Gingival condition and tooth-brushing behavior after alcohol consumption.

BACKGROUND AND OBJECTIVE: Various studies have reported the relationship between alcohol consumption and gingival condition. However, they focus on the direct effects of alcohol consumption or alcohol sensitivity on gingival condition, and it is unclear how oral health behaviors relate these relationships. The aims of this study were to assess the inter-relationships between gingival condition, tooth-brushing behavior after drinking alcohol and alcohol sensitivity in university students who drink more than once per week on average. MATERIAL AND METHODS: A total of 808 students (541 males, 267 females) that habitually consume alcohol were analyzed. The disease activity of gingival condition was assessed as the percentage of bleeding on probing (%BOP). Additional information regarding alcohol sensitivity and oral health behaviors, including tooth-brushing behavior after drinking, were also collected. RESULTS: Thirteen percent of the current participants reported neglecting tooth-brushing after drinking, and their alcohol consumption was higher than those who did not neglect tooth-brushing. Logistic regression analysis showed that high %BOP (%BOP ≥ 20) was associated with male (OR = 1.53; 95% CI, 1.01-2.33), neglect of tooth-brushing after drinking (OR = 2.60; 95% CI, 1.20-5.61) and debris index (OR = 8.38; 95% CI, 4.24-16.60) in participants with low alcohol sensitivity. In participants with high alcohol sensitivity, high %BOP was associated with debris index (OR = 7.60; 95% CI, 3.12-18.51), but not with any oral health behaviors. CONCLUSIONS: The study revealed that alcohol consumption was indirectly related to gingival disease activity through the neglect of tooth-brushing after drinking alcohol in university students with low alcohol sensitivity.

Relationship between xerostomia and gingival condition in young adults.

BACKGROUND AND OBJECTIVE: Xerostomia is a subjective symptom of dryness in the mouth. Although a correlation between xerostomia and oral conditions in the elderly has been reported, there are few such studies in the young adults. The aim of this study was to examine the relationship of xerostomia with the gingival condition in university students. MATERIAL AND METHODS: A total of 2077 students (1202 male subjects and 875 female subjects), 18-24 years of age, were examined. The disease activity and severity of the gingival condition were assessed as the percentage of teeth with bleeding on probing (%BOP) and the presence of teeth with probing pocket depth of ≥ 4 mm, respectively. Additional information on xerostomia, oral health behaviors, coffee/tea intake and nasal congestion was collected via a questionnaire. Path analysis was used to test pathways from xerostomia to the gingival condition. RESULTS: One-hundred and eighty-three (8.8%) students responded that their mouths frequently or always felt dry. Xerostomia was related to %BOP and dental plaque formation, but was not related to the presence of probing pocket depth ≥ 4 mm. In the structural model, xerostomia was related to dental plaque formation (p < 0.01), and a lower level of dental plaque formation was associated with a lower %BOP. Xerostomia was associated with coffee/tea intake (p < 0.01) and nasal congestion (p < 0.001). CONCLUSION: Xerostomia was indirectly related to gingival disease activity through the accumulation of dental plaque. Nasal congestion and coffee/tea intake also affected xerostomia. These findings suggest that xerostomia should be considered in screening for gingivitis risk in young adults.

Effects of electrical stimulation on periodontal tissue remodeling in rats.

BACKGROUND AND OBJECTIVE: Electric current is used to promote wound healing. However, it is unclear whether electrical stimulation contributes to gingival tissue remodeling. This study examined the effects of electrical stimulation on gingival tissue remodeling in a rat periodontitis model. MATERIAL AND METHODS: Male Wistar rats (n = 28, 8 wks of age) were divided into four groups of seven rats each. The control group did not receive any treatment for 6 wks. In the other groups, periodontitis was ligature-induced for 4 wks. After 4 wks, the rats with periodontitis were given daily electrical stimulation of 0, 50 or 100 µA for 2 wks. RESULTS: The periodontitis group stimulated with 0 µA showed a higher density of polymorphonuclear leukocytes and a lower density of collagen in gingival tissue compared with the control group (p < 0.05). The two remaining groups treated with 50 or 100 µA of electrical stimulation exhibited a lower density of polymorphonuclear leukocytes (p < 0.05) and a higher density of collagen than the group stimulated with 0 µA (p < 0.05). They also showed higher expression of fibroblast growth factor-2 than the group treated with 0 µA of electrical stimulation (p < 0.05). CONCLUSION: Electric stimulation may offer a novel approach to promote gingival tissue remodeling in periodontal lesions.

