An ex-vivo multiplexed antibacterial test on oral microflora

BACKGROUND/AIMS: Characterized clinical strains of oral bacteria are utilized to examine the antimicrobial efficacy of oral care formulations. A demonstration of antimicrobial effects of formulations on microbial samples obtained from the human mouth offers advantages, i.e. incorporates the considerable microbial diversity of this environment with bacteria harvested from naturally occurring biofilms to form the focus of this investigation. MATERIALS AND METHODS: Samples of oral flora from each adult subject were briefly treated (2 min) with test and control formulations and plated on appropriate agar for multiplexed antimicrobial effects on functional groups of oral bacteria associated with specific conditions. RESULTS: Ex-vivo treatments of oral samples with the triclosan/copolymer dentifrice demonstrated significant dose-dependent antimicrobial effects compared with a control formulation on anaerobic and facultative oral bacteria from a group of 16 volunteers (P < 0.05) with reproducible effects observed in three separate trials (P < 0.05). Similarly, significant dose-dependent effects were noted with chlorhexidine mouthrinses (P < 0.05). A simultaneous assessment of the effects of these formulations on several functional classes of oral bacteria associated with specific oral conditions such as dental caries and oral malodor demonstrated multiplexed antimicrobial activity (P < 0.05). CONCLUSIONS: A rapid procedure using small volumes of human oral samples and well-known formulations demonstrates ex-vivo multiplexed antimicrobial effects on functional groups of bacteria with both dentifrices and mouthrinses. Modifications of this approach may include antibacterial effects over time with formulations at clinically relevant concentrations, effects of novel agents or samples from subjects stratified on the basis of their clinical status.     

Comparing dose–response measurements of oral habits on oral leukoplakia and oral submucous fibrosis from a community screening program

J Oral Pathol Med (2010) 39 : 306–312 Background: Many studies have reported that the interaction and dose–response effects of betel quid chewing, tobacco smoking and alcohol drinking habits are important risk factors for oral cancer and precancerous lesions or conditions. These results are useful for comparing statistics, but may not be informative for personal disease‐related information. Methods: This study used data from a community screening program to evaluate the dose–response effects of daily frequency and duration from oral habits in Taiwan. The receiver operating characteristic (ROC) curves were further used to compare exposure measurements on indicating the occurrence of lesions/conditions. Results: Our results showed that the highest prevalence was found in leukoplakia (11.1%) and followed by oral submucous fibrosis (OSF, 4.4%). Betel quid chewing habit was found to have dose–response effects on leukoplakia and OSF, cigarette smoking habit only has the dose–response effect on leukoplakia, and alcohol drinking was not associated with both oral precancers. The daily frequency of chewing habit is a better indicator than other dose–response measurements for the occurrence of precancers. In addition, the cut‐off points of two to five counts per day have about 60–82% of sensitivities and 79–88% of specificities. Conclusions: The cut‐off points from ROC curves can provide an informative message to people with oral habits and their chances of developing diseases. High daily frequency of chewing can lead to excessive irritation to oral mucosa. Although the tobacco is never added to chewing quid in Taiwan, intensive irritation may play an important role in developing oral precancers in Taiwan.     

An ex‐vivo multiplexed antibacterial test on oral microflora

Background/aims: Characterized clinical strains of oral bacteria are utilized to examine the antimicrobial efficacy of oral care formulations. A demonstration of antimicrobial effects of formulations on microbial samples obtained from the human mouth offers advantages, i.e. incorporates the considerable microbial diversity of this environment with bacteria harvested from naturally occurring biofilms to form the focus of this investigation. Materials and methods: Samples of oral flora from each adult subject were briefly treated (2 min) with test and control formulations and plated on appropriate agar for multiplexed antimicrobial effects on functional groups of oral bacteria associated with specific conditions. Results: Ex‐vivo treatments of oral samples with the triclosan/copolymer dentifrice demonstrated significant dose‐dependent antimicrobial effects compared with a control formulation on anaerobic and facultative oral bacteria from a group of 16 volunteers (P < 0.05) with reproducible effects observed in three separate trials (P < 0.05). Similarly, significant dose‐dependent effects were noted with chlorhexidine mouthrinses (P < 0.05). A simultaneous assessment of the effects of these formulations on several functional classes of oral bacteria associated with specific oral conditions such as dental caries and oral malodor demonstrated multiplexed antimicrobial activity (P < 0.05). Conclusions: A rapid procedure using small volumes of human oral samples and well‐known formulations demonstrates ex‐vivo multiplexed antimicrobial effects on functional groups of bacteria with both dentifrices and mouthrinses. Modifications of this approach may include antibacterial effects over time with formulations at clinically relevant concentrations, effects of novel agents or samples from subjects stratified on the basis of their clinical status.     

