Effect of Different Toothbrushing Routines on Interproximal Fluoride Concentration.

This study aimed to evaluate the effect of different toothbrushing routines and different kinds of toothpaste on the interproximal fluoride concentration after toothbrushing and its clinical relevance to the recommendations given to patients regarding the process of toothbrushing. Eight adults participated a total of 8 times in order to test different toothbrushing routines with different amounts of toothpaste (1 or 2 cm), durations (1 or 2 min) and amounts of water after toothbrushing (10 or 20 mL). An additional 8 adults participated 6 times in total to test different forms of toothpaste administration (paste, gel and foam) with different amounts of water after toothbrushing (no rinsing or 10 mL). Interdental saliva samples were collected from proximal sites 25/26 and 46/45 using small paper points, before and up to 60 min after toothbrushing. The fluoride concentration was measured by an ion-specific electrode. The area under the curve, saliva fluoride concentration versus time, was calculated. Differences between the groups were tested by ANOVA with Tukey's multiple comparisons test. An increase in fluoride concentration of 47.2% was observed when the amount of toothpaste increased from 1 to 2 cm (p < 0.01), 26.8% when increasing the duration from 1 to 2 min (p < 0.01) and 41.2% when reducing the amount of water rinsing from 20 to 10 mL (p < 0.01). The paste and gel resulted in higher fluoride concentration (p < 0.01) compared with foam. These findings suggest that the amount of toothpaste, the duration and the amount of water have a significant effect on fluoride concentration after toothbrushing. Furthermore, despite the lower amount of fluoride, the gel gives almost the same fluoride concentration after toothbrushing as the toothpaste. The results confirm the importance of giving clear advice to patients regarding the process of toothbrushing.

Relationship between oral symptoms during diving work and preventative dental visits in Japanese male occupational divers.

This cross-sectional study examined the relationship between dental symptoms experienced by occupational divers during diving and their participation in preventative dental visits. The questionnaire for this study was sent by post to 160 establishments and 215 members of the Japan Diving Association and participants were asked to complete a self-reported questionnaire. Data from 242 occupational divers (male, aged 20-79 yr) were analyzed. Multiple logistic regression analysis and correspondence analysis were performed to determine the relationship between dental symptoms experienced during diving and participation in preventative dental visits. We found that divers who experienced tooth pain while diving had not undergone preventative dental visits within the previous year (odds ratio: 2.76, 95% confidence interval: 1.12-6.80). This was also confirmed by correspondence analysis These findings suggested that not undergoing preventative dental visits was related to tooth pain during diving.

Expression Profiles of NOS Isoforms in Dental Pulp and Odontoblasts in nNOS Knockout Mice.

Active oxygen and free radicals are involved in metabolism in cells and tissues. Immunohistological studies of related enzymes are few, and the morphological dynamics of these enzymes in dental pulp and odontoblasts remain to be elucidated. Nitric oxide synthase (NOS) has 3 isoforms: nNOS, iNOS, and eNOS. The aim of this study was to investigate the profiles of NOS isoforms in the absence of nNOS in dental pulp and odontoblasts. Five-week-old male C57BL/6 and nNOS knockout (KO) mice were sacrificed and expression of nNOS, iNOS, and eNOS determined immunohistochemically. Expression of nNOS was positive, whereas that of iNOS was negative and eNOS weakly positive in the dental pulp and odontoblasts of the control mice. In nNOS KO mice, expression of iNOS was positive in dental pulp and strongly positive in odontoblasts, whereas that of eNOS was stronger in fibroblasts, endothelial cells in the vicinity of blood vessels in the dental pulp, and odontoblasts. Expression of nNOS was negative in the nNOS KO mice. This suggests that iNOS and eNOS compensate for nNOS deficiency in vascular endothelial cells and fibroblasts in the dental pulp and odontoblasts.

Factors Associated with Untreated Decayed Teeth in Male Sales Workers: An Internet Survey.

