Rationale for Mini Dental Implant Treatment

Traumatic Ulceration of the Vestibular Mucous Membrane After Insertion of Four Mini-Implants in the Atrophied Mandible: A Case Report

This clinical report describes how a decubital ulcer arose from the direct contact of the vestibular movable mucous membrane against mini-implant balled-type heads after the mini-implant insertion in the edentulous atrophic mandible of a 78-year-old patient who was not wearing a conventional mandibular complete denture for more than 10 years. Due to severe alveolar ridge atrophy, mini-implant insertion (2.0 mm wide) was an option without extensive surgical procedures. The patient signed the informed consent. A few days after the implant insertion, injury, inflammation, and induration of the vestibular movable mucous membrane were observed on the movable vestibular mucosa on the right side, opposing the mini-implants. The cause of inflammation was attributed to increased perioral muscle tonus which pushed the movable mucosa onto the mini-implant heads and caused mechanical trauma. During the period of edentulism, the perioral muscle tonus increased, directing the mucous membrane of the lips and cheeks against residual ridge to enable food comminution. To treat the persistent decubitus, a bulk of dental composite resin was placed around mini-implant heads and light-cured to protect the mucosa from further mechanical trauma, as the patient did not possess an old mandibular denture to cover the mini-implant heads. Vestibuloplastic surgery (disinsertion of movable attachments and deepening of the vestibulum) was also done. After the surgery, a silicone splint, resembling an occlusal rim, was made to protect the mucous membrane, keep medicaments for faster epitalization in place, to decrease perioral muscle tonus before the new dentures' delivery, and to prevent movable tissue relapse. The custom impression, jaw relationship determination, and try-in of the artificial teeth setup were made with sutures still in place. After the denture delivery and implant loading, the patient was instructed to sleep with the dentures to protect the movable mucous membrane. One year later, almost no peri-implant marginal bone loss was observed, attached and peri-implant mucosa were healthy, and the patient was delighted.

Orofacial esthetics, chewing function, and oral health-related quality of life in Kennedy class I patients with mini-implant-retained removable partial dentures: A 3-year clinical prospective study

This prospective clinical study aimed to assess self-reported orofacial esthetics, chewing function, and oral health-related quality of life (OHRQoL) over three years in the Kennedy Class I patients without posterior dentition who received free-end saddle removable partial dentures (RPDs) retained by two mini dental implants (MDIs) inserted in the canine/first premolar region. The study's robust findings reaffirm the viability of MDI-retained RPDs as a treatment modality in contemporary prosthodontics, instilling confidence in the dental community.

MATERIALS AND METHODS

92 participants with posterior edentulism in the maxilla or mandible received 184 MDIs and 92 RPDs. After one year, three participants were excluded, and another seven were excluded after three years. The final sample was 82 participants. Self-perceived orofacial esthetics was assessed by the Orofacial Esthetic Scale (OES), chewing function by the Chewing Function Questionnaire (CFQ), and the OHRQoL by the OHIP-14. Statistical analysis utilized multivariate regression analysis, standardized effect size calculation, Wilcoxon Signed Rank test, and Friedman's test.

RESULTS

OHRQoL and chewing function significantly improved (p < 0.001) one month after MDI loading by the new RPDs and continued to improve over the observation period (p < 0.05). The OES also significantly improved (p < 0.001) and remained almost unchanged over the next three years (p = 0.440).

CONCLUSION

Despite the limitations of this study, the MDI-retained RPD appears to be a viable treatment modality in contemporary prosthodontics from the patients' perspective.

Clinical Outcomes of Three versus Four Mini-Implants Retaining Mandibular Overdenture: A 5-Year Randomized Clinical Trial

Background and Objectives: Due to a lack of long-term clinical studies that would clarify whether the insertion of three mini-implants (MDIs) can be as successful treatment as the insertion of four MDIs for the retention of mandibular overdentures (ODs), this 5-year prospective cohort study was set up. Materials and Methods: Participants (n = 83) randomly received either four or three MDIs and a mandibular OD. Clinical examinations were performed at the baseline, as well as after one, three, and five years, respectively. A total of 73 participants (38 in the four-MDI and 35 in the three-MDI groups) partook in the study. The marginal bone level change, success and survival rates, and prosthodontic maintenance were assessed. Results: Repeated measures showed that the mean peri-implant bone loss increased progressively at a small amount over five years in both groups (four-MDI group = -0.36 ± 0.74; three-MDI group = -0.33 ± 0.27 mm; p < 0.05). However, an ANCOVA revealed no significant effects of the group (no significant difference between the three- and the four-MDI groups; F = 0.085; p = 0.771), gender (F = 0.023; p = 0.88), or covariate age (F = 1.95; p = 0.167) on the dependent variable: the 5-year MBL change. The success rate (together with successful survival) was 93.8% in the four-MDI group and 91.7% in the three-MDI group. The log-rank (Mantel-Cox) test revealed no significant differences between them (X2 = 0.373; p = 0.541). Conclusions: In patients with narrow ridges, the insertion of three MDIs in the mandible for overdenture retention can be equally as successful as the insertion of four MDIs.

