Effects of toothbrushing frequency on proliferation of gingival cells and collagen synthesis.

BACKGROUND: Mechanical stimulation by toothbrushing enhances proliferation of fibroblasts and junctional epithelium (JE). These changes in gingiva may depend on the interval between toothbrushing. The effects of toothbrushing frequency on proliferation of gingival fibroblasts and basal cells of JE were evaluated. METHODS: Twelve mongrel dogs were used. Each tooth was brushed for 20 s at 1.96 N. The subepithelial connective tissue of JE was examined for proliferating cell nuclear antigen (PCNA)-positive fibroblasts and procollagen type-I C-peptide (PIP)-positive fibroblasts. JE was examined for PCNA-positive basal cells. RESULTS: Gingiva that received brushing twice a day showed increases in the density of fibroblasts and ratio of PCNA-positive fibroblasts to total fibroblasts at 4 weeks. The ratio of PIP-positive fibroblasts increased at 8 weeks in gingiva brushed twice a day and once a day. PCNA-positive basal cell ratio increased at 4 weeks in gingiva brushed twice a day and once a day. CONCLUSIONS: A high frequency of brushing was associated with increased numbers of PCNA-positive fibroblasts, PIP-positive fibroblasts and PCNA-positive basal cells. Gingival cell proliferation increased and reached a plateau earlier in gingiva brushed twice a day than in gingiva brushed once a day.

Relationship between blood triglyceride levels and periodontal status.

OBJECTIVES: The literature suggests that a link exists between the presence of periodontal disease and impaired lipid metabolism. However, most studies have focused on patients in private clinics or university hospitals. In the present study, we assessed associations between blood chemistry variables and periodontal disease status in rural communities of Japan. METHODS: A total of 823 residents participated in a comprehensive health screen. The medical screen included measurement of body mass index, blood pressure, hematocrit and blood chemistry, including levels of hemoglobin, total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides, glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), gamma-glutamyl transpeptidase (gamma-GTP), creatinine, and plasma glucose. Periodontal status was assessed using the CPI scoring method. Of those participating, 133 subjects with a CPI of 4 (periodontal disease group) and age- and gender-matched control subjects with a CPI of less than 3 were selected for analysis. RESULTS: The mean triglyceride level was significantly higher for the diseased group than for the control group (p < 0.05). The mean HDL-C level was higher for the control group than for the diseased group, although the difference was not statistically significant. Logistic regression model analysis revealed a significant relationship between elevated triglycerides (> 149 mg/dl) and the presence of periodontal disease (OR = 2.26 vs. < or = 149 mg/dl, p = 0.014). CONCLUSION: The results indicate that serum triglyceride level might be a potential indicator for the presence of periodontal disease, suggesting the need for community-based longitudinal studies.

Spatial extent of gingival cell activation due to mechanical stimulation by toothbrushing.

BACKGROUND: Mechanical stimulation by toothbrushing enhances gingival fibroblast proliferation and collagen synthesis, and reduces inflammatory cell infiltration. The aim of this study was to investigate the spatial extent of proliferation of fibroblasts and endothelial cells in dog gingiva in response to mechanical stimulation by toothbrushing. METHODS: All maxillary fourth premolars and mandibular first molars of 6 mongrel dogs were used. Dental plaque was removed with a curet. One of each pair of bilateral teeth (in the same jaw) was assigned to the brushing group, and the corresponding tooth (opposite side) was assigned to the control group. The Bass method was used to brush the limited mesial half of the tooth at 1.96 N for 20 seconds with a fitted plastic stent. Immediately before fixation of tissue, the surface of brushed gingiva was notched to indicate the borderline between the brushed and non-brushed areas. Histometrical analyses of the sections were performed using assays for proliferating cell nuclear antigen (PCNA) and von Willebrand factor. RESULTS: The numbers of fibroblasts and PCNA-positive fibroblasts in the subepithelial connective tissue adjacent to oral sulcular epithelium significantly increased in brushed gingiva, not only in the brushed area but also in the non-brushed area 0 to 0.5 mm from the notch. Increased numbers of vascular endothelial cells were observed only in the brushed area. CONCLUSION: The effect of mechanical stimulation by toothbrushing on gingival cell proliferation was not observed more than 0.5 mm from the brushed area. These results indicate that effective activation of gingival cell proliferation requires mechanical stimulation of gingiva in all areas.

