The purpose of this study was to compare histologic and morphometric procedures of bone height measurement. Microscopic measurements are the most frequent methods in periodontal studies with animals, but have limited capacity to identify bone levels associated with both healthy tissues and periodontal disease. Ligatures were placed in the maxillary left second molars of 10 male 60-day-old Wistar rats for 30 days. Left and right maxillary sides of 5 rats were processed for histologic analysis (H), sectioned buccolingually, and stained with HE. The maxillae of the other 5 rats were defleshed and used for morphometric analysis (M). Histometric measurements from the cementoenamel junction to the bone crest were performed. Standardized photographs were used for morphometric analysis. The t test was used for dependent or independent samples (alpha = 0.05%). Distances from cementoenamel junction to bone crest were 0.95 +/- 0.25 and 1.07 +/- 0.30 mm for H and M, respectively. Buccal measurements were 0.92 +/- 0.16 and 1.08 +/- 0.35 mm for H and M. The values obtained using H and M for areas without ligatures were 0.44 +/- 0.15 and 0.47 +/- 0.11 mm for lingual measurements and 0.23 +/- 0.08 and 0.41 +/- 0.10 mm for buccal measurements. No significant differences were found between the two methods in the detection of bone height associated with the placement of ligatures in rats.

In recent years, different chlorhexidine formulations have been tested, including an alcohol-free alternative, but the effect of this solution on early biofilm formation is not clear. A crossover, randomized, double-blind clinical trial was conducted to evaluate the effect of two chlorhexidine solutions against supra-and subgingival biofilm formation (NCT#02656251). Thirty-five participants were randomized and asked to rinse twice daily with 15 ml of an alcohol-containing 0.12% chlorhexidine solution, an alcohol-free 0.12% chlorhexidine solution, or placebo. The study was conducted in three experimental periods of 4 days each, with a 10-day washout between the periods. All the experimental periods followed the same protocol, except that the solutions were switched. Biofilm distribution was evaluated every 24 hours by the Plaque-Free Zone Index, during 96 hours. Adverse events were self-reported and sensory evaluation was performed using a hedonic scale. Compared to the placebo, the chlorhexidine solutions resulted in a significantly higher number of surfaces free of plaque over 96 hours (p < 0.01), and were able to prevent subgingival biofilm formation (p < 0.01). The alcohol-free chlorhexidine solution was associated with a lower incidence of adverse events, compared with alcohol-containing chlorhexidine (p < 0.05); it also received better sensory evaluation and acceptance by trial participants, compared with the alcohol-containing chlorhexidine (p = 0.007), and had a similar inhibitory effect on the formation of supra-and subgingival biofilms.

Nifedipine itself did not lead to gingival enlargement in rats. In the presence of biofilm accumulation, nifedipine yielded greater gingival enlargement and periodontal inflammation, but it did not increase periodontal destruction.

The rat model is widely used in periodontal research and the quality of histological sections is essential. The purpose of this study was to evaluate the histological characteristics of periodontal tissues in Wistar rat maxillae, with different times of fixation and decalcified by nitric acid or formic acid (Anna Morse Solution). Fifteen rats were used. Fixation was performed for 24, 48 and 72 hours. The maxillae were hemi-sectioned and each part was decalcified either in nitric acid for 7 days or in Anna Morse solution for 35 days. Two trained and blinded examiners performed the evaluation. Fourty eight hours of fixation and decalcification with Anna Morse solution showed more clear characteristics of the epithelium-connective tissue interface and of the periodontal structures. Mean measurements between the cementum-enamel junction and the bone crest varied in the different experimental times from 176.5 (+/- 60.45) to 210.94 (+/- 39.33) pixels on the buccal aspect, and from 199.69 (+/- 38.33) to 298.55 (+/-70.81) pixels on the palatal aspect, with no statistically significant differences (ANOVA, p > 0.05). In the same fixation period, decalcification with nitric acid or Anna Morse solution did not display any statistically significant differences. It may be concluded that for a qualitative histological analysis, fixation should preferably be for 48 hours and the demineralization should be made by Anna Morse solution. For a histomorphometric analysis, the decalcification solution does not interfere in the results.