Gene Expression in MasseterM. after Orthognathic Surgery and in Controls

Method: 50 adult patients (mean age 23.6y) divided in groups with mandibular prognathia (15), retrognathia (20) and untreated controls (15) were involved. Tissue samples were taken from controls during third molar extraction and from patients before (T1) and six months following surgery (T2). In a first step 15 Miroarrays (42525 Micro-chip:SurePrint G3. Agilent) were applied in 3 controls, 3 prognathic and 3 retrognathic patients (T1, T2)  to identify entities to be differentially expressed  between the groups. Relative quantification for 12 genes of interest (developmental, fast and slow myosin heavy chain mRNA (MYH), Calcineurin, COX2, IGF, Myostatin) was performed with real time PCR. Gene regulations were analyzed with the relative expression software tool. Unpaired t test and ANOVA served for statistics.  

Result: : Microarrays showed decreasing of differentially gene expression between the controls and the patients at T2 e.g. a convergence of gene expression after surgery (p<0.05), more decreased in prognathic than in retrognathic patients. RT-PCR show increase of developmental MYH and switching from slow to fast MYH which signalize improvement of masticatory function. Calcineurin,  which is important in the stretching cascade showed in retrognathics  a significant higher up regulation. Myostatin expression was 4fold higher in retrognathics.

Conclusion: The microarray findings give evidence that function follows form six month after surgery in orthognathic patients. But the regeneration process is more advanced in prognathic than in retrognathic patients. The up regulation of stretching factor could delay the regeneration process.