Role of oral microbiome in oral oncogenesis,tumor progression,and metastasis

Squamous cell carcinoma is the most common malignant tumor of the oral cavity and its adjacent sites, which endangers the physical and mental health of patients and has a complex etiology. Chronic infection is considered to be a risk factor in cancer development. Evidence suggests that periodontal pathogens, such as Porphyromonas gingivalis, Fusobacterium nucleatum, and Treponema denticola, are associated with oral squamous cell carcinoma (OSCC). They can stimulate tumorigenesis by promoting epithelial cells proliferation while inhibiting apoptosis and regulating the inflammatory microenvironment. Candida albicans promotes OSCC progression and metastasis through multiple mechanisms. Moreover, oral human papillomavirus (HPV) can induce oropharyngeal squamous cell carcinoma (OPSCC). There is evidence that HPV16 can integrate with host cells’ DNA and activate oncogenes. Additionally, oral dysbiosis and synergistic effects in the oral microbial communities can promote cancer development. In this review, we will discuss the biological characteristics of oral microbiome associated with OSCC and OPSCC and then highlight the mechanisms by which oral microbiome is involved in oral oncogenesis, tumor progression, and metastasis. These findings may have positive implications for early diagnosis and treatment of oral cancer.     

西吡氯铵含漱液辅助治疗口腔念珠菌感染临床观察

目的通过临床试验评价西吡氯铵含漱液对口腔白色念珠菌感染的治疗作用. 方法选择在粘膜科就诊的白色念珠菌感染患者60例,分为试验组、复方氯已定对照组和制霉菌素甘油对照组,经治疗后观察其临床表现和涂片检查结果的变化,从而分析其疗效. 结果西吡氯铵含漱液对白色念珠菌感染患者的临床表现有改善作用,对白色念珠菌有一定的抑制作用,未发现明显的副作用. 结论西吡氯铵含漱液对白色念珠菌感染有一定的治疗作用,由于其口感较好且无口腔粘膜及牙齿着色,是临床治疗和预防口腔念珠菌感染的一种安全有效的辅助药物.     

Effects of the COVID-19 pandemic on children’s oral health and oral health care use

BackgroundThe COVID-19 pandemic led to early restrictions on access to oral health care and social distancing requirements. The authors examined the early effects of the COVID-19 pandemic on children’s oral health and access to oral health care in the United States.MethodsUsing nationally representative data from the National Survey of Children’s Health, the authors compared several measures of children’s oral health and oral health care use early during the pandemic in 2020 with 1 year earlier. Logistic (multinomial or binary) regression models were estimated, adjusting for several child and household covariates and state fixed effects. Similar comparisons were estimated for 2019 relative to 2018 to evaluate prepandemic trends.ResultsChildren in 2020 were 16% (relative risk ratio, 0.84; 95% CI, 0.75 to 0.93) less likely to have excellent dental health as perceived by parents and 75% (relative risk ratio, 1.75; 95% CI, 1.14 to 2.67) more likely to have poor dental health than in 2019. In addition, children in 2020 had higher risk of bleeding gingivae (odds ratio, 1.46; 95% CI, 1.16 to 1.85). The likelihood of having a dental visit in the past 12 months was 27% (odds ratio, 0.73; 95% CI, 0.65 to 0.82) lower in 2020, including lower likelihood for preventive visits. The differences between 2020 and 2019 were observed across demographic and socioeconomic subgroups. There were no such differences between 2019 and 2018.ConclusionsThere was a widespread decline in children’s oral health status and access to oral health care early during the COVID-19 pandemic.Practical ImplicationsPrompt policies and oral health campaigns are needed to counter the pandemic effects and increase timely access to dental services.     