Effects of topical application of inorganic polyphosphate on tissue remodeling in rat inflamed gingiva.

BACKGROUND AND OBJECTIVE: Inorganic polyphosphate [poly(P)] is a biopolymer found in almost all cells and tissues, and which promotes tissue remodeling. However, there is limited information on how poly(P) affects the connective tissue in inflamed gingiva. This study examined the effects of topical application of poly(P) on gingival connective tissue and its remodeling in a rat periodontitis model. MATERIAL AND METHODS: Male Wistar rats (n = 36, 8 wk of age) were used in this 6-wk study. The rats were divided into six groups of six rats each. The control group received no treatment. In the other groups, periodontitis was ligature-induced for 4 wk. After 4 wk, the rats with periodontitis were further divided into five groups, and were left untreated (periodontitis group) or subjected to topical application of oral rinses containing 0, 0.1, 1 or 5% poly(P) for 2 wk. RESULTS: The periodontitis and 0% poly(P) groups showed a higher density of polymorphonuclear leukocytes and a lower density of collagen in gingival tissue than the control group (p < 0.05). In contrast, groups treated with more than 1% poly(P) exhibited a lower density of polymorphonuclear leukocytes (p < 0.05) and a higher density of collagen than the periodontitis and 0% poly(P) groups (p < 0.05). A higher expression of fibroblast growth factor-2 was observed in the gingiva of rats treated with 1% poly(P) than in those treated with 0% poly(P) (p < 0.05). CONCLUSION: Topical application of poly(P) may induce connective tissue remodeling, contributing to improvement of inflamed gingiva in rats.

Loss of claudin-1 in lipopolysaccharide-treated periodontal epithelium.

BACKGROUND AND OBJECTIVE: The epithelial barrier is a critical component of innate immunity and provides protection against microbial invasion. Claudin-1, a tight junction protein, is known to contribute to the epithelial cell barrier. An experimentally induced rat periodontal disease model was used to study the effects of lipopolysaccharide (LPS) on the expression of tight junction-associated molecule genes in the junctional epithelium. MATERIAL AND METHODS: LPS was applied for 8 wk in the gingival sulcus, and junctional epithelium was collected by laser-capture microdissection and subjected to microarray analysis. RESULTS: Microarray analysis identified that expression of the claudin-1 gene was decreased in the epithelium by chronic LPS challenge. Immunohistochemical analysis confirmed the expression of claudin-1 protein in junctional epithelium and that 8 wk of chronic LPS topical application significantly reduced claudin-1 expression. The effect of LPS on claudin-1 protein expression was validated using a porcine junctional epithelial cell culture Transwell model. The epithelial barrier, as measured using transmembrane resistance, was significantly reduced after 3 wk of LPS challenge and this was associated with a decreased level of expression of claudin-1 protein. CONCLUSION: These results confirm that the initiation of experimental periodontal disease is associated with reduction in the expression of claudin-1 gene and protein. This decreased level of a critical tight junction protein may result in the disruption of barrier function and may play an important role in the initiation of periodontal disease.

Relationship between the prognosis of periodontitis and occlusal force during the maintenance phase--a cohort study.

