Orthognathic Surgery of the Mandible.

Orthognathic surgery performed in conjunction with orthodontic treatment is commonly performed to correct skeletal irregularities and realign the maxillomandibular relationship to improve occlusal function and facial esthetics. A thorough understanding of soft tissue esthetics, skeletal and occlusal relationships, and surgical techniques is required to obtain successful results. Surgical techniques have evolved greatly throughout history, as technological advances such as virtual surgical planning have become available and widely used to obtain predictable movements with minimized complications. The aim of this article is to review the orthognathic surgical procedures of the mandible, with particular attention to the indications, contraindications, preoperative assessment, surgical technique, and possible complications encountered.

Orthognathic Surgery-LeFort I Osteotomy.

Orthognathic surgery is a complex type of facial surgery that can have a profound impact on a patient's occlusal function and facial aesthetics. Close collaboration between the maxillofacial surgeon and an orthodontist is required, and the surgical team must have a strong foundation in facial analysis and firm understanding of the maxillofacial skeleton to achieve surgical success. Herein, we review the maxillary LeFort I osteotomy as it pertains to orthognathic surgery, with particular attention to the indications, contraindications, preoperative assessment, surgical technique, and possible complications encountered.

Chondroitin sulfate is involved in the hypercalcification of the organic matrix of bovine peritubular dentin.

Apatitic mineral of dentin forms within the collagenous matrix (intertubular dentin, ITD) secreted from the odontoblastic processes (OP). Highly calcified mineral (peritubular dentin, PTD) is deposited at the interface between the ITD and each process membrane, creating a tubular system penetrating the dentin that extends from the dentino-enamel junction to the predentin-dentin junction. We focus on determining the composition of the PTD both with regard to its organic matrix and the inorganic phase. A laser capture technique has been adapted for the isolation of the mineralized PTD free from the ITD, and for the analysis of the PTD by SEM, TEM, and energy dispersive spectrometry (EDS), these data were subsequently compared with similar analyses of intact dentin slices containing ITD bounded-PTD annuli. Elemental line scans reveal clearly marked boundaries between ITD, PTD, and OP components, and illustrate the differences in composition, and topographical surface roughness. The organic matrix of the PTD was shown to be sulfur rich, and further antibody labeling showed the sulfated organic component to be chondroitin sulfate [corrected]. In this PTD organic matrix the S/Ca and Ca/P ratios were distinctly higher than in the ITD, indicating that polysaccharide bound S supplies the anionic counterion facilitating the formation of the apatitic PTD mineral.

Bone-specific overexpression of DMP1 influences osteogenic gene expression during endochondral and intramembranous ossification.

Dentin matrix protein 1 (DMP1) is a key regulator of biomineralization within the extracellular matrix (ECM) of bone and plays a role in regulating osteogenic gene expression. Osteocalcin (OCN) is one of the most abundantly expressed non-collagenous proteins by osteoblasts. In the present study, we generated a mouse model (OC-DMP1) that overexpresses full-length DMP1 utilizing the mouse OCN promoter. Expression of genes encoding osteogenic transcription factors and ECM proteins during early post-natal development in male OC-DMP1 and wild type (WT) mice was evaluated in femurs and calvaria. Bones were dissected from n = 4 animals at 15, 30, 60 and 90-d of age. Total RNA was isolated, reverse transcribed, and real-time PCR analysis was performed. Results confirmed a difference (p < 0.05) in osteogenic gene expression between OC-DMP1 and WT mice at the specified time points. Additionally, distinctive osteogenic gene expression profiles for calvaria and femur, representing intramembranous and endochondral bone formation, were identified. These data suggest that bone-specific DMP1 overexpression changes the pattern in osteogenic gene expression pattern thereby influencing bone development. This animal model presented here provides new opportunities for analysis of in vivo roles of DMP1 in bone.