口腔卫生健康指导对孕期妇女口腔健康的促进作用

目的:观察口腔卫生健康指导对孕期妇女口腔健康的促进作用。方法:从2010—2011年在海珠区妇幼保健院进行产前检查的初孕妇进行初筛后,从中选择780名,经基线检查并对相关口腔疾病治疗后,分为实验组(350名)和对照组(430名),实验组由口腔医师定期进行口腔卫生指导,对照组不进行口腔卫生指导。6个月后口腔检查,评价口腔卫生健康指导对孕期妇女口腔健康的作用。结果:经过口腔卫生健康指导后,实验组口腔卫生状况优于对照组(P<0.05),牙龈炎、龋病发病率均低于对照组(P<0.05)。结论:孕妇口腔卫生健康指导对其口腔健康具有促进作用,建议纳入社区卫生服务范围。     

Chemoprevention of oral cancer by green tea

Green tea has been a popular beverage for many centuries. Only recently, however, has the anti-cancer power of green tea constituents been unveiled. Green tea polyphenols are found to induce apoptosis (programmed cell death) in many types of tumor cells, including oral cancer cells. However, mechanisms that enable normal cells to evade the apoptotic effect still are not understood. In this study, cell growth and invasion assays combined with apoptosis assays were used to examine the effects of green tea extracts, green tea polyphenols, and the most potent green tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG), on normal human keratinocytes and oral carcinoma cells. The results showed that green tea and its constituents selectively induce apoptosis only in oral carcinoma cells, while EGCG was able to inhibit the growth and invasion of oral carcinoma cells. These differential responses to green tea and its constituents between normal and malignant cells were correlated with the induction of p57, a cell cycle regulator. These data suggest that the chemopreventive effects of green tea polyphenols may involve a p57 mediated survival pathway in normal epithelial cells, while oral carcinoma cells undergo an apoptotic pathway. Therefore, regular consumption of green tea could be beneficial in the prevention of oral cancer.     

Antimicrobial effects of a new therapeutic liquid dentifrice formulation on oral bacteria including odorigenic species.

The control of oral malodor is well-recognized in efforts to improve oral health. Antimicrobial formulations can mitigate oral malodor, however, procedures to assess effects on oral bacteria including those implicated in halitosis are unavailable. This investigation examined the antimicrobial effects of a new liquid triclosan/copolymer dentifrice (test) formulation that demonstrated significant inhibition of oral malodor in previous organoleptic clinical studies. Procedures compared antimicrobial effects of the test and control formulations on a range of oral micro-organisms including members implicated in halitosis, substantive antimicrobial effects of formulations with hydroxyapatite as a surrogate for human teeth and ex vivo effects on oral bacteria from human volunteers. With Actinomyces viscosus, as a model system, the test formulation demonstrated a dose-dependent effect. At these concentrations the test formulation provided significant antimicrobial effects on 13 strains of oral bacteria including those implicated in bad breath at selected posttreatment time points. Treatment of hydroxyapatite by the test dentifrice resulted in a significant and substantive antimicrobial effect vs. controls. Oral bacteria from subjects treated ex vivo with the test dentifrice resulted in significant reductions in cultivable oral bacteria and odorigenic bacteria producing hydrogen sulfide. In summary, microbiological methods adapted to study odorigenic bacteria demonstrate the significant antimicrobial effects of the test (triclosan/copolymer) dentifrice with laboratory and clinical strains of oral bacteria implicated in bad breath.     

Effects of S-PRG eluate on oral biofilm and oral malodor

ObjectivesThis study evaluated the effects of a surface pre-reacted glass-ionomer (S-PRG) eluate on oral microbiota and dental biofilms in vitro, and on oral malodor and tongue bacterial loads clinically.Study designThe effect of S-PRG eluate on the growth and survival of salivary bacteria was examined under both aerobic and anaerobic conditions; its ability to inhibit new biofilm formation and disrupt mature biofilms was also evaluated. The concentration of volatile sulfur compounds (VSCs) was measured using a portable sulfide monitor before and after rinsing with S-PRG eluate or distilled water. The number of bacteria on the tongue surface was calculated using a portable bacterial counter before and after tongue scraping with S-PRG eluate or distilled water.ResultsNo zone of inhibition was seen for S-PRG eluate against salivary microbiota under either aerobic or anaerobic conditions; however, treatment with ≥20% S-PRG eluate was sufficient to suppress biofilm formation relative to untreated controls. Mature biofilms were significantly disrupted following treatment with ≥60% S-PRG eluate relative to controls. Rinsing with S-PRG eluate significantly reduced the level of VSCs relative to baseline; this effect was not seen with distilled water alone. Waste fluids collected after oral rinsing with S-PRG eluate contained more bacteria than rinsing with distilled water alone. Finally, tongue scraping using S-PRG eluate was shown to significantly reduce the number of bacteria on the tongue surface.ConclusionsS-PRG eluate inhibits biofilm formation and disrupts mature biofilms, although its antibacterial activity is limited. Oral rinsing and tongue cleaning with S-PRG eluate may reduce oral malodor by effectively removing oral bacteria from the oral cavity.     