The purpose of this study was to identify factors associated with untreated decayed teeth (DT) in male sales workers. The participants were recruited by screening a pool of Japanese registrants in an online database for eligibility for inclusion in the study. Between 20 February 2015 and 11 March 2015, those deemed eligible were asked to complete a questionnaire on the status of their oral health. Responses from a total of 142 male sales workers aged between 30 and 49 years were analyzed. Of these, 40 reported DT and 102 no untreated decayed teeth (NDT). The percentage of participants with DT was higher than that with NDT among night shift workers (p<0.001). A higher percentage of participants with DT reported pain when eating or drinking something cold (p=0.041), pain in the teeth or gingiva (p<0.001), or frequent stomatitis (p=0.030). A higher percentage of participants with DT reported eating between meals (p=0.027) and a lower percentage visiting a dental clinic in the past 6 months (p=0.017) compared with among participants with NDT. Those with NDT were more likely to report an inability to visit a dental clinic when they wanted to (p=0.033), but those with DT were more likely to report that their reasons for not visiting a dental clinic were that multiple visits were required for treatment (p=0.012) or that they did not like the treatment (p=0.005). Working the night shift (Odds Ratio [OR], 3.492; 95% Confidence Interval [CI], 1.347-8.725) and visiting a dental clinic in the past 6 months (OR, 0.084; 95%CI, 0.010-0.733) were identified as independent variables correlated with leaving DT untreated. Requiring oral health education and dental checkups at least once every 6 months may have a positive effect on oral health among male sales workers, especially those doing night shifts.

Relationship between Blood HbA1c Level and Decayed Teeth in Patients with Type 2 Diabetes: A Cross-sectional Study.

The purpose of this cross-sectional study was to determine whether there is an association between hemoglobin A1c (HbA1c) level and the presence or absence of decayed teeth in patients with type 2 diabetes mellitus. The patients and data on their age and sex, the presence or absence of dental claims, medical history of diabetes mellitus, and workplace dental examinations were obtained from a Japanese healthcare database available for epidemiological studies. The HbA1c levels were obtained from results of the Specific Health Checkups and Specific Health Guidance tests conducted by the Japanese Ministry of Health, Labour and Welfare. Data on a total of 1,897 patients were analyzed. Patients with poorly controlled diabetes (HbA1c≥6.5, n=779) had more decayed teeth than those in whom it was well controlled (HbA1c<6.5, n=1,118). Multiple logistic regression analysis with the presence or absence of decayed teeth as a dependent variable revealed a significant association between an HbA1c level of ≥8.0 and decayed teeth (odds ratio: 1.69; 95% confidence interval, 1.24-2.29), even after adjusting for dental attendance. This suggests that a poorly controlled blood HbA1c level is a risk factor for dental caries. More thorough oral hygiene instruction and education on preventive treatment for dental caries in patients with poorly controlled diabetes are needed.

Factors Associated with Undergoing Regular Dental Check-ups in Healthy Elderly Individuals.

The purpose of this study was to determine the distribution of healthy elderly individuals undergoing regular dental check-ups and identify any environmental or associated oral factors. A cross-sectional questionnaire survey was used to interview 216 individuals attending 2 welfare facilities for the elderly, of whom 160 were included in the final analysis. Items comprised age, sex, number of residual teeth, frequency of teeth/denture cleaning, subjective chewing ability, denture use, oral status, regular dental check-ups, visitation of the same dentist, number of dental visits in the past year, General Oral Health Assessment Index (GOHAI) (Japanese version) score, living situation, and use of routine medication. Individuals undergoing regular dental check-ups were defined as those with a primary dentist whom they saw for dental check-ups at least once a year. The rate of individuals undergoing regular dental check-ups was 75.0% in men aged 60-74 years, 58.8% in women aged 60-74 years, 70.0% in men aged 75 years or over, and 45.3% in women aged 75 years or over. Logistic regression analysis revealed a higher number of residual teeth (odds ratio [OR]=2.664 in comparison with those with fewer than 20 teeth, p=0.0427); cleaning teeth/dentures 3 or more times per day (OR=2.546 in comparison with cleaning them twice per day or less, p=0.0157); and a higher GOHAI score (OR=2.742 in comparison with those with a GOHAI score of less than 58, p=0.0263) as factors significantly correlated with undergoing regular dental check-ups. In conclusion, the results revealed that individuals undergoing regular dental check-ups had 20 or more residual teeth, cleaned their teeth/denture 3 or more times per day, and had a higher GOHAI score. This indicates that the best predictive factor for undergoing regular dental check-ups in healthy elderly individuals is their GOHAI score.

