Coronal Displacement of Cementum in Impacted Teeth: Age Determination

Dental cementum is a vital tissue which demonstrates continuous apposition throughout the life of the tooth. This study was conduct on 101 impacted and 106 erupted mandibular third molar teeth extracted from healthy patients, aged 18-30 years. The buccolingual ground sections were prepared. The distance between the edges of enamel and cementum were measured with micrometer attached with light microscope. The study indicated that the cementum in impacted teeth displaced toward coronal during aging. This phenomenon could be used in forensic odontology in age estimation. Key word: Cementum enamel cemento-enamel junction impacted mandibular third molars age estimation INTRODUCTION study we focus on the coronal displacement of cementum Cementum is the calcified tissue that surrounds the dentine and forms the attachment site for the periodontal MATERIALS AND METHODS fibres that link the tooth to alveolar bone. In cementum formation, hypermineralized layer of extracellular matrix Our sample consists of 207 freshly extracted alternate with less mineralized layers. The first layer of permanent teeth third mandibular molar (101:106, acellular cementum is produced before the tooth erupts impacted: erupted) collected from Government Dental and further layers are added during and after eruption. College, Rohtak. In addition to the extraction date of the Cementum layer consist primarily of uncalcified dense tooth and reason for extraction, the records contain the bundles of collagen fibrils. These bundles later become patient’s date of birth and ethnicity. In all cases, tooth mineralized by hydroxyapatite crystals, whose changing extractions were performed as part of essential dental orientations may be responsible for the optical effect care. Additional care was taken in the extraction of alternating dark and translucent layers. The first use procedure to minimize damage to teeth; teeth which were of cementum in human age estimation began with broken during extraction were excluded from the study. measurements of width of the total cementum layer, The teeth were obtained from healthy patients ranging rather than with counts of incremental lines [1]. Many in age between 18 to 30 years. questions remain regarding the mechanisms of tooth The teeth were rinsed in running water and were cementum annulation and its influencing factors, placed in formalin solution for 17 days. The buccolingual particularly concerning the interpretation of seasonal ground sections were prepared from each specimen. The increments [2-3]. Two major factors are found to be distance between the enamel and cementum, or the responsible for these changes environmental effects amount of cementum overlapping the cervical region of and aging [4]. the ground sections of teeth, were measured by means of Erupted teeth are directly affected by conditions a micrometer attached to a light microscope. The such as mastication, tooth brushing, and by aging measurements were (x) when there was a distance while impacted tooth remain intact and are only affected between cementum and enamel (y) was assigned when by aging cementum deposition on a healthy tooth there was an edge to edge relationship and (z) in case of continues throughout life and a relationship exists cementum overlap. The data were entered into a computer between age and cementum thickness [5]. In the present using FOXPRO software and a data file generated. The with age in impacted teeth for age determination. World J. Med. Sci., 1 (2): 117-118, 2006 118 Table 1: The results of cementum enamel distance (μm) measurements in impacted and erupted teeth in different age groups (years) Cementum and enamel distance (μm) (mean + SD) ---------------------------------------------------------------Age groups Impacted teeth Erupted teeth 18-20 x5.92±0.21 z1573.2±0.34 21-23 z98.42±0.34 z156.21±0.42 24-26 z137.25±0.23 z156.24±0.43 27-30 z185.23±0.24 z156.27±0.43