Bisphosphonates induce senescence in normal human oral keratinocytes

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) commonly occurs in individuals receiving bisphosphonates (BPs) with clinical manifestations of the exposed necrotic bone. Although defective wound healing of soft tissue is frequently, if not always, observed in BRONJ, the effects of BPs on oral soft tissue or cells remain unknown. To investigate the effects of BPs on cells of oral mucosal tissue, we studied the effect of pamidronate (PAM), one of the BPs most commonly administered to cancer patients, on the phenotypes of normal human oral keratinocytes (NHOK) and fibroblasts (NHOF). When exposed to PAM at 10 μM, NHOK, not NHOF, underwent senescence: NHOK overexpressed senescence-associated β-galactosidase (SA-β-Gal), p16INK4A, IL-6, and IL-8. When exposed to a higher level (50 μM) of PAM, NHOK maintained senescent phenotypes, but NHOF underwent apoptosis. PAM-induced senescence in NHOK is mediated, in part, via geranylgeranylation of the mevalonate pathway. Our in vitro 3D oral mucosal tissue construction studies further demonstrated that PAM induced senescence and impaired re-epithelialization of oral mucosa. Analysis of these data indicates that premature senescence of oral mucosal cells and subsequent defective soft-tissue wound healing might be partly responsible for the development of BRONJ in individuals receiving PAM or other BPs.     

Induction and inhibition of oral malodor

Volatile sulfur compounds (VSCs) such as hydrogen sulfide (H₂S) and methyl mercaptan (CH₃SH) are the main components of oral malodor, and are produced as the end products of the proteolytic processes of oral microorganisms. The main pathway of proteolysis is the metabolism of sulfur‐containing amino acids by gram‐negative anaerobic bacteria. Gram‐positive bacteria may promote VSC production by gram‐negative anaerobes by cleaving sugar chains from glycoproteins and thus providing proteins. A large variety of bacteria within the oral microbiota are thought to be involved in the complex phenomenon of halitosis. Oral microbiota associated with a lack of oral malodor, oral microbiota associated with severe and H₂S‐dominant oral malodor, and oral microbiota associated with severe and CH₃SH‐dominant oral malodor have been distinguished through molecular approaches using the 16S rRNA gene. Pathological halitosis may primarily be addressed through treatment of causative diseases. In all cases, plaque control is the basis of oral malodor control, and dentifrices, mouthwashes, and functional foods play a supplementary role in addition to brushing. Recently, the use of natural ingredients in products tends to be favored due to the increase in antibiotic‐resistant strains and the side effects of some chemical ingredients. In addition, probiotics and vaccines are expected to offer new strategies for improving the oral conditions through mechanisms other than antibacterial agents.     

短期口服氟康唑胶囊治疗糜烂型口腔扁平苔藓的疗效观察

目的:探讨糜烂型口腔扁平苔藓(oral lichen planus,OLP)患者口腔真菌感染的患病情况,观察短期口服氟康唑胶囊治疗糜烂型OLP的临床疗效。方法:纳入糜烂型OLP患者60例,健康志愿者30例,通过口腔真菌涂片检查,比较两组真菌感染患病率。将60例糜烂型OLP患者随机分为实验组和对照组,分别接受口服氟康唑胶囊和局部涂擦制霉菌素甘油治疗(治疗周期为7 d),比较两组治疗效果。结果:糜烂型OLP患者中真菌涂片阳性率显著高于健康志愿者。糜烂型OLP患者中口服氟康唑胶囊治疗有效率显著高于局部涂擦制霉菌素甘油,且在缓解症状指数方面,实验组效果较对照组明显。结论:糜烂型OLP患者是口腔真菌感染的高发人群。相较于局部涂抹制霉菌素甘油,口服氟康唑胶囊对于真菌感染和黏膜损害的疗效更好,且能更快缓解疼痛症状,推荐在糜烂型OLP患者的前期治疗阶段使用。     

