ObjectivesThe aim of this study was to investigate the effects of advancement magnitude and changes in mandibular plane angle on the stability of mandibular advancement.Materials and MethodsThis retrospective cohort study evaluated the postoperative stability of mandibular advancement in class II skeletal subjects who underwent bilateral sagittal split osteotomy. Radiographs taken preoperatively, immediately postoperatively and 1 year postoperatively were traced and analyzed using linear and angular measurements. To determine horizontal and vertical relapse, an X-Y coordinate system was established in which the X-axis was constructed by rotating S-N downward by 7° (approximation of the Frankfort horizontal plane) and the Y-axis was defined as a line perpendicular to the X-axis and passing through the point Sella. For certain reference points including point A, point B, pogonion and menton, the perpendicular distance between each point and both axes was determined and cephalometric variables were recorded as X and Y coordinates.ResultsTwenty-five subjects were studied. A significant correlation between the amount of mandibular advancement and relapse in the B point (vertical and horizontal) and the pogonion point was observed (vertical and horizontal, P<0.001). Evaluation of data demonstrated a positive correlation between the mandibular plane angle (SN/ML) change and vertical relapse in the B point (P<0.05). A simple regression model demonstrated that 74% of horizontal relapse and 42.3% of vertical relapse in the B point was related to the amount of mandibular advancement. The receiver operating characteristic test showed that 8.5 mm mandibular advancement is related to a relapse rate of 1 mm or more in the pogonion, vertically or horizontally.ConclusionThe magnitude of mandibular advancement is a stronger surgical predictor for horizontal rather than vertical relapse at the B point. Changes in mandibular plane angle (SN/ML) during surgery affect vertical, but not horizontal relapse at the B point.

Lack of protein-coding capacity is a main characteristic of long noncoding RNAs (lncRNAs) which, as molecular biomarkers, have found a novel pharmacological application in cancer and are reported to be important regulators of gene expression. H19 is reportedly involved in cancer progression and tumorigenesis. One of the most common types of head and neck cancers is oral squamous cell carcinoma (OSCC). The main objective of the present study was to evaluate the correlation of OSCC susceptibility with H19 gene in an Iranian population. This research was performed on 400 subjects of both sexes referred to the Namazi Hospital affiliated with the Shiraz University of Medical Sciences (SUMS). Individuals aged 15-88 years were divided into two groups: pathologically diagnosed patients with new-onset OSCC and healthy controls. After written and informed consent was obtained from the individuals, genomic DNA was extracted. The tetra-primer ARMS-PCR technique was performed for DNA genotyping by the use of specific primer pairs. The susceptibility of OSCC and H19 gene polymorphism sites was further analyzed (rs217727 and rs2107425). The allele and genotype frequencies of H19 rs2107425 polymorphism were similar between OSCC cases and controls. The H19 rs217727T allele frequency was significantly higher in OSCC cases (P=0.002), and the polymorphism of H19 rs217727 was associated with OSCC susceptibility in the codominant (OR=6.04, 95%CI=1.70−21.42, P=0.001 for TT genotype), dominant (OR=1.62, 95%CI=1.08−2.43, P=0.01), and recessive (OR=5.32, 95%CI=1.51−18.69, P=0.003) models. This study showed that rs217727 and OSCC susceptibility were statistically correlated in the Iranian population.

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Considering that intensive gum chewing may affect TMD signs in individuals with a gum chewing habit. It seems a longer duration of gum chewing may increase the prevalence of TMD. Individuals with a class II skeletal pattern may be affected more than others.

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