OBJECTIVE: This study examined bone microstructure restoration after rapid maxillary expansion (RME) with and without corticotomy over multiple retention periods. METHODS: Eighteen male Dorper sheep were randomly distributed into three groups (n = 6 each group): group 1, RME with corticotomy on the buccal and palatal sides; group 2, conventional RME treatment; and group 3, no treatment. Post-RME, trabecular bone microstructure and new bone formation were evaluated by using microcomputed tomography (microCT) and histomorphometry after a 4- or 12-week retention period. Intergroup differences in bone quality and bone remodeling were analyzed by using two-way analysis of variance with Bonferroni post-hoc test. RESULTS: The bone volume fraction (bone volume [BV]/total volume [TV]) values relative to the control in groups 1 and 2 were 54.40% to 69.88% after the 4-week retention period and returned to approximately 80% after the 12-week retention period. The pooled BV/TV values of the banded teeth in groups 1 and 2 were significantly lower than those of the control after the 4-week retention period (p < 0.05). However, after the 12-week retention period, the pooled BV/TV values in group 2 were significantly lower than those in groups 1 and 3 (p < 0.05). Histomorphological analysis showed that the new bone formation area in group 1 was approximately two to three times of those in group 2 and control. CONCLUSIONS Corticotomy significantly enhanced the restoration of bone quality after the retention periods for banded teeth. This benefit might result from the increased new bone formation after corticotomy.

Deletions and amplifications of genes often occur during multistep progression from oral precancer, seen as oral epithelial dysplasia (OED) to cancerous stage. These genetic alterations could be used as markers to aid in detection of oral squamous cell carcinomas (OSCC). This study explored the use of multiplex ligation-dependent probe amplification (MLPA) technique in detecting OSCC and OED specific genetic alterations. MLPA was used to detect gains and losses of 106 genes in DNA extracted from frozen tissue samples of 10 OSCC and 10 noncancer patients. Two biopsies of OED were analyzed to explore the alterations in oral potentially malignant disorders. There were significant differences (p<0.001) in the number of alterations in OSCC and dysplasia compared to non-cancer samples respectively. The most frequently altered genes in OSCC were PTP4A3, RECQL4, ATM, and KLK3 (60%). Five genes (MYC, SLA, TNFRSF1A, MESDC1, MIF) were altered in 50% of OSCC samples. These nine genes were specific to OSCC samples (p<0.05). Some genes, including MYB, MET, CASP2, SLA and PTEN occurred in 50% of OED samples. MLPA was able to detect genetic alterations, that are present only in the OSCC samples and showed potential to be used as an adjunctive tool in early diagnosis of OSCC.