BACKGROUND AND OBJECTIVE: Few studies have longitudinally investigated the relationship between periodontal disease progression and occlusal factors in individual subjects during the maintenance phase of periodontal therapy. The aim of this cohort study was to investigate the relationship between biting ability and the progression of periodontal disease in the maintenance phase. MATERIAL AND METHODS: A total of 194 patients were monitored for 3 years during the maintenance phase of periodontal therapy. The subjects with disease progression (Progress group) were defined based on the presence of >or= 2 teeth demonstrating a longitudinal loss of proximal attachment of >or= 3 mm or tooth-loss experience as a result of periodontal disease during the study period. The subjects with high occlusal force were diagnosed as men who showed an occlusal force of more than 500 N and women who showed an occlusal force of more than 370 N. The association between biting ability and the progression of periodontitis was investigated using logistic regression analysis. RESULTS: There were 83 subjects in the Progress group and 111 subjects in the Non-progress group. A backward, stepwise logistic regression model showed that the progression of periodontal disease was significantly associated with the presence of one or more teeth with a high clinical attachment level (CAL) of >or= 7 mm (odds ratio: 2.397; 95% confidence interval: 1.306-4.399) ( p = 0.005) and low occlusal force (odds ratio: 2.352; 95% confidence interval: 1.273-4.346) ( p = 0.006). CONCLUSION: The presence of one or more teeth with a high CAL of >or= 7 mm and low occlusal force might be possible risk factors for periodontal progression in the maintenance phase of periodontal therapy.

Effects of topical application of lipopolysaccharide and proteases on hepatic injury induced by high-cholesterol diet in rats.

BACKGROUND AND OBJECTIVE: Topical application of lipopolysaccharide and proteases to the gingival sulcus induced not only periodontal inflammation but also detectable liver changes in rats fed a normal diet. However, these changes in the liver were not sufficient to induce pathological consequences. The purpose of the present study was to investigate whether gingival inflammation-induced liver change would have more dramatic pathological consequences in rats fed a high-cholesterol diet compared with the effect of the high-cholesterol diet alone. MATERIAL AND METHODS: Twenty-four male Wistar rats were divided into four groups. During an 8 week experimental period, two groups were fed a normal diet and the other two were fed a high-cholesterol diet containing 1% cholesterol (w/w) and 0.5% cholic acid (w/w). Four weeks prior to the end of the experimental period, one of each of the dietary groups received daily topical application of lipopolysaccharide and proteases to the gingival sulcus, while the other was treated with pyrogen-free water. RESULTS: In the rats without application of lipopolysaccharide and proteases, the serum level of hexanoyl-lysine, scores of steatosis and inflammation, and concentration of 8-hydroxydeoxyguanosine in liver of rats fed a high-cholesterol diet were higher than in those fed a normal diet. In rats fed a high-cholesterol diet, the scores of steatosis and inflammation and the concentration of 8-hydroxydeoxyguanosine in the liver of rats with application of lipopolysaccharide and proteases were higher than in those without. CONCLUSION: In a rat model, application of lipopolysaccharide and proteases to the gingival sulcus augmented the effect of a high-cholesterol diet on steatosis, inflammation and oxidative damage in the liver.

Effects of mechanical stimulation by a powered toothbrush on the healing of periodontal tissue in a rat model of periodontal disease.

BACKGROUND AND OBJECTIVE: Elimination of pathogens is the main aim of periodontal treatment; however, modulation of the host immune response should also be considered. This study aimed to evaluate the effects of mechanical stimulation on periodontal healing in rats. MATERIAL AND METHODS: Before starting the experiment, lipopolysaccharide and proteases were applied once a day, for 4 wk, to both maxillary first molars of 30 rats to induce periodontal disease, and the application was stopped at the end of the 4-wk period. The experiment started immediately following this pretreatment. In the experiment, the left palatal gingiva was stimulated once daily using a powered toothbrush and the right gingiva served as a control (no mechanical stimulation). Pathological changes, and proliferation and cell death in periodontal tissues, were evaluated histometrically and immunohistochemically at baseline (0 wk), and at 1 and 3 wk of stimulation. RESULTS: The control showed a reduction of polymorphonuclear leukocyte infiltration in connective tissue and an increase in the numbers of gingival and periodontal ligament fibroblasts. Mechanical stimulation reduced polymorphonuclear leukocyte infiltration and the area of destroyed collagen in connective tissue, and increased the number of gingival fibroblasts; however, it had no effect on alveolar bone and root resorption or on the number of periodontal ligament fibroblasts. CONCLUSION: Mechanical stimulation accelerated the healing of gingival inflammation by reducing the infiltration of polymorphonuclear leukocytes and enhancing fibroblast proliferation and collagen synthesis.

Relationship between periodontal condition and arterial properties in an adult population in Japan.