Number of Non-vital Teeth as Indicator of Tooth Loss during 10-year Maintenance: A Retrospective Study.

The purpose of this study was to investigate whether number of non-vital teeth was an indicator of tooth loss during maintenance. Thirty-three general practitioners provided data on 321 patients undergoing maintenance over 10 years. The number of present teeth (PT), smoking status, level of bone loss, number of non-vital teeth, and reason for tooth loss during that period were investigated. Multiple logistic regression was performed to identify whether the number of non-vital teeth was associated with tooth loss. The average number of lost teeth was 1.07±1.82; that of PT at baseline was 24.4±3.9; and that of non-vital teeth at baseline was 5.4±4.5. Multiple logistic regression revealed a significant association between >8 non-vital teeth and tooth loss during maintenance (odds ratio [OR]: 2.40; 95% confidence interval [CI]: 1.18-4.87). It also demonstrated relationships between >8 non-vital teeth and root fracture or caries (OR: 3.90; 95%CI: 1.68-9.03 or OR: 2.85, 95%CI: 1.14-7.10, respectively). The number of non-vital teeth was associated with tooth loss during maintenance. The results suggest that patients with many non-vital teeth before commencement of maintenance are particularly at risk of tooth loss due to root fracture or caries. Therefore, the number of non-vital teeth offers a useful indicator of potential tooth loss.

Treatment of Severe Chronic Periodontitis with Surgical and Prosthetic Intervention: A 9-year Follow-up Case Report.

A 60-year-old woman presented with the chief complaint of mobility of tooth #16. Gingival swelling and calculus were observed. Clinical examination revealed that 49.4% of sites had a probing depth (PD) of ≥4 mm and 72% of sites bleeding on probing. Radiographic examination revealed vertical bone resorption in #35 and horizontal resorption in other regions. Periapical region radiolucency on #16 and 27 suggested a perio-endo lesion. The clinical diagnosis was severe chronic periodontitis. Initial periodontal therapy mainly comprised the following: oral hygiene instruction; quadrant scaling and root planing (SRP); extraction of #16, 27, and 31; and placement of provisional restorations. Open flap debridement was performed for teeth with a PD ≥4 mm. Bone defects exceeding the root apex were found in #17, 41, 42, and 45 intraoperatively. Teeth #41, 42, and 45 were extracted. After confirming the stability of the periodontal tissue, final prostheses were placed on #14-17, 13-22, 35-37, 33-43, 44-46, and 47. Following reevaluation, the patient was placed on supportive periodontal therapy (SPT). After 6 years, the patient experienced dull pain in and pus discharge from #17. Repeated SRP yielded no improvement, so the tooth was extracted and a removable partial denture placed on #16 and 17. Nine years have passed since the start of SPT and the level of plaque control has remained adequate and periodontal condition stable.

Working Environment Factors Associated with Regular Dental Attendance.

The aim of this study was to identify factors in the working environment associated with regular dental attendance. Thirty-three general practitioners provided data on 488 patients who underwent dental maintenance between 2003 and 2015. The age of the patients ranged from 40 to 65 years. Appointment adherence, employment format, overtime work, night work, and subjective evaluation of work were investigated. Multiple logistic regression analysis was performed to identify factors associated with regular dental attendance. Among all participants, 296 (60.7%) were female, 320 (65.6%) worked full-time, 193 (39.5%) worked overtime, and 34 (7.0%) worked nights. The results of the analysis revealed that only night work was a significant factor after adjusting for sex, age, and employment format (odds ratio, 0.220; 95% confidence interval, 0.088-0.550). The results of this study suggest that night work disturbs regular dental attendance.

