Relationship between periodontal furcation involvement and molar cervical enamel projections

A total of 78 individuals ages 21 to 61 years with periodontal furcation involvement was examined for the presence of cervical enamel projections on the buccal surfaces of molar teeth. The furcal defects and cervical enamel projections (CEPs) of molars were diagnosed by probing, periapical roentgenographs, flap operation and inspection. Plaque index (PlI) and gingival index (GI) were recorded for the buccal and lingual surfaces of molars examined. The percentage of CEPs in the 78 individuals examined was 67.9%. The prevalence of CEPs in all molars examined was 45.2%. The prevalence of CEPs in molars with and without furcal involvements were 82.5% and 17.5%, respectively. The frequency of CEP in molars occurred in the following order: mandibular first molars, maxillary first molars, mandibular second molars and maxillary second molars. Statistical analyses (Chi-square test) revealed a significant difference between periodontal furcation involvements and the presence of CEPs. Results of this study also indicated that the furcal involvements with CEPs were associated with poor oral hygiene as measured by GI and PlI.     

Immunohistochemical localization of oncostatin M in epithelialized apical periodontitis lesions

Aim  To investigate the in situ location of oncostatin M (OSM) in epithelialized apical periodontitis lesions.
Methodology  Thirty periapical lesions of pulpal origin were collected with informed consent from patients at the time of apical surgery. Tissue specimens were fixed with 10% buffered formalin overnight, dehydrated in an ascending series of graded alcohol, and embedded in paraffin. Five micron sections from formalin-fixed, paraffin-embedded specimens were examined by immunohistochemistry. In addition, another section from each specimen was stained with haematoxylin and eosin to assess the presence of inflammatory infiltrates. Differences in OSM expression between tissue with low and high levels of inflammation were subsequently analyzed by Fisher's exact test.
Results  Based on histological examination of haematoxylin and eosin stained sections, all specimens revealed the morphology of epithelialized apical periodontitis lesions. The results from immunohistochemistry demonstrated that OSM stain was detected in the inflammatory infiltrates, epithelium, connective tissue, and endothelium. The OSM signal was mainly expressed in endothelial cells (100%) followed by inflammatory cells (93.33%), epithelial cells (53.33%), and fibroblasts (16.67%). In addition, OSM expression was significantly higher in epithelialized apical periodontitis with higher levels of inflammatory infiltrates ( P  < 0.001).
Conclusions  Oncostatin M was found to be expressed in epithelialized apical periodontitis lesions and would form part of the cytokine network involved in the disease process of apical periodontitis.     

Fracture resistance of compomer and composite restoratives

This study evaluated and compared the fracture toughness of compomers and composites. Three compomer (Compoglass F [CG], Vivadent; F2000 [FT], 3M-ESPE; Dyract Posterior [DP], Dentsply) and three composite (Tetric Ceram [TC], Vivadent; Z250 [ZT], 3M-ESPE; Esthet X [EX], Dentsply) restoratives were selected for the study. Single-edged notched specimens (25 x 2 x 2 mm) were fabricated according to manufacturers' instructions and conditioned in distilled water at 37 degrees C for one week prior to testing. Seven specimens were made for each material. The specimens were loaded to failure using an Instron microtester with a crosshead speed of 0.5 mm/minute. Data were subjected to ANOVA/Scheffe's test and Independent Samples T-test at significance level 0.05. The mean fracture toughness (K(IC)) ranged from 0.97 to 1.23 MPam 1/2 for compomers and 1.75 to 1.92 MPam 1/2 for composites. The fracture toughness of compomers was significantly lower than their composite counterparts. No significant difference in K(IC) values was observed among the different composites. When the compomers were compared, FT had significantly higher fracture toughness than DP and CG. In view of their poorer resistance to crack propagation, compomers are not recommended for use in stress-bearing areas.     

