Investigation of the biomechanical stability of Cfr-PEEK in the treatment of mandibular angulus fractures by finite element analysis

Jawline improvement using patient-specific angle implants with virtual planning in orthognathic surgery

There has been a recent increase in the global demand for jawline augmentation. Managing angle definition in patients undergoing orthognathic surgery remains challenging owing to the characteristics of classic mandibular osteotomy, which mostly allows sagittal mandibular movements but cannot modify the ramus height. The advent of computer-assisted surgical planning and computer-aided design/computer-aided manufacturing techniques for patient-specific implant fabrication has introduced new methods for jawline management. In this study, we aimed to assess jawline improvement using patient-specific angle implants in 18 patients undergoing orthognathic surgery with standard osteotomies. Since jawline's shape is an aesthetic refinement of orthognathic surgery, it has to be assessed with the inclusion of the soft tissues. Therefore, this study focused on jawline improvement by comparing the preoperative and postoperative 3D-photographs of each patient's face using the VECTRA H2 Imaging System camera device and software. Quantitative analysis revealed that the mean volumetric angle expansion was 4.6 mm (males, 4.71 mm; females, 4.48 mm). Qualitative and quantitative analyses revealed that the jaw angle parameters were concordant with the ideal female and male jaw angle parameters proposed in the literature. Patient-specific titanium angle implants are a promising and safe method for jawline improvement in patients undergoing orthognathic surgery.

Biomechanical comparison of the efficacy of Cfr-PEEK and titanium systems in the fixation following sagittal split advancement osteotomy: a biomechanical study

BACKGROUND

This study evaluates the efficacy of carbon fiber reinforced Polyetheretherketone (Cfr-PEEK) in fixation after sagittal split ramus osteotomy (SSRO) by comparing it with titanium in vitro.

METHODS

Twenty-eight sheep hemimandibles were randomly assigned to four groups for SSRO surgery. Fixation was performed with a 4-hole titanium mini plate for 5 mm advancement in Group 1, with a 4-hole Cfr-PEEK mini plate for 5 mm advancement for Group 2, with a 4-hole titanium mini plate for 10 mm advancement for Group 3, and with a 4-hole Cfr-PEEK mini plate for 10 mm advancement for Group 4. A linear vertical load of 50 N was applied to all models from the molar region. Displacement values were recorded digitally.

RESULTS

There was a significant difference among the displacement values of four groups (p < 0.05). The highest displacement values were observed in group 2 and the lowest in group 3. The Cfr-PEEK plates' fixed groups showed lower displacement values than their titanium counterparts.

CONCLUSIONS

According to this study, Cfr-PEEK provides better stability than titanium by considering the displacement values. However, future experimental and clinical studies that include larger samples and different designs need to be done.

PEEK for Oral Applications: Recent Advances in Mechanical and Adhesive Properties

Polyetheretherketone (PEEK) is a thermoplastic material widely used in engineering applications due to its good biomechanical properties and high temperature stability. Compared to traditional metal and ceramic dental materials, PEEK dental implants exhibit less stress shielding, thus better matching the mechanical properties of bone. As a promising medical material, PEEK can be used as implant abutments, removable and fixed prostheses, and maxillofacial prostheses. It can be blended with materials such as fibers and ceramics to improve its mechanical strength for better clinical dental applications. Compared to conventional pressed and CAD/CAM milling fabrication, 3D-printed PEEK exhibits excellent flexural and tensile strength and parameters such as printing temperature and speed can affect its mechanical properties. However, the bioinert nature of PEEK can make adhesive bonding difficult. The bond strength can be improved by roughening or introducing functional groups on the PEEK surface by sandblasting, acid etching, plasma treatment, laser treatment, and adhesive systems. This paper provides a comprehensive overview of the research progress on the mechanical properties of PEEK for dental applications in the context of specific applications, composites, and their preparation processes. In addition, the research on the adhesive properties of PEEK over the past few years is highlighted. Thus, this review aims to build a conceptual and practical toolkit for the study of the mechanical and adhesive properties of PEEK materials. More importantly, it provides a rationale and a general new basis for the application of PEEK in the dental field.