Effects of personal oral hygiene and subgingival scaling on bleeding interdental gingiva

The aim of this study was to determine the effects of personal oral hygiene and subgingival scaling on bleeding interdental gingiva. The Eastman Interdental Bleeding Index (EIBI) was used to clinically evaluate interdental gingival status. Forty-seven bleeding interdental sites in 47 patients were divided into three groups. Sites in Group I bled on stimulation with wooden interdental cleaners. Groups II and III initially bled but were converted to nonbleeding with oral hygiene alone or oral hygiene combined with subgingival scaling, respectively. Interdental gingival biopsies were obtained and subjected to morphometric analysis to compare the three groups. The findings from this study indicated that: (A) personal oral hygiene reduced the magnitude and extent of the interdental inflammatory lesion; (B) subgingival scaling plus oral hygiene decreased the interdental inflammatory lesion to a greater extent than oral hygiene alone; (C) significant repair of the interdental lesion occurred within four weeks; and (D) the EIBI was an effective method for monitoring the effects of therapy directed towards resolution of the interdental inflammatory lesion.     

Effects of an oral health education program targeting oral malodor prevention in Japanese senior high school students

Abstract

Objective. Previous research has suggested that oral malodor could be a useful motivational tool for increasing the awareness of oral health in adolescents and improving their oral health behaviors. Hence, the aims of this research were: (1) to develop an oral health education program that included oral malodor prevention and (2) to test the effects of the program in Japanese senior high school students by comparing the changes of oral health outcomes between the intervention and control groups. Materials and methods. Subjects were 163 Grade 1 and 135 Grade 2 senior high school students in Tokyo, Japan. A novel oral health education program, which incorporated prevention of oral malodor, was developed and conducted on all Grade 1 students (intervention group). Grade 2 students (control group) did not receive the program. Changes in oral health status from baseline to 1-year follow-up were compared between the intervention and control groups. Results. The intervention group, compared with the control group, had a significantly higher proportion of students who improved or maintained good oral health status (i.e. dental plaque, gingivitis, tongue coating and oral malodor). Among students in the intervention group, the change was more evident in subjects with detectable oral malodor at the commencement of the program. Conclusions. An oral health education program focusing on the prevention of oral malodor is effective for promoting oral health among Japanese senior high school students. Therefore, embedding such a program in the school oral health curriculum would be beneficial for adolescents.     

The effect of daily controlled oral hygiene on the oral health of children in a town with drinking water fluoridation (Karl Marx Stadt)]

Under the conditions of an optimized (with regard to caries prevention) fluoride content of the drinking uater, the authors studied (in the framework of an oral hygiene measure covering 32 months) in 149 children 6.5-8 years of age the effects of supervised daily dental and oral care on dental health. The improvement in oral hygiene (OHI) by 33% is in harmony with an additional caries reduction by 33.3% (DMF/S index) and a decrease of the PM index by 47%. A wider use of oral hygiene actions as secondary preventive measures is, therefore, recommended also for towns with fluoridated drinking water.     

Copper stimulates human oral fibroblasts in vitro: a role in the pathogenesis of oral submucous fibrosis

Copper is implicated in the pathogenesis of several fibrotic disorders. Areca nut has been shown to have a high copper content and areca chewing is associated with oral submucous fibrosis (OSF). The effects of copper on human oral fibroblasts were investigated in vitro. Human oral fibroblasts were incubated with copper chloride (CuCl2) at concentrations ranging from 0.01 microM to 500 microM for 24 h, and in vitro cell proliferation was assayed by incorporation of tritiated-thymidine; soluble and non-soluble collagen synthesis was assayed using tritiated-proline. Addition of copper chloride at concentrations ranging from 0.1 microM to 50 microM increased the collagen synthesis by the oral fibroblasts compared with growth without copper (P<0.05). The addition of copper chloride neither increased the synthesis of non-collagenous proteins by the fibroblasts nor influenced their proliferation rate. We conclude that copper upregulates collagen production in oral fibroblasts. This appears to be concentration dependent, with peak collagen synthesis at 50 microM CuCl2. These in vitro results taken together with the recent findings of copper in oral biopsies from OSF subjects support the hypothesis that copper in areca nut acts as a mediator of OSF.     

