Effect of trauma to primary incisors on root development of their permanent successors.

Trauma to the primary incisors may, by their displacement, cause developmental disturbances in the root formation of the permanent incisors. To verify this hypothesis, dental radiographs of 34 children, whose primary incisors had been previously injured, were evaluated. Only 6 children showed disturbances in root development of maxillary permanent incisors. Three cases in which trauma to the primary dentition resulted in pathology to the permanent dentition are presented, stressing the need for close periodic examination and early detection of possible developmental defects in the permanent dentition. The correlation between the presence of mineralization defects, observed in the maxillary permanent incisors of a group of school children, and the history of trauma to their primary dentition, has been reported. 1,2 The clinical and radiographic results of these studies demonstrated that most of the children with affected permanent incisors experienced trauma prior to age 5 years and during Nolla’s developmental stages 3-6 (Table 1). 3 The impact of the primary roots to the developing tooth at the time of the trauma may cause a deflection or displacement of the permanent successors. 4 The purpose of the present study was to investigate the eventual effects of trauma to the primary incisors on the root development of their permanent successors. Methods and Materials The dental records of 34 children whose maxillary primary incisors had been traumatized previously were selected from a larger sample.2 Only records of children whose clinical history and periapical radiographs taken at the time of the injury did not disclose signs of previous trauma were included. In contrast to the previous report, 2 teeth presenting with deep carious lesions were not excluded from the present study, since it is doubtful that the presence of a carious lesion in a primary crown would affect root development of the permanent successor. The majority of the children included in this report experienced trauma to their primary incisors between ages 1 and 31~ years, and the most common types of injury recorded were palatal displacement and luxation. Periapical radiographs taken at the time of trauma were evaluated for: 1. The amount of resorption of the roots of primary incisors, and 2. The developmental stage of the permanent buds according to Nolla. 3 Radiographic evaluation revealed that at the time of trauma the primary teeth had fully formed roots or were at the initial stages of root resorption. The buds of the permanent incisors were at Nolla’s developmental stages 3-6. One hundred twenty-nine fully erupted maxillary permanent incisors were examined and classified into 2 groups: (1) trauma group--comprising permanent incisors which were the successors of traumatized primary teeth; (2) nontrauma group-including 61 permanent incisors, successors to nontraumatized primary teeth (i.e., teeth located adjacent to the injured ones). The distribution of the sample according to age and dental development at the time of trauma was similar in both groups. Standardized long-cone periapical and tangential radiographs of the permanent incisors taken at a recall examination were analyzed for developmental PEDIATRIC DENTISTRY: December 1986/Vol. 8 No. 4 289 Table 1. Stages of Dental Development (according to Nolla) Stage 0 Stage 1 Stage 2 Stage 3 Stage 4 Stage 5 Stage 6 Stage 7 Stage 8 Stage 9 Stage 10 Absence of crypt Presence of crypt Initial calcification One-third of crown completed Two-thirds of crown completed Crown almost completed Crown completed One-third of root completed Two-thirds of root completed Root almost completed--open apex Apical end of root completed disturbances of the roots and the surrounding bone as follows: 1. Root dilaceration in the mesiodistal and buccolingual dimensions 2. Arrest of root formation 3. Obliteration of pulp chamber and root canal 4. Severe malformation of the root or any other phenomenon involving the surrounding bone. Root dilaceration has been defined by Andreasen 4 as a sharp deviation or bend of the root in relation to the long axis of the tooth. A slight distal angulation, frequently seen in lateral incisors, was considered as normal. The dilaceration was recorded according to its location, i.e., cervical, middle, and apical one-third of the root.