30 Prevalence of Root Resorption and Position of Maxillary Canine Impaction

Wednesday, March 21, 2012: 2:30 p.m. - 4 p.m.
Presentation Type: Oral Session
B. YAN1, L. WANG2, H. FIELDS3, and Z. SUN3, 1Laboratory of Image Science and Technology, Southeast University, Nanjing, China, 2School of Stomatology, Nanjing Medical University, NanJing, China, 3Orthodontics, Ohio State University, Columbus, OH
Objectives: This study examined the prevalence of root resorption (RR) associated with maxillary canine impaction in a Chinese population, and assessed the relationship between RR prevalence and impacted-canine positions by using cone-beam computed tomography (CBCT).

Methods: Pre-treatment CBCT images (Newtom VG, 0.25mm voxel-size) of 150 Chinese orthodontic patients (12-30 years, either gender) with unilateral impacted canines were randomly coded and analyzed in Dolphin-3D and Mimics programs. Maxillary lateral (U2), central (U1) incisors and first premolar (U4) with or without RR (surface defects>1mm in length and depth) on the impaction and contralateral normal sides were counted. RR prevalence was defined as Numberteeth with RR/Numberteeth examined. Based on the position of the canine cusp-tip relative to U2 root long-axis and mesial surface, impacted canines were categorized into 6 groups: mid-buccal, disto-buccal, mesio-buccal, mid-palatal, disto-palatal and mesio-palatal positions. RR prevalence difference between impacted and control sides was compared and RR distribution with impacted-canine positions were analyzed by Chi-square and Fisher’s exact tests.

Results: Overall RR was detected on the impaction-side U2/U1/U4 roots with a 25%/14%/10% prevalence, respectively, significantly greater than their control-side counterparts (1%/1%/0%, respectively). Impaction-side RR prevalence varied significantly (P<0.05) with impacted-canine positions. RR on U2 was most prevalent when canines were at mid-buccal (50%), mesio-palatal (37.4%) and mid-palatal (33.3%) positions; RR on U1 was most prevalent when canines were at mesio-palatal (34.6%) and mesio-buccal (23.8%) positions; RR on U4 was most prevalent when canines were at disto-palatal (23.5%) and disto-buccal (14.9%) positions. When canine positions were combined, RR at U2/U1/U4 were most prevalent when canines were at middle/mesial/distal (42.1%/29.8%/17.2%, Chi-square tests, P<0.05) positions, respectively.

Conclusions: Maxillary canine impaction increased the prevalence of root resorption at adjacent lateral, central incisors and first premolars. The mesio-distal proximity of these roots to impacted maxillary canine cusp-tip influences their relative risk of root resorption.

This abstract is based on research that was funded entirely or partially by an outside source: International Health Support Project of Jiangsu Province,China

Keywords: Assessment, Canine impaction, Digital image analysis, Orthodontics and Resorption
See more of: Diagnostic Sciences I
See more of: Diagnostic Sciences