, whereas the remaining implants were not grafted with soft tissue. The orofacial tooth and implant angulation, the change of horizontal position and the facial bone thickness were measured by CBCT, the facial mucosa thickness by an ultrasonic device.

RESULTS

In total, 76 implants were placed in 55 patients. Sixty-nine sites showed a facial bone defect. Thirty-eight received a connective tissue graft additionally. All implants were still in function after a mean follow-up of 36 months. The mean thickness of the facial mucosa was 1.72 mm at 1 mm, 1.63 mm at 4 mm, 1.52 mm at 6 mm, and 1.66 mm at 9 mm apically to mucosal margin. The bone thickness was 0.02, 0.25, and 0.36 mm initially and 1.32, 1.26, and 1.11 mm finally at 1, 3, and 6 mm apically to implant shoulder level. Mixed model analysis revealed an impact of the preoperative bone status on the facial bone increase. The facial soft tissue thickness was significantly influenced by the gingival biotype.

CONCLUSIONS

The results indicate that an initial severe hard tissue defect allows for significant bone regeneration. The facial soft tissue thickness is primarily influenced by the gingival biotype.

Does increasing the number of short implants reduce marginal bone loss in the posterior mandible? A prospective study

Marginal bone loss is a concern in the long-term prognosis of short dental implants. The aim of this prospective cohort study was to evaluate the loss when variable numbers of short implants were used in the posterior mandible. The subjects were allocated into three groups according to the number of short implants. The first group was given two, the second three, and the third four. Each patient had radiographs taken immediately after loading and repeated 36 months later. Twenty- three subjects with 65 implants were entered in the three groups. The mean (SD) marginal bone loss was 0.49 (0.04) mm in the two implant group, 0.41 (0.25) mm in the three implant group, and 0.35 (0.25) mm in the four implant group. There were significant differences in marginal bone loss among the three groups (p=0.001), in that the fewer the number of short implant-supported fixed prostheses in the posterior mandible, the greater the marginal bone loss. When we used more short implants the amount of marginal bone loss decreased.

Angulated implants: an alternative to bone augmentation and sinus lift procedure: systematic review

Rehabilitation of completely edentulous patients with implant becomes challenging due to reduced amount of bone available and pneumatisation of maxillary sinus or both. To successfully treat such patients, prior to implant placement, patient has to undergo invasive procedures like sinus lift and/or bone augmentation which is not possible many time due to many reasons. This article focuses on an alternative treatment procedure in which two posterior implants are placed at an angle and two anterior implants are placed axially thereby eliminating the need for sinus lift or bone augmentation procedures. This article broadly discusses this "All on Four" concept in all aspects, its effects on bone, prosthesis survival, forces acting etc along with various related studies.

Posterior partially edentulous jaws, planning a rehabilitation with dental implants

AIM: To discuss important characteristics of the use of dental implants in posterior quadrants and the rehabilitation planning.

METHODS: An electronic search of English articles was conducted on MEDLINE (PubMed) from 1990 up to the period of March 2014. The key terms were dental implants and posterior jaws, dental implants/treatment planning and posterior maxilla, and dental implants/treatment planning and posterior mandible. No exclusion criteria were used for the initial search. Clinical trials, randomized and non randomized studies, classical and comparative studies, multicenter studies, in vitro and in vivo studies, case reports, longitudinal studies and reviews of the literature were included in this review.

RESULTS: One hundred and fifty-two articles met the inclusion criteria of treatment planning of dental implants in posterior jaw and were read in their entirety. The selected articles were categorized with respect to their context on space for restoration, anatomic considerations (bone quantity and density), radiographic techniques, implant selection (number, position, diameter and surface), tilted and pterygoid implants, short implants, occlusal considerations, and success rates of implants placed in the posterior region. The results derived from the review process were described under several different topic headings to give readers a clear overview of the literature. In general, it was observed that the use of dental implants in posterior region requires a careful treatment plan. It is important that the practitioner has knowledge about the theme to evaluate the treatment parameters.

CONCLUSION: The use of implants to restore the posterior arch presents many challenges and requires a detailed treatment planning.