A scanning electron microscopic study of the patterns of external root resorption under different conditions

OBJECTIVE: The aim of this study was to examine if there are qualitative differences in the appearance of external root resorption patterns of primary teeth undergoing physiologic resorption and permanent teeth undergoing pathological root resorption in different conditions. MATERIAL AND METHODS: A total of 40 teeth undergoing external root resorption in different conditions were divided into 4 groups and prepared for examination under scanning electron microscopy at magnifications ranging from 20x to 1000x. Group I: 10 primary molars exfoliated due to physiologic root resorption; Group II: 10 permanent teeth with periapical granulomas showing signs of resorption; Group III:10 permanent teeth therapeutically extracted during the course of orthodontic therapy with evidence of resorption, and Group IV: 10 permanent teeth associated with odontogenic tumors that showed evidence of resorption. RESULTS: In Group I, the primary teeth undergoing resorption showed smooth extensive and predominantly regular areas reflecting the slow ongoing physiologic process. In Group II, the teeth with periapical granulomas showed the resorption was localized to apex with a funnel shaped appearance in most cases. Teeth in Group III, which had been subjected to a short period of light orthodontic force, showed the presence of numerous resorption craters with adjoining areas of cemental repair in some cases. Teeth associated with odontogenic tumors in Group IV showed many variations in the patterns of resorption with extensive loss of root length and a sharp cut appearance of the root in most cases. CONCLUSION: Differences were observed in the patterns of external root resorption among the studied groups of primary and permanent teeth under physiologic and pathological conditions.

Apoptosis in pulp elimination during physiological root resorption in human primary teeth

Pulp samples of 50 healthy human teeth with indication for extraction were examined to evaluate the role of apoptosis in pulp elimination during physiological root resorption. Two groups were formed: a test group (n=30) composed of pulp samples of primary teeth with physiological root resorption and a control group (n=20) composed of pulp samples of permanent maxillary third molars. Morphological evidence of apoptosis as well as in situ detection of cellular DNA fragmentation by TUNEL assay and detection of internucleosomal pattern of fragmentation of the genomic DNA by electrophoresis were observed. The apoptotic index of the primary tooth group was significantly higher than that of the permanent tooth group (51.01 ± 0.52 versus 25.32 ± 0.68) (p<0.001). TUNEL reaction showed intense and diffuse labeling in the pulp samples of primary teeth, which were discrete in the controls. Intense DNA internucleosomal fragmentation, a specific pattern for apoptosis, was observed in primary tooth pulps DNA by electrophoresis, in the permanent tooth pulps this pattern fragmentation of the genomic DNA for apoptosis were not present. These results seem to indicate a role of apoptosis in pulp elimination during the physiological root resorption of human primary teeth.

Cinqüenta amostras de polpas de dentes humanos hígidos com indicação para extração foram estudadas a fim de verificar a participação da apoptose na eliminação pulpar durante a reabsorção radicular fisiológica. As amostras foram divididas em 2 grupos: um grupo de estudo composto por 30 polpas de dentes decíduos hígidos com reabsorção radicular fisiológica, e um grupo controle composto por 20 polpas de terceiros molares superiores hígidos. Evidências morfológicas de apoptose, bem como detecção in situ da fragmentação do DNA genômico via reação de TUNEL e também a detecção do padrão internucleossômico de fragmentação do DNA genômico via eletroforese foram observados. O índice apoptótico foi maior no grupo de dentes decíduos (51,01 ± 0,52) quando comparado ao grupo de dentes permanentes (25,32 ± 0,68) (p<0,001). Quanto à reação de TUNEL, houve intensa marcação positiva para fragmentação do genoma no grupo de estudo, o que ocorreu de maneira discreta nos controle. A eletroforese do DNA genômico mostrou fragmentação internucleossômica, em um padrão específico de apoptose nas amostras de dentes decíduos o que não ocorreu no grupo de dentes permanentes. Estes achados parecem indicar a apoptose como um mecanismo importante na eliminação do tecido pulpar durante a reabsorção radicular fisiológica de dentes decíduos humanos.

Partial expression of Papillon-Lefèvre Syndrome.

Papillon- Lefèvre Syndrome (PLS) is a rare autosomal recessive trait, which is transmitted with an estimated frequency of one to four per million individuals. It is characterized by palmar plantar keratosis and severe early-onset periodontitis affecting both deciduous and permanent dentition. In this report, we present clinical, microbiological and leukocyte function test findings of a thirty-five year-old patient with symptoms typical of Papillon-Lefèvre Syndrome except for premature loss of deciduous and permanent dentition. The patient exhibited palmar plantar keratosis and an isolated, moderately deep periodontal pocket in the third quadrant. No anaerobic bacteria were isolated from the plaque culture. The neutrophil function test revealed defective chemotaxis and phagocytosis while intracellular killing and respiratory burst were normal.