Orofacial Cleft and Mandibular Prognathism—Human Genetics and Animal Models

Many complex molecular interactions are involved in the process of craniofacial development. Consequently, the network is sensitive to genetic mutations that may result in congenital malformations of varying severity. The most common birth anomalies within the head and neck are orofacial clefts (OFCs) and prognathism. Orofacial clefts are disorders with a range of phenotypes such as the cleft of the lip with or without cleft palate and isolated form of cleft palate with unilateral and bilateral variations. They may occur as an isolated abnormality (nonsyndromic—NSCLP) or coexist with syndromic disorders. Another cause of malformations, prognathism or skeletal class III malocclusion, is characterized by the disproportionate overgrowth of the mandible with or without the hypoplasia of maxilla. Both syndromes may be caused by the presence of environmental factors, but the majority of them are hereditary. Several mutations are linked to those phenotypes. In this review, we summarize the current knowledge regarding the genetics of those phenotypes and describe genotype–phenotype correlations. We then present the animal models used to study these defects.

Risk of Malocclusion Among Patients Undergoing Single-Stage Versus Two-Stage Cleft Palate Repair

Objective Evaluate impact of single-stage versus staged palate repair on the risk of developing malocclusion among patients with cleft palate (CP). Design Retrospective cohort study 2000–2016 Setting Academic, tertiary children’s hospital. Patients Patients undergoing CP repair between 1999–2015. Interventions CP repair, categorized as either single-stage or staged. Main Outcome Measure Time to development of Class III malocclusion. Results 967 patients were included; 60.1% had a two-stage CP repair, and 39.9% had single-stage. Malocclusion was diagnosed in 28.2% of patients. In the model examining all patients at ≤5 years ( n = 659), patients who were not white had a higher risk of malocclusion (HR 2.46, p = 0.004) and staged repair was not protective against malocclusion (HR 0.98, p = 0.91). In all patients >5 years ( n = 411), higher Veau classification and more recent year of birth were significantly associated with higher hazard rates ( p < 0.05). Two-staged repair was not protective against developing malocclusion (HR 0.86, p = 0.60). In the model examining patients with staged repair ≤5 years old ( n = 414), higher age at hard palate closure was associated with reduced malocclusion risk (HR 0.67, p < 0.001) and patients who were not white had increased risk (HR 2.56, p = 0.01). In patients with staged repair >5 years old, more recent birth year may be associated with a higher risk of malocclusion (HR 1.06, p = 0.06) while syndrome may be associated with lower risk of malocclusion diagnosis (HR 0.46, p = 0.07). Conclusion Our data suggests that staged CP repair is not protective against developing Class III malocclusion.

Association between Crowding and the Effective Maxillary and Mandibular Length among Orthodontic Patients of Kathmandu, Nepal.

Background: During orthodontic consultation, the most frequent major complaint of the patients is dental crowding, which is caused by a disparity between the arch length and tooth size. Objective: The purpose of this study was to evaluate the association between crowding and the effective maxillary and mandibular length in Nepalese orthodontic patients.Methods: The orthodontic records of 390 people (from January 2018 to December 2020) were randomly selected and classified into three skeletal malocclusions based on the ANB angle (Angle formed by point A and point B at the nasion). Subjects with skeletal malocclusions were subdivided into two groups depending on the degree of crowding in the mandibular arch: Group 1 had crowding of < 3mm, and Group 2 had crowding of >3mm. On pretreatment casts, digital vernier calipers (Digimatic, Precise, India) were used to assess dental arch crowding, whereas, on a pretreatment lateral cephalogram, digital cephalometric analysis (Vistadent OC 1.1, USA) was done to quantify effective maxillary and mandibular length. Inter-group comparisons were assessed using a one-way analysis of variance. The correlation was assessed by Pearson’s correlation coefficient (p≤0.05).Results: There was a statistically significant difference in effective maxillary and mandibular length among skeletal malocclusions (p<0.05). Skeletal Class II malocclusion had the greatest mandibular crowding, while skeletal Class III malocclusion had the least. The effective maxillary and mandibular lengths and dental crowding had a significant but weak inverse correlation, whereas a strong but moderate positive correlation existed between the maxillary and mandibular effective lengths (r=0.674) and also between maxillary and mandibular crowding (r=0.631).Conclusion: Effective maxillary length was highest in skeletal class II malocclusion whereas effective mandibular length was highest in skeletal class III malocclusion. The shorter effective maxillary and mandibular lengths showed a weak association with dental crowding.

Nonsurgical treatment of a hyperdivergent skeletal Class III patient with mini-screw–assisted mandibular dentition distalization and flattening of the occlusal plane

ABSTRACT Treatment of hyperdivergent skeletal Class III malocclusion is challenging for orthodontists, and orthognathic-orthodontic treatment is usually required. This report presents the successful nonsurgical treatment of a 20-year-old man who had a skeletal Class III malocclusion with anterior open bite, anterior and posterior crossbite, hyperdivergent growth pattern, steep occlusal plane, early loss of three first molars, and an uncommon convex profile with a retruded chin. An orthodontic camouflage treatment plan was chosen based on the etiology and the patient's complaints. Tooth #37 was extracted. Miniscrews were used for uprighting and intruding of the lower molars, distalization of the lower dentition, and flattening of the occlusal plane. After 34 months of active treatment, Class I relationships, proper anterior overjet and overbite, flat occlusal plane, and an esthetic facial profile were achieved. The results demonstrated that the biomechanics involved in the nonsurgical treatment assisted with miniscrews to distalize the mandibular dentition and flatten the occlusal plane while keeping the mandibular plane stable was effective for treating this hyperdivergent skeletal Class III patient with a convex profile and anterior open bite.