Accuracy of Segmented Le Fort I Osteotomy with Virtual Planning in Orthognathic Surgery Using Patient-Specific Implants: A Case Series

Background: When maxillary transversal expansion is needed, two protocols of treatment can be used: a maxillary orthodontic expansion followed by a classical bimaxillary osteotomy or a bimaxillary osteotomy with maxillary segmentation. The aim of this study was to assess the accuracy of segmented Le Fort I osteotomy using computer-aided orthognathic surgery and patient-specific titanium plates in patients who underwent a bimaxillary osteotomy for occlusal trouble with maxillary transversal insufficiencies. Methods: A virtual simulation of a Le Fort I osteotomy with maxillary segmentation, a sagittal split ramus osteotomy, and genioplasty (if needed) was conducted on a preoperative three-dimensional (3D) model of each patient’s skull using ProPlan CMF 3.0 software (Materialise, Leuven, Belgium). Computer-assisted osteotomy saw-and-drill guides and patient-specific implants (PSIs, titanium plates) were produced and used during the surgery. We chose to focus on the maxillary repositioning accuracy by comparing the preoperative virtual surgical planning and the postoperative 3D outcome skulls using surface superimpositions and 13 standard dental and bone landmarks. Errors between these preoperative and postoperative landmarks were calculated and compared to discover if segmental maxillary repositioning using PSIs was accurate enough to be safely used to treat transversal insufficiencies. Results: A total of 22 consecutive patients—15 females and 7 males, with a mean age of 27.4 years—who underwent bimaxillary computer-assisted orthognathic surgery with maxillary segmentation were enrolled in the study. All patients presented with occlusion trouble, 13 with Class III malocclusions (59%) and 9 (41%) with Class II malocclusions. A quantitative analysis revealed that, overall, the mean absolute discrepancies for the x-axis (transversal dimension), y-axis (anterior−posterior dimensions), and z-axis (vertical dimension) were 0.59 mm, 0.74 mm, and 0.56 mm, respectively. The total error rate of maxillary repositioning was 0.62 mm between the postoperative cone-beam computed tomography (CBCT) and the preoperatively planned 3D skull. According to the literature, precision in maxilla repositioning is defined by an error rate (clinically relevant) at each landmark of <2 mm and a total error of <2 mm for each patient. Conclusions: A high degree of accuracy between the virtual plan and the postoperative result was observed.

Biomechanical performance of Ti-PEEK dental implants in bone: An in-silico analysis

Stress-shielding is caused by a significant mismatch in stiffness between bone tissue and Ti alloy dental implants. Therefore, in this study, a Ti-PEEK composite implant was examined and compared with conventional titanium, to determine the behavior of the host bone. Twelve 3D finite element models were modeled with two conditions of marginal cortical bone (with and without marginal bone loss). Six implant designs were constructed. Implant (A) was made with a conventional design (dense titanium), implants (B), (C) and (D) are designed with Ti-PEEK composite (outer layer made of PEEK and inner structures made of Ti with hexagonal, cylindrical, and cross shapes for implants (B), (C) and (D), respectively), the implant (E) is designed with Ti at the upper half section and PEEK at the bottom half section, and the implant (F) is designed with PEEK at the upper half section and Ti at the bottom half section. An axial load of 200 N was applied to the buccal cusp and central fossa of the occlusal surface. The displacements, stress, and equivalent strain were analyzed at the level of bone tissue. The mechanostat of Frost was used to determine the behavior of the cancellous bone under these biomechanical conditions. Results showed that strains were greater in cancellous bone with marginal bone loss than in healthy bone (w/o MBL). When compared to implants (B)-(F), conventional implant (A) did not produce as much strain. Thus, results and analyses suggest that the Ti-PEEK implants outperform compared with the implant (A) in the case of no marginal bone loss. However, the implants (A) and (E) perform equally in terms of bone loss.