UNLABELLED: Oral Diseases (2010) 16, 781-787 OBJECTIVE: This study addressed the relationship between periodontal condition and second derivative of the finger photoplethysmogram (SDPTG) in Japanese adults. SUBJECT AND METHODS: The Community Periodontal Index (CPI) and SDPTG were recorded in 415 subjects (mean age: 44.0 years). For assessing SDPTG, we mainly focused on the ratio of the absolute value of the height of the early negative 'b' wave and ratio of the late re-decreasing 'd' wave to the height of the initial positive 'a' wave, namely the b/a and d/a ratios. RESULTS: The CPI score was positively correlated with the b/a ratio (P < 0.001), and negatively correlated with the d/a ratio (P < 0.001). Logistic regression analysis showed that subjects with CPI scores ≥ 3 were more likely to have a higher level (male > -0.69, female > -0.64) of b/a ratio (Odds ratio = 1.7, P = 0.026) and lower level (male ≤ -0.29, female ≤ -0.32) of d/a ratio (Odds ratio = 2.2, P =0.001) than those with CPI scores 0-2, after adjusting for age, gender, smoking status, pulse rate and presence of hypertension. CONCLUSION: There was a statistical association between the CPI scores and SDPTG indices in Japanese adults.

Periodontitis-induced lipid peroxidation in rat descending aorta is involved in the initiation of atherosclerosis.

BACKGROUND AND OBJECTIVE: Periodontitis is a risk factor for the development of atherosclerosis. Recent studies indicate that oxidative mechanisms, including lipid peroxidation, are involved not only in periodontitis but also in atherosclerosis. Lipid peroxidation may play an important role in the pathogenesis of atherosclerosis, particularly during its earliest stages. The purpose of this study was to investigate the relationship between lipid peroxidation induced by periodontitis and the initiation of atherosclerosis. MATERIAL AND METHODS: Sixteen rats were randomly divided into two groups of eight rats each. Periodontitis was ligature-induced for 4 wk in the experimental group, whereas the control group was left untreated. After the experimental period, the mandibular first molar regions were resected and then subjected to histological analysis and measurement of hexanoyl-lysine expression as an indicator of lipid peroxidation. Descending aorta was used for measuring the levels of hexanoyl-lysine, reactive oxygen species and lipid deposits, and for real-time polymerase chain reaction microarray analysis. The level of hexanoyl-lysine was also measured in serum. RESULTS: In the experimental group, the levels of hexanoyl-lysine in periodontal tissue and serum increased. Only aorta samples in the experimental group showed lipid accumulation, with increased expression of hexanoyl-lysine, reactive oxygen species and oxidative stress-related genes (including nitric oxide synthases 2 and 3), whereas the superoxide dismutase 1 gene level was down-regulated. CONCLUSION: In a ligature-induced periodontitis rat model, increased lipid peroxidation was found in serum and aorta as well as in periodontal tissue. Atherosclerosis-related gene expression and histological changes were also stimulated. Periodontitis-induced lipid peroxidation in the aorta may be involved in the early stage of atherosclerosis.

Relation of dietary preference to bite force and occlusal contact area in Japanese children.

The purpose of this study was to examine the relationship of dietary preference to bite force and occlusal contact area in Japanese elementary school children. A total of 348 children, aged 7-12 years, from two public elementary schools located in Okayama Prefecture, Japan, participated in the study. Clinical examination included decayed, missing and filled teeth (dmft and DMFT), and total numbers of deciduous and permanent teeth. Bite force and occlusal contact area were measured using a pressure-detecting sheet. Dietary preference was assessed using a questionnaire in which the answers were given in like/dislike form. Mann-Whitney U-test and multiple logistic regression analysis were applied to analyse the data. In multiple logistic regression analysis after adjustment for age, gender and total number of teeth present, children who liked cabbage and celery showed significantly higher bite force (P = 0.05 and P < 0.01, respectively) than those who disliked these. Children who liked cabbage and celery also showed higher occlusal contact area (P < 0.05 and P < 0.01, respectively) than those who disliked these. The Japanese elementary school children who liked hard foods such as cabbage and celery showed higher bite force and higher occlusal contact area than those who disliked these foods. A positive attitude towards harder food items might contribute to healthy development of the masticatory apparatus.