Temporal Expression Patterns of Clock Genes and Aquaporin 5/Anoctamin 1 in Rat Submandibular Gland Cells.

Circadian rhythms are essential for health and regulate various physiological functions. These rhythms are regulated by a negative-feedback loop involving clock genes in the suprachiasmatic nucleus (SCN) and peripheral tissues. The rate of secretion of salivary substances, ions, and water follows a circadian rhythm, however, the relationship between the molecular mechanism of salivary secretion and peripheral circadian rhythm is not yet clear. Anoctamin 1 (ANO1, also known as TMEM16A) and Aquaporin 5 (AQP5) play an important role in the transport of ions and water in the submandibular glands (SGs). We examined the interaction between the rhythmic expression pattern of the clock genes, Ano1 and Aqp5, in rat whole SGs as well as isolated acinar and ductal cells. Circadian rhythmic expression for Bmal1, Per1, Per2, Clock, Cry1, Cry2, Rorα, and Rev-erbα mRNAs, also called the clock genes, was observed in rat SGs by semi-quantitative RT-PCR analysis. We also observed rhythmic patterns in Ano1 and Aqp5 mRNA expression. The expression of ANO1 protein also showed circadian rhythm, as confirmed by western blot analysis. We could not observe any time delay between the peak expression of ANO1 protein and its mRNA. Expression levels of the clock gene mRNAs in the ductal cells was higher than that in acinar cells, however, rhythmic oscillations were observed in both. Our results suggest that SGs have peripheral clocks, and rhythmic expressions of Ano1 and Aqp5 along with the clock genes, may play an important role in the circadian regulation of salivary secretion.

Relationship between amount of overtime work and untreated decayed teeth in male financial workers in Japan.

OBJECTIVE: Continuous or frequent overtime work has been shown to have harmful effects on human health. Meanwhile, one of the main reasons for tooth loss is caries. The aim of this study was to assess the relationship between overtime work and untreated decayed teeth in male financial workers. METHODS: The participants were recruited by applying screening procedures to a pool of Japanese registrants in an online database. Participants filled out a questionnaire about their oral health, behavior, and working conditions. Participants comprised a total of 951 financial male workers, aged 25-64 years. RESULTS: The likelihood of tooth decay increased with amount of overtime work (p=0.002). After adjusting for age, income, educational background, oral hygiene behavior, snacking behavior, regular dental visitation, bad interpersonal relationships at work, and smoking habit, a multiple logistic regression analysis found that participants with 45-80 h of overtime work (odds ratio [OR], 2.56; 95% confidence interval [CI], 1.23-5.33) or over 80 h of overtime work (OR, 3.01; 95% CI, 1.13-7.97) were more likely to have untreated tooth decay. The percentage of participants who gave "too busy with work" as the reason for leaving decayed teeth untreated increased with amount of overtime (p<0.001). CONCLUSION: These results indicate that overtime work is strongly related to untreated decayed teeth. In addition to oral health education and dental checkups, decreasing stress and decreasing the amount of overtime work may also have a positive effect on oral health in the workplace.

Relationship between job stress and subjective oral health symptoms in male financial workers in Japan.

