Pigmentazioni dentarie da clorexidina: una revisione critica

OBJECTIVES To propose a critical review on chlorhexidine-induced oral discoloration, including the mechanisms, the prevalence and the factors influencing onset and severity. Additionally, this paper investigates the clinical efficacy of the Anti-Discoloration System based on sodium metabisulfite and ascorbic acid (ADS). MATERIALS AND METHODS A literature search was conducted using in combination the following keywords: Chlorhexidine, Mouthwash, Staining, Anti- Discoloration System, Gingivitis, Plaque. Scientific papers and literature reviews in English, German and Italian were included. The literature evaluation on the efficacy of ADS was performed including 12 randomized controlled clinical trials designed to assess the anti-plaque, anti-gingivitis and anti-discoloration effects of mouthwashes containing chlorhexidine and ADS. These mouthwash products were commercially available in Italy. Clinical studies that tested Anti- Discoloration Systems different from ADS were not considered. RESULTS The possible mechanisms involved in the development of oral discolorations (non-enzymatic browning reaction, also known as the Maillard reaction, formation of iron and tin sulfides, precipitation of food chromogens, individual susceptibility) and the prevalence of pigmentations were presented. The factors that influence the onset and severity of pigmentations include chlorhexidine concentration, plaque on tooth surfaces, dietary consumption of food and beverages containing chromo¬gens, and tobacco smoking. The ADS is an Anti-Discoloration System patented since 2003 and added to mouthwashes available on the Italian market. The ADS reduces tooth discolorations by inhibiting non-enzymatic browning reaction and formation of chromogenic metal sulphides. Most studies showed that the mouthwash containing ADS is ef¬fective in reducing tooth discolorations while maintaining the ch-lorhexidine efficacy with respect to reduction of plaque and gingivitis. These results were confirmed by a meta-analysis including clinical trials testing both ADS and systems alternative to ADS (qua-lity of the evidence: weak to moderate). CONCLUSIONS In the 12 studies included considerable methodological heterogeneity was observed and this could be responsible for the discrepancy in results, particularly with respect to anti-plaque activity. Further clinical trials, homogenous in design, are needed. The inclusion of periodontitis patients and/or undergoing periodontal surgery, diet restrictions, timing of recording plaque and gingivitis indices, and suspension of oral hygiene are potentially important with respect to design homogeneity. CLINICAL SIGNIFICANCE A recent meta-analysis confir¬med that the addiction of an Anti-Discoloration System to chlorhexidine mouthwash reduces tooth discoloration in situations in which toothbrushing is not involved (quality of the evidence: moderate). Meta-analysis also indicated that the addiction of an Anti-Discoloration System does not affect the anti-plaque and anti-gingivitis efficacy of chlorhexidine (quality of the evidence: weak to moderate).