Factors Contributing to Canine Impaction in Patients with Unilateral Cleft Lip and Palate (UCLP) Undergoing Alveolar Bone Grafts (ABG)

Abstract

Background: Patients with unilateral cleft lip palate (UCLP) undergo alveolar bone grafting (ABG) to unite the maxillary bony segments and allow for proper eruption of the permanent canine. The aim of this study was to assess the incidence of canine impaction in the UCLP patient population and identify pre-graft and surgical factors as well as dental anomalies that are associated with impaction. Materials and Methods: This study included 257 patients with UCLP who received alveolar bone grafting at Seattle Children’s Hospital. Electronic health records were reviewed to obtain data on cleft information, pre-graft procedures, and surgical details. Dental anomalies were identified through panoramic/cephalometric radiographs and intraoral photo taken before ABG and up to 2 years after ABG. T-tests, chi-square tests and logistic regression analysis were used to evaluate incidence of canine impaction and test for associations with pre-graft factors, surgical factors, and non-cleft factors. Results: Of the 257 patients included in the study, 56% were male with a mean age of 9.2 years old at the time of ABG. Left-sided clefts (63%) were more common than right-sided clefts (37%). The incidence rate of canine impaction in this cohort of patients was 27% (N=257). Clefts extending to the secondary palate were more likely to have impacted canines (30% vs 12%, p = 0.017). Patients with a hypodivergent facial pattern also had a higher incidence of canine impaction (low angle: 46%; high angle: 29% versus 22% normal angle, p = 0.042). Logistic regression indicated canine impaction was more likely in females than males (adjusted odds ratio [OR] = 2.1, p = 0.015), root development of less than 1/3 expected total length at time of of graft (OR= 3.36, p = 0.024), extraction of primary canine (OR = 2.3, p=0.009) and greater permanent canine angulation (OR = 1.1, p <0.0001). No associations between canine impaction and pre-graft orthodontic expansion nor re-grafting were detected. Conclusion: There is a substantially higher incidence of canine impaction in cleft populations compared to non-cleft populations. Multiple factors including pre-graft extraction of the primary canine and increased canine angulation were associated with permanent canine impaction and should be considered when managing patients with UCLP.