Correlation between occlusal contact and root resorption in teeth with periodontal disease.

BACKGROUND AND OBJECTIVE: The present study was designed to investigate the influence of occlusal forces on radicular resorption in teeth with periodontal disease. The occlusal forces are a cause in the aggravation of the periodontal disease and therefore influences in the increase the extension and the depth of the radicular resorption. MATERIAL AND METHODS: We quantified radicular resorption, its extension across the radicular surface and its depth, in 88 teeth with periodontal disease with and without occlusal contact, pertaining to patients between 43 and 91 years of age. A histological method was used to obtain 6-µm-thick sections. The sections were observed under an Olympus BX40 optical microscope and processed by an image analysis program. Measurements of length and area were used to calculate the percentages of surface and volume of cement reabsorbed. RESULTS: In both groups presenting periodontal pathology (groups 2 and 3) the percentages of the surface and volume of reabsorbed cement were greater in those teeth with antagonist contact. The greatest percentages of radicular resorption were observed in teeth of group 3 showing antagonism. CONCLUSION: The severity of periodontal disease increases the extension and the depth of the radicular resorption, and the presence of antagonist forces aggravates the resorption.

The osteoinductive potential of MTA (Mineral Trioxide Aggregate): a histologic study in rabbits

The objective of this study was to investigatebone response after implantation of MTA (MineralTrioxide Aggregate) in the rabbit mandible.Experiments were carried out on the rightmandibular body of 8 adult male rabbits. Theanimals were divided into two groups (controlgroup and test group). In this in vivo study, MTAwas used as an interpositional graft material incritical-size bone defects of rabbit mandibles.The animals were sacrificed on day 30 after surgery.The samples obtained from the mandibleswere subjected to histological procedures, whichpermitted the collection of sections with a thicknessof 60±10ìm. The sections were stained withHaematoxylin and Eosin and Goldner Trichromestain and examined under a light microscope.No important inflammatory reactions weredetected in any of the samples of the treatedgroup. The results confirm the excellent biocompatibilityof MTA. The implantation of MTA inbone defects led to bone regeneration 4 weeksafter surgery. However, the growth rate was notsignificant and the amount of newly formed bonewas limited with the use of MTA in this specificapplication. Sample examination did not suggestcomplete evidence of new bone growth from eitheran inductive or conductive perspective.The objective of this study was to investigatebone response after implantation of MTA (MineralTrioxide Aggregate) in the rabbit mandible.Experiments were carried out on the rightmandibular body of 8 adult male rabbits. Theanimals were divided into two groups (controlgroup and test group). In this in vivo study, MTAwas used as an interpositional graft material incritical-size bone defects of rabbit mandibles.The animals were sacrificed on day 30 after surgery.The samples obtained from the mandibleswere subjected to histological procedures, whichpermitted the collection of sections with a thicknessof 60+-10microm. The sections were stained withHaematoxylin and Eosin and Goldner Trichromestain and examined under a light microscope.No important inflammatory reactions weredetected in any of the samples of the treatedgroup. The results confirm the excellent biocompatibilityof MTA. The implantation of MTA inbone defects led to bone regeneration 4 weeksafter surgery. However, the growth rate was notsignificant and the amount of newly formed bonewas limited with the use of MTA in this specificapplication. Sample examination did not suggestcomplete evidence of new bone growth from eitheran inductive or conductive perspective

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Morphological study of root surfaces in teeth with adult periodontitis.

BACKGROUND: Our study correlates the histological alterations in the cementum (especially resorption areas) of teeth with the different stages of adult periodontitis. METHODS: Sixty-seven teeth affected by adult periodontitis and 7 healthy teeth extracted from patients over 40 years old were used. The teeth were divided into 3 groups according to radiographic data: group 1: five teeth with bone loss less than one-third of the normal alveolar height; group 2: thirty-one teeth with bone loss between one and two thirds; and group 3: thirty-one teeth with bone loss greater than two thirds. The samples were prepared for light and scanning electron microscopy, considering the gingival, middle, and apical thirds in each root. RESULTS: Two control teeth, 4 teeth in group 1, and all teeth in groups 2 and 3 showed resorption areas. Regarding the gingival third, the control teeth did not show any resorption, while 25% of affected teeth in group 1, 38.7% of teeth in group 2, and 35.5% of teeth in group 3 exhibited resorption. Regarding the middle third, 50% of affected teeth belonging to the control group and group 1; 67.7% of teeth in group 2; and 87.1% of teeth in group 3 showed resorption. Regarding the apical third, all teeth belonging to the control group and group 1 showed resorption, while 93.5% and 87.1% of teeth in groups 2 and 3, respectively, exhibited resorption. Most of the resorptions did not extend beyond the cementum. However, in 29.0% of teeth in group 2 and 38.7% of teeth in group 3, resorption had spread as far as the dentin. All the lesions in the control group and group 1 were practically repaired, while only 71.0% of teeth in group 2 and 61.3% of teeth in group 3 showed some sign of reparation. However, in groups 2 and 3, practically all lesions affecting dentin were repaired. CONCLUSIONS: These data suggest that the spread of root resorption is associated with inflammation. This study also suggests that the capacity for repair of root resorption is diminished with greater severity of periodontitis.

Variation in articular cartilage in rabbits between weeks six and eight.

BACKGROUND: Previous studies of variation in cartilage characteristics with age have involved comparison of young and adult individuals, but no data on short-term age-related change are available. Such data are important for studies of the response of cartilage to experimental stimuli in young rabbits, to distinguish the response to the stimuli from accompanying age-related changes. METHODS: We used light microscopy to study the thickness, cell density, and degree of histological definition of articular cartilage on the femoral trochlea of 6-, 7-, and 8-week-old rabbits. RESULTS: Thickness and cell density both decline significantly with age. The decline in cell density is more marked in surface layers of cartilage and is accompanied by an increase in the safranin O-staining affinity of the extracellular matrix and an extension of this affinity towards the surface. CONCLUSIONS: Our results indicate that the synthesis of matrix components becomes more important relative to proliferative activity. The traditionally defined histological layers (zones I, II, III, and IV) are not clearly distinguishable in rabbits of this age. In 6- and 7-week old animals only a "surface" (I/II) and a "deep" layer (III) can be distinguished. By 8 weeks, zones I and II are well defined but the mineralization front (marking the boundary between zones III and IV) is still absent.