The Relation Between Incisor Growth Rate and Minimal to Maximal Dental Wear in Rabbits (Oryctolagus cuniculus)

Many authors recommend abrasive diets to prevent dental overgrowth in pet rabbits. Research, however, indicates that growth adapts to wear. Furthermore, growth in the absence of wear has only been qualitatively but not quantitatively determined. The present study therefore aimed to quantify the growth-wear relation in rabbit incisor teeth by inducing minimal to maximal wear and using the obtained data as well as previously published values. Twelve rabbits were fed a hay-only diet as a control or a gruel as a low-wear diet in a cross-over design for 21 days each. Thereafter, in all animals while on the hay-only diet, the left incisor pair was repetitively trimmed out of occlusion for a maximum of 54 days. Animals received ample gnawing materials except when gruel-fed. Tooth length, growth, and wear were documented throughout. The diet affected proxies (i.e., measurements) only in the maxillary incisors. Growth in response to dental trimming on the other hand was faster in the mandibular incisors. Data indicate a linear adaptation of growth to wear with slopes lower than 1 and a positive intercept in maxillary and mandibular incisors. Although this proposes basal growth and incomplete responsiveness to wear, measurement methods likely cause underestimation and overestimation of the slopes and intercepts, respectively. Importantly, wear always occurs, even when rabbits are fed liquid diets without gnawing opportunities. The present study confirms the adaptive character of growth to wear in rabbit incisors and questions the necessity of dietary abrasiveness to prevent incisor overgrowth.