Finite element analysis of the biomechanical effects of titanium and Cfr-peek additively manufactured subperiosteal jaw implant (AMSJI) on maxilla

Evaluation of Clinical Success of the 3D-Printed Custom-Made Subperiosteal Implants

OBJECTIVE

The authors aim to share their experiences in subperiosteal implant applications in atrophic jaws, which have been practiced in their clinic for about 2 years, and evaluate the complications and clinical success of the implants.

MATERIAL AND METHOD

Clinical and radiologic data of 32 patients who underwent subperiosteal implantation for advanced alveolar bone loss were evaluated, but 1 patient was excluded as they smoked. Of the 31 patients included in the study, 27 were operated with the diagnosis of total tooth loss, 3 for maxillectomy and 1 for partial tooth loss. A total of 60 subperiosteal implants were placed in them. The mean follow-up period was 15 months.

RESULTS

During the operation, implant-bone adaptation problems were encountered in 11 patients, implant skeletal fracture in 1 patient, and loss of primary stabilization during mini-screw fixation in 2. Although there were no complications in the early postoperative period, biological and prosthetic complications occurred in the late postoperative period. Soft tissue retraction at various levels in 12 patients (only keratinized tissue retraction in 6 and mucosal retraction exceeding keratinized tissue in 6), soft tissue infection in 5 and oroantral fistula development in 1, mini-screw loosening in 3 were the biological complications that occurred.

CONCLUSIONS

Various complications may occur during or after the application of custom-made subperiosteal implants. However, these are manageable and can be reapplied in case of a possible implant loss, making it an important alternative, especially in atrophic jaws where endosseous dental implants cannot be applied.

Biomechanical Fatigue Behavior of a Dental Implant Due to Chewing Forces: A Finite Element Analysis

The use of titanium as a biomaterial for the treatment of dental implants has been successful and has become the most viable and common option. However, in the last three decades, new alternatives have emerged, such as polymers that could replace metallic materials. The aim of this research work is to demonstrate the structural effects caused by the fatigue phenomenon and the comparison with polymeric materials that may be biomechanically viable by reducing the stress shielding effect at the bone-implant interface. A numerical simulation was performed using the finite element method. Variables such as Young's modulus, Poisson's coefficient, density, yield strength, ultimate strength, and the S-N curve were included. Prior to the simulation, a representative digital model of both a dental implant and the bone was developed. A maximum load of 550 N was applied, and the analysis was considered linear, homogeneous, and isotropic. The results obtained allowed us to observe the mechanical behavior of the dental implant by means of displacements and von Mises forces. They also show the critical areas where the implant tends to fail due to fatigue. Finally, this type of non-destructive analysis proves to be versatile, avoids experimentation on people and/or animals, and reduces costs, and the iteration is unlimited in evaluating various structural parameters (geometry, materials, properties, etc.).

Clinical performance of additively manufactured subperiosteal implants: a systematic review

PURPOSE

The aim of this study was to assess implant survival and complications rate of modern subperiosteal implants (CAD designed and additively manufactured).

METHODS

A systematic review was conducted using three electronic databases; Medline (Pubmed), Cochrane library, and SCOPUS, following the PRISMA statement recommendations to answer the PICO question: "In patients with bone atrophy (P), do additively manufactured subperiosteal implants (I), compared to subperiosteal implants manufactured following traditional approaches (c), present satisfactory implant survival and complication rates (O)? The study was pre-registered in PROSPERO (CRD42023424211). Included articles quality was assessed using the "NIH quality assessment tools".

RESULTS

Thirteen articles were finally selected (5 cohort studies and 8 case series), including 227 patients (121 female / 106 male; weighted mean age 62.4 years) and 227 implants. After a weighted mean follow-up time of 21.4 months, 97.8% of implants were in function (5 failures reported), 58 implants (25.6%) presented partial exposure, 12 patients (5.3%) suffered soft tissue or persistent infection. Fracture of the interim prosthesis was reported in 8 of the155 patients (5.2%) in which the use of a provisional prosthesis was reported. A great heterogeneity was found in terms of study design and methodological aspects. For this reason, a quantitative analysis followed by meta-analysis was not possible.

CONCLUSIONS

Within the limitations of this study, modern additively manufactured subperiosteal implants presented a good survival in the short-time, but a noticeable number of soft-tissue related complications were reported. Further studies are needed to assess the clinical behavior in the medium- and long-term.

A 3D dynamic finite element analysis of biomechanical behaviour of maxilla and fixative appliances following advancement Le Fort I surgery applied in different lengths

OBJECTIVES

Dynamic analysis of chewing impact on the stability of rigid fixation techniques following Le Fort I osteotomy has not been investigated in the previous literature. The aim of the present study was to evaluate segmental displacement and von Mises (VM) stress values on the fixation devices following different amounts of Le Fort I advancements under dynamic loading conditions.

MATERIALS AND METHODS

The 3D finite element models simulating 3, 5 and 8 mm advancement of maxilla at the Le Fort I level were generated using CBCT scan data. The models included two anterior L plates and two posterior I plates fixations bilaterally. Dynamic finite element analysis was performed to evaluate their biomechanical behavior against chewing cornflakes bio. Von Mises stresses and displacement values on three points were calculated.

RESULTS

Calculations were made in a time of 38, 40 and 40.5 ms for 3, 5 and 8 mm advancement models, respectively. As the advancement increased, stress values on the plates and displacement values in the D1 (intersection of the apex of the canine tooth with the osteotomy line), D2 (the most prominent point of zygomatic buttress on the osteotomy line), and D3 (intersection of the midline of the second molar tooth with the osteotomy line) points increased. The lowest stress and displacement values were found in the 3 mm advancement model. As advancement increased, the highest values were found in the I plates. The stress levels on the plates and screws remained within safe limits.

CONCLUSIONS

The von Mises stresses and displacement values tend to increase in according with the amount of advancement. More stress is transferred to posterior I plates and screws under dynamic forces.