Effect of various surface protections on the margin microleakage of resin-modified glass ionomer cements

STATEMENT OF PROBLEM: Because conventional glass ionomer cements are moisture sensitive, a surface coating is recommended during the initial setting stage. It is unknown whether resin-modified glass ionomer cements also need surface protection. PURPOSE: This study investigated the effect of various surface protections on microleakage with Class V resin-modified glass ionomer restorations. MATERIAL AND METHODS: Forty extracted molars with buccal and lingual Class V cavity preparations were restored with a resin-modified glass ionomer (Fuji II LC). The occlusal margin of each restoration was on enamel and the cervical margin on dentin. After immediate finishing and polishing, the teeth were divided into 4 groups according to the following surface protection treatments: group I, unprotected; group II, Fuji varnish; group III, resin adhesive; and group IV, acid etching and resin adhesive. After these procedures, all teeth were stored in isotonic saline for 24 hours, thermocycled 1500 times at 5 degrees C to 60 degrees C, and soaked in dye solution for 24 hours. The teeth then were longitudinally sectioned and observed under a stereomicroscope. The degree of dye penetration was recorded and analyzed with the Kruskal-Wallis and Mann-Whitney tests (P<.05) RESULTS: None of the 4 groups demonstrated complete margin sealing at either the occlusal or cervical margins. Groups II and III displayed the least microleakage at cervical margins; a significant difference existed between groups I and III (P=.034). Compared with the other 3 groups, group IV showed significantly greater microleakage at the cervical margins. CONCLUSION: Although resin-modified glass ionomers can be finished immediately, they remain moisture sensitive. Within the limitations of this study, the results suggest that resin adhesive should be used as a surface protection to reduce margin microleakage of resin-modified glass ionomer restorations.     

Bone changes in the mandible following botulinum neurotoxin injections

In this study, botulinum neurotoxin type A (BoTx/A) was injected into the temporalis and masseter muscles of growing rats to induce masticatory hypoactivity. Sixty, 30-day-old, male Long-Evans rats were randomly divided into four groups. BoTx/A was bilaterally injected in the masseter muscles in group I, in the temporalis muscles in group II, and into both the masseter and the temporalis muscles in group III. Group IV served as the control in which saline was bilaterally injected into both muscles. Forty-five days after the injections, the rats were sacrificed. Observation of cortical bone thickness from bone biopsies of the right halves of the mandibles, evaluation of the volume of masseter and temporalis muscles with a plethysmometer, and scanning of bone mineral density (BMD) of the skull and mandibular bone structure with dual-energy X-ray absorptiometry were performed. One-way analysis of variance was employed to analyse measurements of muscle volume, BMD, and cortical bone thickness among the groups. The least square difference was then used to determine significance. Reduced cortical bone thickness and BMD of the skull and mandibular bone structure were observed. The volumes of the temporalis and masseter muscles injected with BoTx/A were smaller. Masticatory hypofunction affects bone structure during development.     

Gingival crevicular fluid lactoferrin levels in adult per iodontitis patients

The present study was designed to determine in a cross-sectional study whether there was any relationship between the levels of lactoferrin in gingival crevicular fluid and clinical periodontal parameters. Crevicular fluid was collected from individual sites using standardized filter paper strips (clinically healthy sites, N=23; periodontitis sites, n=66) and evaluated for lactoferrin by enzyme-linked immunosorbent assay. The data showed that: (1) the total amounts of lactoferrin were 0.003-0.021 ng (30 second sample) (average 0.009±0.005 ng) in a clinically healthy periodontium group and 0.016-3.847 ng (30 second sample) (average 0.575±0.069 ng) in adult periodontitis patients (statistically significantly higher in adult periodontitis patients); and (2) the total amounts of lactoferrin were significantly correlated with clinical parameters,     

Morphology of the palatal vault of primary dentition in transverse view

The purpose of this study was to investigate the transverse view of the morphology of the palatal vault in the primary dentition at the primary second molar level. Observations were obtained from 150 dental stone casts of normal children (78 boys and 72 girls; aged four to five years). Palatal width, palatal depth, arch width, and primary second molar angulation were measured. There were no significant differences in palatal depth and primary second molar angulation between boys and girls or between the right and left sides. However, girls had a statistically significantly narrower upper dental arch width and palatal width than did boys. Palatal widths on the left side were statistically significantly larger than those on the right side for both sexes. Asymmetry in the palatal width greater than two mm was present in 21.8% of boys and 16.7% of girls. There was a correlation between buccal tipping in the upper primary second molar and greater palatal width.