Influence of age and immunization on development of gingivitis in rats

Platelet rich fibrin versus ozone gel for periodontal regeneration in induced rats' intrabony three-wall periodontal defects

BACKGROUND

The question of whether platelet rich fibrin and ozone can enhance regeneration of periodontal defect was addressed.

MATERIALS AND METHODS

three-wall periodontal defects were surgically created in 30 rats involving mesial aspect of right mandibular first molar. Rats were randomly assigned into three groups: 1) Group I (Positive control group). 2) Group II (Ozone treated group) and 3) Group III (PRF treated group). Two weeks after surgery, five rats from each group were euthanized and the remaining was euthanized 4 weeks post surgery. The degree of periodontal regeneration was evaluated using light microscope and scanning electron microscope. Histomorphometric measurements and anti-PCNA immunohistochemical counting were statistically analyzed.

RESULTS

group I showed intense inflammatory reaction with mild new bone formation. In group II, partial regeneration was seen with moderate new woven bone formation in 2 weeks period. After 4 weeks, almost complete restoration of periodontium was seen. In group III, after 2 weeks, moderate lamellar bone formation was observed. In 4 weeks period, the periodontal regeneration was almost completed. Histomorphometric analysis showed a significant difference between group I and group II. The difference between group I and group III was significant in 2 weeks and highly significant after 4 weeks. That between group II and group III was nonsignificant in 2 weeks and significant in 4 weeks. Anti-PCNA analysis was nonsignificant between groups.

CONCLUSIONS

both Platelet rich fibrin and ozone can improve histological parameters associated with healing of experimental intrabony periodontal defects in rats with the former being superior.

Transient effect of a short-term educational programme without prophylaxis on control of plaque and gingival inflammation in school children

The development of chronic inflammatory periodontal diseases is strongly correlated with the growth and maturation of subgingival bacterial colonies. Consequently a major preventive goal should be the control of plaque formation. We conducted a randomized, controlled trial to examine the short-term effect of an intensive instructional program without professional prophylaxis on the gingival health of 240, 11-14 year old school children. Plaque index (PlI), gingival index (GI), bleeding index (BI) and probing pocket depth (PD) were examined 4 x by 1 examiner blinded to the instruction. During the period of instruction, subjects in the experimental groups were involved in a plaque and gingivitis prevention program provided in separate educational sessions. One of the experimental groups (E-1; n = 80) was provided with a new toothbrush, toothpaste and instruction while the second experimental group (E-2; n = 80) was provided with toothbrush, toothpaste, dental floss and instruction. In the control group (C; n = 80) only dental examinations were provided: no preventive program or oral health measures were conducted. Examinations were conducted every 3 months during the instructional period and at 6 months following the completion of the active preventive programme. During the experimental period there was a significant decrease (p < 0.001) in the mean PlI, GI and BI of the experimental groups following the program while in controls there was a slight but not significant increase of mean values (p > 0.05). During the preventive program experimental groups exhibited small but not significant (p > 0.05) reductions of PD. Experimental group 1 showed similar PlI, GI, BI and PD scores as experimental group 2 during the study. After the instructional program was completed and a period of 6 months had passed, there was a large and significant (p < 0.001) increase of mean PlI, GI and BI scores in both experimental groups back to the baseline levels. We conclude that a short-term preventative program without professional instrumentation induces a transient improvement of gingival health of schoolchildren but only during the instructional period. The maintenance of improved gingival health over longer time periods requires prolonged, repeated instruction by professionals. These measures may be difficult to institute and are of questionable cost-effectiveness.

Microbiological and immunological aspects of experimental periodontal disease in rats: a review article

Animal models in which microbiological and immunological aspects of periodontal disease can be studied prospectively seem well warranted. The rat bears much resemblance to man with respect to periodontal anatomy, development and composition of dental plaque, histopathology of periodontal lesions, and basic immunobiology. Furthermore, reproducible methods are available for assessment of periodontal disease in rats, and detectable periodontal destruction can be induced in a few weeks in these animals without traumatizing periodontal tissues with ligatures. Experimental periodontitis studies in germ-free rats have confirmed the pathogenicity of several suspected periodontal pathogens (Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Capnocytophaga sputigena, Eikenella corrodens, and Fusobacterium nucleatum). The studies also suggest that the number of periodontal pathogens may be higher than generally believed, since species like Streptococcus sobrinus and Actinomyces viscosus are associated with periodontal bone loss in rats. Studies in rats with congenital or induced immune defects indicate that generalized or selective immunosuppression at the time of infection with periodontal pathogens may aggravate periodontal disease. Studies in immunized rats indicate that periodontal disease can be prevented by immunization against periodontal pathogens. However, it is also possible by immunization to induce periodontal destruction; i.e., the immune system has a destructive potential which should not be overlooked. In the future, the rat model may prove valuable for initial screening of antigen preparations and immunization regimens in the search for a periodontitis vaccine.