Optimum force and duration of toothbrushing to enhance gingival fibroblast proliferation and procollagen type I synthesis in dogs.

BACKGROUND: Toothbrushing enhances gingival fibroblast proliferation, which promotes wound healing. Optimum force and duration of toothbrushing for stimulation of fibroblast proliferation are key factors in maximizing effects of toothbrushing on periodontal wound healing. We therefore evaluated the effects of different durations and forces of toothbrushing on proliferative activity and procollagen synthesis of gingival fibroblasts. METHODS: Twelve dogs were used. In each dog, buccal gingivae of 12 teeth were examined for 3 weeks. Nine of these 12 teeth were each assigned to 1 of 9 different combinations of brushing force (0.98, 1.96, or 2.45 N) and duration (10, 20, or 40 seconds). The remaining 3 teeth received plaque removal without brushing, via a scaler. RESULTS: Force and duration of toothbrushing affected both proliferating cell nuclear antigen (PCNA)-positive and procollagen Type I C-peptide (PIP)-positive fibroblast ratios (P < 0.05). The highest ratio of PCNA-positive fibroblasts was produced by brushing at 1.96 N for 20 seconds. The highest ratio of PIP-positive fibroblasts was produced by brushing at 1.96 N for 10 seconds. CONCLUSIONS: Toothbrushing at certain forces and durations enhanced the proliferative activity and procollagen synthesis of gingival fibroblasts. The toothbrushing duration that increased procollagen synthesis (10 seconds) was shorter than that which increased fibroblast proliferative activity (20 seconds).

Toothbrushing promotes gingival fibroblast proliferation more effectively than removal of dental plaque.

OBJECTIVES: Removal of dental plaque is an essential element of periodontal treatment. However, there have also been studies of the effects of the mechanical stimulation provided by toothbrushing on gingival host-defense mechanisms. The aim of the study was to evaluate the effects of toothbrushing on gingival fibroblast proliferation in dogs over time, compared to effects of plaque removal without brushing. METHODS: The mouths of six mongrel dogs were divided into four quadrants: two for daily toothbrushing, and two for daily plaque removal with a curette. After 1, 3 and 5 weeks of treatment, histometrical analyses were performed to assess inflammatory cell infiltration, proliferating cell nuclear antigen (PCNA)-positive fibroblasts, procollagen type I-positive fibroblasts in the subepithelial connective tissue of junctional epithelium. RESULTS: Toothbrushing increased the number of PCNA-positive fibroblasts in the first week, increased the number of type I procollagen-positive fibroblasts at the fifth week, and reduced inflammatory cell infiltration at the third week. CONCLUSION: These findings suggest that mechanically stimulated fibroblasts begin proliferating within a week, and this cell division results in an increased number of fibroblasts at the third week. It takes 5 weeks before differences in collagen synthesis between brushing and plaque removal areas are detectable.

The effect of duration and force of mechanical toothbrushing stimulation on proliferative activity of the junctional epithelium.

BACKGROUND: Gingival bleeding is frequently accompanied by an ulcerated epithelium, with repair depending on the proliferative activity of the epithelial cells. The present study examined the proliferative activity of the junctional epithelium (JE) under several different methods of toothbrushing stimulation. METHODS: Twelve dogs were used in this 3-week experiment. Prior to the experiment, all teeth underwent daily removal of plaque and calculus using a scaler. Teeth were then divided into quadrants: 9 teeth in 3 quadrants (test, 3 per quadrant) were mechanically stimulated by toothbrushing for various time intervals (10, 20, or 40 seconds) and at various forces (100, 200, or 250 gf). The 3 teeth in the fourth quadrant served as controls. The proliferative activity of the basal cells of the junctional epithelium was evaluated for expression of proliferating cell nuclear antigen (PCNA). The numbers of PCNA-positive basal cells and total basal cells were counted, and the width of the junctional epithelium was measured. RESULTS: Toothbrushing force significantly affected the PCNA-positive basal cell ratio (P < 0.05). The 200 g toothbrushing force produced the highest PCNA-positive basal cell ratio, which was significantly higher than that using the 100 g force (P < 0.05). CONCLUSION: In junctional epithelium stimulated with a toothbrush, the PCNA-positive basal cell ratio is more sensitive to toothbrushing force than to duration.