Effect of peri-implant bone resorption on mechanical stress in the implant body: In vivo measured load-based finite element analysis.

BACKGROUND: Research on resolving implant fracture is still gaining attention as it can be a serious treatment failure outcome. The implant fracture is likely to occur due to increased stress in implant body associated with peri-implant bone resorption. OBJECTIVE: This study aimed to investigate the relationship between degree of peri-implant bone resorption and stress distribution in implant body by using finite element analysis (FEA). METHODS: The magnitude and direction of loads on implants at the mandibular molar region were measured with 3D piezoelectric force transducers in a patient during maximal voluntary clenching, grinding and tapping to obtain input for the FEA as the loading condition. Simplified finite element bone models were generated to simulate the six patterns of peri-implant bone resorption progression which the bone levels from implant platform were set at 0, 1, 2, 3, 4 and 5 mm. Three types of implants with different diameters (3.5, 4.0 and 5.0 mm), corresponding abutments and screws were created. FEA using the in vivo measured load was conducted to investigate how peri-implant bone loss affects stress distribution in the implant body. RESULTS: Loading condition affected stress distribution in the implant body. As bone resorption increased, von Mises stress in the implant body became larger, which was marked in smaller diameter implants, and this change was amply demonstrated when the bone resorption increased from 0 to 2 mm. CONCLUSION: The FEA demonstrated that as peri-implant bone loss increased, the magnitude of stress in the implant increased, especially in small diameter implants.

Numerical and experimental study of capillary-driven flow of PCR solution in hybrid hydrophobic microfluidic networks.

Capillary-driven microfluidics is essential for development of point-of-care diagnostic micro-devices. Polymerase chain reaction (PCR)-based micro-devices are widely developed and used in such point-of-care settings. It is imperative to characterize the fluid parameters of PCR solution for designing efficient capillary-driven microfluidic networks. Generally, for numeric modelling, the fluid parameters of PCR solution are approximated to that of water. This procedure leads to inaccurate results, which are discrepant to experimental data. This paper describes mathematical modeling and experimental validation of capillary-driven flow inside Poly-(dimethyl) siloxane (PDMS)-glass hybrid micro-channels. Using experimentally measured PCR fluid parameters, the capillary meniscus displacement in PDMS-glass microfluidic ladder network is simulated using computational fluid dynamic (CFD), and experimentally verified to match with the simulated data.

Clinical indications for radical resection of odontogenic keratocyst: A systematic review.

The aim of this study was to identify clinico pathological indications for radical resection of odontogenic keratocysts (OKCs) in the literature and formulate clinical guidelines for the management of OKCs based on these findings. A systematic review of the literature was undertaken in September 2021 in PubMed/Medline, Scopus, Web of Science, Google Scholar, and Cochrane databases. The following MeSH Keywords terms were used in the search strategies: (odontogenic keratocyst) OR (keratocystic odontogenic tumor) OR (primordial cyst) AND (treatment) OR (Radical resection) OR (Resection of OKC) OR (Treatment methods). Eligibility criteria included publications of clinical studies on histologically confirmed OKCs which underwent radical resection. Studies with less than 5 OKCs, experimental studies, epidemiological studies, studies that included orthokeratinized odontogenic cyst, and review papers were excluded. Ten studies on OKCs reporting on segmental or marginal resections were identified and analyzed qualitatively. Of the total of 221 OKCs that underwent radical resection, 67 OKCs were primary, 30 were recurrent, and the remaining were unclear whether they were primary or recurrent. Segmental mandibulectomy was performed in 131 OKCs, marginal mandibulectomy in 87 OKCs, and 3 OKCs were treated by partial maxillectomy. The main indications for radical resection were multilocular appearance, large OKCs (> 5 cm), multiple recurrent OKCs with or without cortical perforation, and malignant transformation. In conclusion, radical resection has its place in the management of OKC. It is indicated when there is an aggressive lesion with bony perforation, involvement of the pterygoid musculature or skull base, and malignant transformation. The surgeon should aim to identify these features to manage OKC appropriately and to prevent multiple recurrences. Clinical guidelines for the management of OKCs are proposed.

Management of mandibular odontogenic keratocyst through radical resection: Report of 35 cases.

The present study reported the clinical outcomes of 35 patients with mandibular odontogenic keratocysts (OKCs) following treatment by radical resection and immediate defect reconstruction. Amongst 565 patients with OKCs that were treated between April 2003 and May 2015, 35 patients underwent segmental or marginal mandibulectomy. The use of radical resection was based on clinical and/or radiographic evidence of size, cortical perforation and subsequent soft tissue involvement, and on the history of previous recurrence of the same lesion. Recurrence, justifications of the main major factor for resection, and functional and cosmetic results of the patients following mandibular reconstruction were systematically evaluated. There were 26 OKCs in the mandibular molar-ramus region, eight in the mandibular anterior-premolar region and one in the mandibular molar-ramus and anterior-molar regions. Among the 35 patients, 20 had primary OKCs and 15 had recurrent OKCs. A total of 31 patients underwent segmental mandibulectomy, of which 28 were immediately reconstructed with a vascularized flap, whereas four patients underwent marginal mandibulectomy. The functional and cosmetic outcomes of patients were evaluated as satisfactory. The length of the follow-up period ranged from 2 to 17 years following operation (average, 5.82 years). Recurrence was identified in one patient who had been treated with marginal mandibulectomy. In conclusion, the findings from the present study suggested that radical resection may be recommended for patients with OKCs and locally aggressive features. Immediate mandibular reconstruction with a vascularized flap may be a crucial part of this aggressive treatment method that may reduce OKCs-associated morbidity.