Influence of Invisalign precision bite ramp utilization on deep bite correction and root length in adults

Objectives: To assess the influence of Invisalign precision bite ramp use on skeletal deep overbite correction and root length and volume of maxillary anterior teeth. Materials and Methods: This was a retrospective study of 60 adults with skeletal deep overbite. Patients were divided into three groups: Invisalign (Align Technology, San Jose, Calif) with precision bite ramps (Invisalign with Bite Ramps [IBR] = 12), Invisalign with no bite ramps (INBR = 22), and full-fixed appliances (FFA = 26). Cone beam computed tomography records at T1 (pretreatment) and T2 (posttreatment) were used to measure eight skeletal, nine dental, and three soft-tissue cephalometric variables. Maxillary anterior teeth root length (mm), root volume (mm³), and percent root volume loss between T1 and T2 (%) were also recorded. Results: Significant changes from T1 to T2 among the three groups were seen in ANB(^o), lower face height (%), ODI (overbite depth indicator) (^o), and U1–SN (^o). Reduction in root length was significantly less (P, .001) in the INBR and IBR groups compared to the FFA group. Reduction in root volume and percent volume loss were significantly higher in the INBR group compared to the IBR group (P, .001), but the difference between the two Invisalign groups and the FFA group was not significant. Conclusions: Skeletal deep overbite correction using Invisalign with or without bite ramps is comparable to FFA. Reduction in root length was significantly less with Invisalign compared to FFA. Bite ramps influenced root volume and volume loss but not root length.