Effects of ethanol consumption on periodontal inflammation in rats.

Studies suggest a correlation between ethanol consumption and periodontal disease. We hypothesized that elevated levels of blood reactive oxygen species following ethanol consumption may increase inflammation in periodontal tissue. Rats were divided into 4 groups (6-7 rats/group). Two groups were fed an ethanol-containing liquid diet, and 2 groups were fed a pair-fed control diet. In one of each dietary group, periodontitis was ligature-induced, while the other group was left unligated. Chronic ethanol feeding alone decreased the ratio of reduced/oxidized glutathione and increased 8-hydroxydeoxy-guanosine and tumor necrosis factor (TNF)-alpha levels in the gingiva. Blood hydroperoxides were also increased. In ligature-induced periodontitis lesions, ethanol feeding enhanced polymorpho-nuclear leukocyte infiltration and TNF-alpha expression. The results suggest that chronic alcohol consumption increased periodontal inflammation, oxidative damage, and TNF-alpha production and had an additive effect on polymorphonuclear leukocyte infiltration and gingival oxidative damage, increasing the severity of periodontal inflammation in the ligature model.

Relationship between body mass index and periodontitis in young Japanese adults.

BACKGROUND AND OBJECTIVE: Obesity has been implicated as a risk factor for several chronic health conditions. Recent studies have reported a relationship between obesity and periodontitis, but few studies have investigated this relationship in adolescents. The purpose of the present study was to investigate the relationship between body composition (i.e. body mass index and body fat) and periodontitis in university students in Japan. MATERIAL AND METHODS: Medical and oral health data were collected in a cross-sectional examination conducted by the Health and Environment Center of Okayama University. Students aged 18-24 years (n = 618), who were interested in receiving an oral health examination, were included in the analysis. The community periodontal index was used to assess periodontal status. Subjects with a community periodontal index score of 0-2 were considered as controls and those with a community periodontal index score of > 2 were considered to have periodontitis. Logistic regression analysis was used to estimate the association between body mass index and periodontitis. RESULTS: The body mass index of all subjects was < 30 kg/m2. Age and body mass index were significantly associated with the community periodontal index. Logistic regression analysis revealed a 16% increased risk for periodontitis per 1-kg/m2 increase in body mass index (adjusted odds ratio, 1.16; 95% confidence interval, 1.03-1.31; p < 0.05). CONCLUSION: Body mass index could be a potential risk factor for periodontitis among healthy young individuals (i.e. those with a body mass index of < 30 kg/m2). It may be useful to include an evaluation of body mass index on a regular basis in university general and oral health examinations.

Effects of a high-cholesterol diet on cell behavior in rat periodontitis.

Studies have shown an association between periodontitis and serum cholesterol levels. We hypothesized that high dietary cholesterol could influence periodontitis as a result of proliferation of the junctional epithelium. Rats were divided into 4 groups. Two groups were fed a regular diet, and 2 groups were fed a high-cholesterol diet. One of each dietary group was treated with periodontitis-inducing agents (lipopolysaccharide and proteases), while the other was treated with pyrogen-free water. Feeding rats with a high-cholesterol diet induced an increase in blood total cholesterol and a decrease in high-density lipoprotein cholesterol. Proliferation of the junctional epithelium with increasing bone resorption was promoted by the consumption of a high-cholesterol diet. High dietary cholesterol further increased the cell-proliferative activity of the junctional epithelium induced by lipopolysaccharide and proteases. These results suggest that high dietary cholesterol can initiate and augment periodontitis in the rat periodontitis model.

Anti-aging effects of co-enzyme Q10 on periodontal tissues.