Influence of borneol on primary mice oral fibroblasts: a penetration enhancer may be used in oral submucous fibrosis

Background:  Borneol, a widely used food and cosmetics additive, has analgesic, anti-inflammatory, antibacterial and penetration enhancing effects. We try to use it as a penetration enhancer for a formula which we have used to treat oral submucous fibrosis (OSF). To assess its safety, we investigate its effects on primary mice oral fibroblasts.
Methods:  Primary mice oral fibroblasts were cultured, the effects of borneol on fibroblasts proliferation, cytotoxicity, collagen production, matrix metalloproteinases-2,9 (MMP-2,9) activities and tissue inhibitors of metalloproteinase 1 (TIMP-1) production were tested by methyl thiazolyl tetrazolium assay, lactic dehydrogenase activity assay, chloramine T method, gelatin zymography and enzyme-linked immunosorbent assay, respectively.
Results:  Borneol, from 18.75 to 300 μg/ml, could significantly ( P  < 0.05) decrease the growth of fibroblasts and very significantly ( P  < 0.01) inhibit collagen production in a concentration dependant manner. From 18.75 to 150 μg/ml, borneol had no cytotoxicity on mice oral fibroblasts. Moreover borneol could significantly ( P  < 0.05) decrease MMP-2 activity, and very significantly ( P  < 0.01) inhibit TIMP-1 production.
Conclusions:  This study indicates that borneol has anti-fibrosis activity and the mechanism may partly be relevant to its inhibiting effects on fibroblasts mitosis, collagen and TIMP-1 production. It can be safely used as a penetration enhancer for our formula to treat OSF.     

Comparison of oral ketamine and oral midazolam as sedative agents in pediatric dentistry

The safe and effective treatment of uncooperative or combative preschool children with extensive dental needs is one of pediatric dentist's ongoing challenges. The traditional methods of behavior management are no longer acceptable to parents as they are not ready to spare more time for dental treatment of their children. Keeping this in mind, the present study was designed and carried out to evaluate the sedative effects of oral ketamine and oral midazolam prior to general anesthesia. Twenty uncooperative children in the age-group of 2-6 years were selected after thorough medical examination and investigations. Informed consent was obtained from the parent. This was a randomized double-blind study. An anesthesiologist administered either 0.5 mg/kg midazolam or 5 mg/kg ketamine orally. The heart rate, respiratory rate, and oxygen saturation were recorded at regular intervals. The sedation and anxiolysis scores were also recorded. The parents were asked to answer a questionnaire at the follow-up session the next day on the surgical experience of the parent and the child and side effects experienced, if any. When the data was subjected to statistical analysis, it was observed that both drugs resulted in adequate sedation at the end of 30 min, with oral midazolam providing significantly better anxiolysis. The heart rate and respiratory rate were marginally higher with oral ketamine. The questionnaire revealed a better response with oral midazolam; side effects were more prominent with oral ketamine.     

Treatment of oral submucous fibrosis by collagenase: effects on oral opening and eating function

OBJECTIVE: Patients with oral submucous fibrosis (OSF) suffer from the limitation of the oral opening. The aim of this study was to develop a simple and rapid method to improve the opening of the oral cavity and determine its effect on the incidence of developing oral carcinoma. METHODS: We first induced an OSF-like lesion in rabbits which histopathologically resembles OSF in betel nut chewers and evaluated the effects of exogenous collagenase on these lesions. We then applied the collagenase treatment regimen to patients with OSF. RESULTS: Endogenous collagenase activities in normal oral mucosa of patients exhibited 3- to 5-fold higher levels than that of OSF tissues. The collagenase treatment not only resulted in a significant improvement of oral opening, but patients also experienced a striking reduction in hypersensitivity to spices, sour, cold, and heat which helped restore eating function. Sub-mucosal fibrous proliferation, persistently good vascularization, and a mild increase in thickness of the sub-mucosal fibrous tissues were noticed 10 months after collagenase treatment. Within the 2-year follow-up period none of the treated patients developed an oral squamous cell carcinoma. CONCLUSION: A reduced content of functional collagenase observed in OSF mucosa of patients might be one mechanism responsible for collagen accumulation. Intervention of OSF by collagenase treatment at the early stage may reduce the incidence of developing oral carcinoma.