Histologic evaluation of the effects of intrasulcular toothbrushing on human sulcular epithelium

Oral hygiene associated with antimicrobial photodynamic therapy or lingual scraper in the reduction of halitosis after 90 days follow up: A randomized, controlled, single-blinded trial

BACKGROUND

Although antimicrobial photodynamic therapy (aPDT) can reduce halitosis immediately after application, it returns after a week. This probably occurs because bacteria residing in the oral cavity may recolonize the dorsum of the tongue.

OBJECTIVE

Verify if modification of oral hygiene behavior associated with aPDT or lingual scraper can reduce halitosis after a 90-day follow-up.

METHODS

Forty adults with positive halitosis were randomized in G1 (n = 20) -aPDT + oral hygiene behavior (OHB) or G2 (n = 20)- lingual scraper + OHB. G1 group were submitted to 0.005 % methylene blue in the middle and posterior third of the tongue, with pre-irradiation of 1 min. Irradiations were performed with red laser diode (λ =660 nm), 100 mW, 318 J/cm², 3537 mW/cm², 9 J per point at 6 points. In the G2 group, the tongue was scraped 10 times on the right side and on the left side with a tongue scraper. All patients were instructed on OHB at baseline, 7 and 90 days (guidance on the use of dental floss and the Bass technique for brushing). Halitosis was evaluated by gas chromatography (OralChroma®). Values ​​> 112 ppb for Hydrogen sulfide (H₂S) gas was considered positive halitosis. Methylmercaptanes and dimethylsulfide were also measured. The gas measures were assessed at baseline, immediately, and at 7 and 90 days. Paired t-test was used for the statistical analysis. For comparison between groups, the t-test was used. Values of p < 0.05 were considered statistically significant.

RESULTS

There was no difference between groups immediately after treatment (p = .1532) after 7 days (p = 0.9312) and 90 days (p = 0.6642). For the aPDT group, there was a decrease in hydrogen sulfide ​​immediately after treatment (p = 0.0001), after 7 days, values remained 3-fold smaller (p = 0.0088) and 2-fold smaller after 90 days (p = 0.0270). For the scraper group, there was a decrease immediately after treatment (p = 0.0001), the values remains 2-fold smaller ​​(p = 0.0003) after 7 days and 3 months (p = 0.0001).

CONCLUSION

The oral hygiene behavior associated with aPDT or tongue scraper was not able to reduce halitosis after 90-day follow-up. Despite halitosis remaining ​​ higher than 112 ppb in all follow-up periods, the mean values remain 2 or 3 fold smaller than baseline values. Future studies should include other oral hygiene behavior to achieve better results in the treatment of halitosis.

PAF levels in saliva are regulated by inflammatory cells

Platelet activating factor (PAF), a powerful inflammatory phospholipid mediator, has been detected in normal human saliva and found to be increased in periodontitis. The cellular source of PAF in saliva is controversial although several data suggest an origin related to the presence of inflammatory cells. PAF levels in biological fluids are regulated by PAF-producing cells and by the PAF-degrading acetylhydrolase. Although in normal human saliva acetylhydrolase activity is very low, no information is available on the levels of this enzyme in inflammatory conditions of the mouth. The aim of our study was to assess the contribution of inflammatory cells to the levels of PAF in saliva in normal subjects and in patients with periodontitis. PAF was measured by radioimmunoassay (RIA) in mixed uncentrifuged saliva and in cell-free saliva from healthy subjects, before and after tooth brushing, and in patients with periodontitis. In healthy subjects PAF levels were significantly higher in whole saliva than in centifuged saliva (1.51 +/- 0.22 vs. 0.92 +/- 0.04 ng/ml, p < 0.0039). A significant increase in the amount of PAF was detected in whole saliva, but not in centifuged saliva, 2 h after tooth brushing. In patients with periodontitis PAF levels were not different from those of healthy individuals when using centrifuged saliva but were significantly higher when using whole, uncentrifuged saliva. Exogenous radiolabelled PAF was degraded much more rapidly by the saliva of periodontitis patients than by that of normal subjects. In conclusion, our study shows that inflammatory cells regulate the levels of PAF in saliva contributing to its production and degradation. The differential degradation of PAF in normal and inflammatory saliva highlights the absolute need of a series of methodological precautions when performing studies on salivary PAF.