Oxidative stress is associated with age-related reactions. The anti-oxidative effects of a reduced form of co-enzyme Q10 (rCoQ10) suppress oxidative stress, which may contribute to the prevention of age-related inflammatory reactions. We examined the effects of topically applied rCoQ10 on periodontal inflammatory reactions in a rat aging model. Male Fischer 344 rats, 2 (n = 6) and 4 mos (n = 18) of age, were used. All of the two-month-old rats and 6 of the four-month-old rats were sacrificed and 12 remaining four-month-old rats received topically applied ointment with or without 1% rCoQ10 on the gingival surface until they reached 6 mos of age. The rats showed an age-dependent increase in circulating oxidative stress. RCoQ10 decreased oxidative DNA damage and tartrate-resistant acid-phosphatase-positive osteoclasts in the periodontal tissue at 6 mos of age as compared with the control. The same conditions lowered gene expression of caspase-1 and interleukin-1ß in the periodontal tissue. Furthermore, Nod-like receptor protein 3 inflammasomes were less activated in periodontal tissues from rCoQ10-treated rats as compared with the control rats. Our results suggest that rCoQ10 suppresses age-related inflammatory reactions and osteoclast differentiation by inhibiting oxidative stress.

Relationship between malocclusion and heart rate variability indices in young adults: a pilot study.

OBJECTIVES: Heart rate variability (HRV) has been used to assess sympathetic and parasympathetic modulation of heart rate. Chronic stress relates to reduced HRV. Malocclusion has effects on quality of life, which can lead to chronic stress. Therefore, we hypothesized that malocclusion, as chronic stress, may contribute to reduced HRV. The aim of this study was to investigate the relationship between malocclusion and HRV indices in healthy young adults. METHODS: Thirty-seven non-smoking healthy subjects, aged 22 to 25 years, were examined. Malocclusion was defined by Angle classification. HRV indices included root mean square of successive differences, low frequency (LF), high frequency (HF) and ratio of LF to HF. The effects of malocclusion on quality of life and mental health were assessed using self-reported questionnaires, the condition-specific Oral Impacts on Daily Performances index (CS-OIDP) and the Hopkins Symptoms Checklist (HSCL), respectively. RESULTS: Significantly lower score of HF and higher heart rate (HR) level and CS-OIDP score were observed in subjects with malocclusion (n = 17) compared to those in the control subjects (n = 20) ( P <0.05). There was a positive correlation between HR and score of "anxiety" in HSCL ( P <0.05). CONCLUSIONS: The data showed an association between malocclusion and lower HRV. Based on our results, orthodontic treatment might contribute not only to improvement of oral esthetic and functional problems but also to improvement of stress and HRV indices.

Occlusal disharmony increases amyloid-ß in the rat hippocampus.

Amyloid-ß plays a causative role in Alzheimer's disease. Occlusal disharmony causes chronic psychological stress, and psychological stress increases amyloid-ß accumulation. The purpose of the present study was to investigate whether occlusal disharmony-induced psychological stress affects the accumulation of amyloid-ß and its related gene expressions in the rat hippocampus. Eight-week-old male Wistar rats (n = 18) were divided into three groups of six rats each: (1) a control group that received no treatment for 8 weeks; (2) an occlusal disharmony group that underwent cutoff maxillary molar cusps for 8 weeks; and (3) a recovered group that underwent cutoff maxillary molar cusps for 4 weeks followed by recovery for 4 weeks. Occlusal disharmony increased plasma corticosterone levels in a time-dependent manner. Levels of amyloid-ß 40 and 42, glucocorticoid receptor (Gr) protein, and cleaved caspase 3 (Casp3) as well as gene expressions of amyloid precursor protein, beta-secretase, Casp3, and Gr in the hippocampus in the occlusal disharmony group were significantly higher than those in the control group (P < 0.016). These findings were significantly improved by recovery of occlusion (P < 0.016). These results indicate that psychological stress induced by occlusal disharmony reversibly induces amyloid-ß 40 and 42 in the rat hippocampus through the glucocorticoid signal.

Location of proliferating gingival cells following toothbrushing stimulation.

