Mandible Biomechanics and Continuously Erupting Teeth: A New Defect Model for Studying Load-Bearing Biomaterials

Animals with elodont dentition and unfused mandible symphyses are hypothesized to have symmetric incisor morphology. Since these animals maintain their teeth by gnawing, they may provide physiologic feedback on mechanical function when unilateral mandible defects are created that manifest as ipsilateral changes in tooth structure. This defect model would potentially generate important information on the functional/mechanical properties of implants. Rats’ and rabbits’ mandibles and teeth are analyzed with µCT at baseline and post-intervention (n = 8 for each). Baseline incisors were compared. In a unilateral mandible pilot study, defects—ranging from critical size defect to complete ramus osteotomies—were created to assess effect on dentition (rats, n = 7; rabbits, n = 6). Within 90% confidence intervals, animals showed no baseline left/right differences in their incisors. There are apparent dental changes associated with unilateral defect type and location. Thus, at baseline, animals exhibit statistically significant incisor symmetry and there is an apparent relationship between mandible defect and incisor growth. The baseline symmetry proven here sets the stage to study the degree to which hemi-mandible destabilizing procedures result in measurable & reproducible disruption of dental asymmetry. In a validated model, an implant designed to function under load that prevents incisor asymmetry would provide supporting evidence that the implant has clinically useful load-bearing function.

Reconstruction of mandible defect with folded free fibular flap

Mandibular defects directly affect a patient’ facial features, masticatory and articulation. This study has analyzed 41 patients with mandibular ameloblastoma who underwent a partial mandibulectomy and reconstruction by folding the free fibular flap. In the preoperative and postoperative (6 months and 24 months after surgery), the QOL of these patients was assessed by using the University of Washington Quality of Life Questionnaire (UW-QOL) and the medical outcome study short form-36 (SF-36) questionnaires. The sf-36 survey showed that body pain, general health, and health changes decreased significantly at 6 months after surgery, but the mean score at 24 months after surgery all exceeded that shown before surgery. The UW-QOL survey showed that chewing, speech and taste had significantly changed in the 6 months after the surgery, and the difference was statistically significant 24 months after the surgery. The total score of the patients almost recovered to the preoperative level at 24 months after the surgery. The folded free fibular flap is an ideal selection for the reconstruction of oral defects after cancer resection. In using this flap, the basic social need of patients after surgery can be satisfied. The folded free fibular flap can improve the patients’ QOL.

Morphological Characteristics of the Osteoplastic Potential of Synthetic CaSiO3/HAp Powder Biocomposite

The study describes the influence of synthetic CaSiO3/HAp powder biocomposite on the process of regeneration in osseous tissue in the alveolar ridges in terms of the morphological characteristics of the osteoplastic potential. The authors investigated the osteoinduction and osteoconduction “in vivo” processes during bone tissue regeneration in the mandible defect area of an experimental animal (rabbit). The possibility of angiogenesis in the graft as an adaptation factor was studied in the process of bone tissue regeneration. The results of the histological study that included the qualitative parameters of bone tissue regeneration, the morphometric parameters (microarchitectonics) of the bone, the parameters of osteosynthesis (thickness of the osteoid plates), and resorption (volume density of the eroded surface) were presented. The results allowed the authors to characterize the possibility of the practical adaptation for synthetic powder biocomposite as an osteoplastic graft for the rehabilitation of osseous defects in dentistry.

Morphological assessment of osseointegration during replacement of mandible defect with implants that made using additive technologies. Experimental research

According to the pre-made patterns of 3D-design and prototyping patterns during the experiment, defects of the lateral portion of the ram's lower jaw were created using the piezosurgical technique. The defects were replaced by plastic implants obtained by the method of layer-by-layer melting of FDM-printing (fusing deposition modeling, FDM) and fixing titanium screws to the jaw body. In the time interval, plastic implants are replaced by titanium ones, obtained using SLS technology -selective laser sintering using a 3D-printer. In order to study the processes of reparative osteogenesis, microsamples of tissues of the periimplantation zone were analyzed. As a result, signs of osteo- and fibro-osseointegration were identified. The data obtained are regarded as a prerequisite for further clinical trials of the developed protocols for the sequential replacement of defects of the jaws using 3D-printing.