The permeability of oral mucosa

In discussing permeability, we are describing one of the fundamental barrier functions of oral mucosa. Despite assumptions to the contrary, the oral mucosa is not a uniformly, highly permeable tissue like gut, but shows regional variation. The keratinized areas, such as gingiva and hard palate, are least permeable and nonkeratinized lining areas are most permeable. This variation appears to reflect differences in the types of lipid making up the intercellular permeability barrier in the superficial layers of the epithelium. Differences in permeability may be related to regional differences in the prevalence of certain mucosal diseases and can be utilized to advantage for local and systemic drug delivery.

Ultrastructural study of induced keratinization in sulcular gingival epithelium in rhesus monkeys

Gingival sulcular epithelium--which in primates normally does not keratinize--can be induced to undergo keratinization by prolonged intensive antibacterial therapy. Three months before biopsy the teeth of two adult male rhesus monkeys were scaled and polished, and for 5 days the monkeys were given intravenous injections of 75 mg Achromycin daily. Their teeth were subsequently subjected to daily cleaning and polishing. The presumably in-situ-keratinized sulcular epithelium was examined by transmission electron microscopy. It was also compared with oral gingival epithelium from the same two animals and with oral and sulcular epithelium from a rhesus monkey that had not been exposed to local or systemic antibacterial therapy. The results confirmed earlier histological studies, which have shown that under the conditions described the sulcular epithelium becomes parakeratinized. In addition, several other ultrastructural changes were observed, some of which suggest that the treatment given may result in the formation of a more efficient permeability barrier in the sulcular area. The possible clinical significance of such a barrier is briefly discussed.

The effect of mechanical stimulation on the keratinization of sulcular epithelium

This study was designed to evaluate the effect of mechanical stimulation on the keratinization of the sulcular epithelium in four adult Rhesus monkeys. Each animal received a thorough prophylaxis. One week later, each monkey received one of the following modalities of plaque control: (a) daily intravenous tetracycline and rubber cup prophylaxis, (b) daily rubber cup prophylaxis, (c) daily intravenous tetracycline injections; (d) no treatment, as a control. After sacrifice and tissue processing the histologic sections were evaluated for the presence of sulcular keratinization. The keratin width and length were measured, and an Inflammatory Index determined. It was found that all treatment modalities reduced inflammation significantly, when compared to the control. No differences among the three procedures tested were found. Although all permitted keratinization to develop, sulcular keratinization was significantly increased when daily prophylaxes were performed. It was concluded that mechanical stimulation of the sulcular epithelium, seemingly plays a role in promoting its keratinization.

Keratinization of the sulcular epithelium--a pointless pursuit?

A considerable amount of effort has been directed at finding methods for modifying the nonkeratinized sulcular epithelium on the assumption that a keratinized surface may offer a better barrier to antigens and bacterial products present in the gingival sulcus. It is argued here that keratinization in itself may not confer greater impermeability, for nonkeratinized epithelia also have been shown to resist the penetration of certain substances. Moreover, few workers have considered the role of junctional epithelium in the initiation of periodontal disease although experimental evidence suggests that this may be a permeable tissue. As formation of a surface with barrier properties seems to be a concomitant of epithelial differentiation while attachment is a property of relatively undifferentiated epithelial cells, attempts to induce junctional epithelium to differentiate could result in a loss of epithelial attachment to the tooth. It is suggested that attempts to keratinize the sulcular region, on theoretical grounds, may be unjustified.