OBJECTIVES: Mechanical stimulation by toothbrushing promotes healing of gingivitis through accelerating cell proliferation. Junctional epithelium proliferates at periodontal pocket formation. A question is arisen whether toothbrushing contributes to the repair of gingival inflammation or deterioration of pocket formation. The location of proliferating cells in gingiva stimulated mechanically by toothbrushing was investigated. MATERIALS AND METHODS: A total of 24 teeth of dogs underwent daily plaque removal with a curette (plaque removal) or both plaque removal and toothbrushing (toothbrushing). Proliferative activity of gingival cells in six individual zones was evaluated by assaying expression of proliferating cell nuclear antigen (PCNA). RESULTS: Toothbrushing increased densities of PCNA-positive basal cells in the junctional epithelium, connective tissues adjacent to the junctional epithelium, the alveolar bone of the oral epithelial side and the oral epithelium. However, the densities of PCNA-positive cells at the apical portion of the junctional epithelium, connective tissues adjacent to the cementum and the alveolar bone of the periodontal ligament side did not increase following toothbrushing. CONCLUSIONS: Toothbrushing promotes proliferation of gingival cells other than fibroblasts in periodontium and basal cells in the apical portion of the junctional epithelium. The repair of periodontal tissues might be promoted by toothbrushing within the limit of the direct mechanical stimulation.

Regulation of epithelial cell growth factor receptor protein and gene expression using a rat periodontitis model.

BACKGROUND AND OBJECTIVE: Regulation of epithelial cell behavior associated with periodontitis is not well elucidated but many responses will ultimately be regulated by growth factor receptors. Using a rat experimental periodontitis model, protein and gene expression of select growth factor receptors in junctional and pocket epithelium were examined. MATERIAL AND METHODS: Periodontal disease was induced by daily topical application of lipopolysaccharide using an established protocol. Animals were killed at time 0 (control), and at 2 and 8 wk. Frozen tissue samples were collected from the right palatal gingival soft tissue, and the left periodontal tissues were decalcified and embedded in paraffin. Laser microdissection and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to quantify keratinocyte growth factor receptor (KGFR), hepatocyte growth factor receptor (HGFR), epidermal growth factor receptor (EGFR) and fibroblast growth factor receptor 1 (FGFR1) gene expression, and in situ RT-PCR localized these increases to specific epithelial cells. Receptor protein expression was examined immunohistochemically. In cell culture, induction of HGFR and KGFR protein expression by serum, lipopolysaccharide and pro-inflammatory cytokines were examined using flow cytometry. RESULTS: Eight-week tissue samples exhibited histological changes consistent with periodontitis. KGFR and HGFR gene and protein expression were significantly induced at the 8 wk time point. KGFR expression was significantly up-regulated in basal and parabasal pocket epithelial cells, but HGFR was up-regulated throughout the pocket epithelium. In cell culture serum, lipopolysaccharide and pro-inflammatory cytokines, interleukin-1beta and tumour necrosis factor-alpha significantly induced KGFR protein receptor expression, but HGFR expression was only induced by serum. CONCLUSION: KGFR and HGFR are highly up-regulated in this model of periodontal disease and may play a significant role in regulating the proliferation and migration of pocket epithelium.

Proteases augment the effects of lipopolysaccharide in rat gingiva.

OBJECTIVES: Lipopolysaccharide (LPS) and proteases have been implicated as important factors in the initiation and progression of human periodontal diseases. A single application of LPS or proteases is insufficient to induce periodontal pocket formation or periodontitis. The aim of the present study was to assess the combined effect of lipopolysaccharide and proteases on rat periodontal tissues, and create a periodontal disease model. MATERIALS AND METHODS: Forty male Wistar rats were divided into four groups: combination group (treated with both LPS and proteases solutions); LPS group; proteases group; and control. Each solution was introduced daily into the palatal gingival sulcus of maxillary molars for 8 weeks. The tissues were evaluated histometrically and immunohistochemically. RESULTS: In the LPS group, elongation of rete ridge, apical migration of junctional epithelium (JE), increased numbers of B cells in connective tissue, and resorption of alveolar bone were observed. In the proteases group, the increase in the number of infiltrating polymorphonuclear leukocytes and blood vessels in the connective tissue was greater than that of the LPS group. CONCLUSIONS: The effects of LPS on periodontal tissues differed from those of proteases. The addition of proteases augmented and increased the effects of LPS, which were apical migration, intraepithelial cleavage of JE, and increased B cell density. The lesions in the combination group resembled established lesions of human periodontitis, with the exception of the low density of plasma cells.