Frailty and mini dental implants

Patients who have been diagnosed as frail and have atrochic jaws may have a dramatic increase of quality of life with mini implant treatment for retention of a mandibular complete denture.

Preoperative Planning Framework for Robot-Assisted Dental Implant Surgery: Finite-Parameter Surrogate Model and Optimization of Instrument Placement

For robot-assisted dental implant surgery, it is necessary to feed the instrument into a specified position to perform surgery. To improve safety and efficiency, a preoperative planning framework, including a finite-parameter surrogate model (FPSM) and an automatic instrument-placement method, is proposed in this paper. This framework is implemented via two-stage optimization. In the first stage, a group of closed curves in polar coordinates is used to represent the oral cavity. By optimizing a finite number of parameters for these curves, the oral structure is simplified to form the FPSM. In the second stage, the FPSM serves as a fast safety estimator with which the target position/orientation of the instrument for the feeding motion is automatically determined through particle swarm optimization (PSO). The optimized feeding target can be used to generate a virtual fixture (VF) to avoid undesired operations and to lower the risk of collision. This proposed framework has the advantages of being safe, fast, and accurate, overcoming the computational burden and insufficient real-time performance of complex 3D models. The framework has been developed and tested, preliminarily verifying its feasibility, efficiency, and effectiveness.

Are Mini Dental Implants Suitable for Support of Crowns or Small Bridges in the Mandibular Incisor Region? A 5-year Longitudinal Study

PURPOSE

It has not been previously studied whether 1-piece category 1 narrow dental implants (≤2.5 mm wide) can successfully support crowns or small bridges. The purpose of this study was to evaluate the long-term benefits of the fixed-type mini dental implants (MDIs) for replacement of mandibular incisors.

MATERIALS AND METHODS

In a prospective cohort study, fixed-type 1-piece MDIs, replacing single or multiple mandibular incisors, supporting metal-ceramic single crowns (unsplinted group), or splinted crowns/small bridges (splinted group) were observed over the period of 5 years. The primary predictor was the splinting status. The primary outcome variables were peri-implant marginal bone level (MBL) change, success, and survival rates (assessed as per Pisa Consensus Conference). The secondary outcomes were dental patient-reported outcome measures (dPROMs) and oral hygiene assessment. Descriptive statistics, Chi-squared test, t-test, Mann-Whitney and Wilcoxon tests, Kaplan-Meier survival analysis, log-rank (Mantel-Cox) comparison, Cox proportional hazard analyses adjusting for number of implants, Spearman correlation, and repeated measures were used for data analysis.

RESULTS

From 44 participants (mean age 56.02 ± 5.72 years), 40 completed the 5-year study: 23 in the splinted and 17 in unsplinted group. Three subjects did not respond, while 1 MDI failed (third year) in the unsplinted group. Mean MBL change in both groups was small; however, it increased over time (-0.22 ± 0.38 mm after 1 year; -0.54 ± 0.56 mm after 5 years; P < .05). After 5 years mean MBL change was -0.59 ± 0.71 mm in the unsplinted and -0.50 ± 0.41 mm in the splinted group (P > .05). Survival analysis revealed no significant difference between the unsplinted (85.7% success, 4.8% failures, and 9.5% satisfactory survivals) and splinted group (93.4% success and 6.6% satisfactory survivals) (P > .05). The group affiliation (unsplinted vs splinted) and number of implants were not significant predictors of MDI failure or survival rates (P > .05). Significant improvement in dPROMs after rehabilitation remained unchanged over 5 years (P > .05). Modified plaque index significantly increased over time, correlating with the MBL loss.

CONCLUSION

MDIs supporting crowns and/or small bridges in the mandibular incisor region showed small rates of marginal bone loss, acceptable success, and survival rates and improved dPROMs over a 5-year observation period.

Stress distribution analysis of novel dental mini-implant designs to support overdenture prosthesis

This study aimed to test and compare two novel dental mini-implant designs to support overdentures with a commercial model, regarding the stress distribution, by photoelastic analysis. Three different mini-implant designs (Ø 2.0 mm × 10 mm) were tested: G1-experimental threaded (design with threads and 3 longitudinal and equidistant self-cutting chamfers), G2-experimental helical (design with 2 long self-cutting chamfers in the helical arrangement), and G3-Intra-Lock® System. After including the mini-implants in a photoelastic resin, they were subjected to a static load of 100 N under two situations: axial and inclined model (30°). The fringe orders (n), that represents the intensity of stresses were analyzed around the mini-implants body and quantified using Tardy's method that calculates the maximum shear stress (τ) value in each point selected. In axial models, less stress was observed in the cervical third mini-implants, mainly in G1 and G2. In inclined models (30°), higher stresses were generated on the opposite side of the load application, mainly in the cervical third of G2 and G3. All mini-implant models presented lower tensions in the cervical third compared with the middle and apical third. The new mini-implants tested (G1 and G2) showed lower stresses than the G3 in the cervical third under axial load, while loading in the inclined model generated greater stresses in the cervical of G2.