OBJECTIVE: The aim was to assess subjective oral health symptoms and job stress, as measured by self-assessment of how demanding the job is, in male financial workers. METHODS: The participants were recruited by applying screening procedures to a pool of Japanese registrants in an online database. For the stress check, 7 items about how demanding the job is were selected from The Brief Job Stress Questionnaire (BJSQ). Participants comprised a total of 950 financial male workers, ages 25 to 64. RESULTS: Participants who answered "I can't complete my work in the required time" had more decayed teeth (p=0.010). Participants who felt that their job is highly demanding (answered affirmatively to 6 or all 7 items) were more likely to report "often get food stuck between teeth" (p=0.030), "there are some foods I can't eat" (p=0.005), "bad breath" (p=0.032), and "jaw makes clicking sound" (p=0.032). The independent variable of total stress score of 24-28 was found to be correlated to at least three oral health symptoms (OR: 3.25; 95%CI: 1.66-6.35). CONCLUSION: These results indicate that certain job stress factors are associated with certain oral health symptoms, and that oral health symptoms are likely predictors of job stress.

Relationship between Obstructive Sleep Apnea and Self-assessed Oral Health Status: An Internet Survey.

The purpose of this study based on a cross-sectional internet survey was to investigate the relationship between risk of obstructive sleep apnea (OSA) and self-assessed oral health status. The participants, who comprised individuals registered with an online research company, were required to complete a self-reported questionnaire. Those answering in the affirmative to both of the following two questions were placed in the OSA-risk group, while those answering in the negative were assigned to the control group: 'Have other people noticed pauses in your breathing while you are sleeping?' and 'Do you feel excessively sleepy during the daytime?'. A total of 493 were included in the OSA-risk group and 2,560 in the control group. Among the total 3,053 respondents, the highest prevalence for OSA risk in men was in the 50-59-year age range, although this tended to level off after age 60 years. No such trend was observed in women, however. Multiple logistic regression analysis was performed to identify the relationship between risk of OSA and self-assessed oral health status. Significant correlations were observed with the following parameters: difficulty in opening mouth (odds ratio [OR]: 2.66; 95% confidence interval [CI]: 1.647-4.311), dry mouth (OR: 2.11; CI: 1.544-2.876), bad breath (OR: 1.69; CI: 1.309-2.186), gingival bleeding (OR: 1.48; CI: 1.134-1.932), and gingival swelling (OR: 1.44; CI: 1.046-1.981). These results suggest a relationship between risk of OSA and self-assessed oral health status, indicating that treating OSA might improve oral health status. Further study is needed to demonstrate a causal relationship between OSA and self-assessed oral health status, however.

Comparison of the oral health problems and behavior of male daytime-only and night-shift office workers: An Internet survey.

OBJECTIVE: The aim of this study was to compare the oral health problems and behavior of full-time male daytime-only and night shift office workers. METHODS: The participants were recruited by applying screening procedures to a pool of Japanese registrants in an online database. During the period of 20 February 2015 to 11 March 2015, participants were asked to complete a questionnaire about their oral health. A total of 325 daytime-only workers and 351 workers who sometimes worked night shifts, ages 30 to 69, were analyzed in this study. RESULTS: Overall, the mean number of teeth of the night shift workers was lower than that of the daytime-only workers (p=0.002). When analyzed by age group, a significant difference was seen in the 50-69 age group (p=0.016). The percentage of night shift workers with decayed teeth was higher than that of the daytime-only workers (p<0.001). The night shift workers were more likely to report gingival bleeding (p=0.015) and stomatitis (p=0.025) than the daytime-only workers. The percentage of night shift workers reporting frequent brushing behavior was lower than that of the daytime-only workers (p=0.040). The independent variables found to correlate significantly with tooth decay were night shift work (OR, 1.79; 95% CI, 1.20-2.67), current smoking habit (OR, 1.66; 95% CI, 1.13-2.46), and BMI of ≥25 (OR, 1.56; 95% CI, 1.02-2.39). CONCLUSIONS: These results indicate a relationship between night shift work and oral health problems. Night shift workers may require additional support for oral health maintenance.

Comparison of risk factors for tooth loss between professional drivers and white-collar workers: an internet survey.

This cross-sectional study was conducted to examine tooth loss and associated factors among professional drivers and white-collar workers. The participants were recruited by applying screening procedures to a pool of Japanese registrants in an online database. The participants were asked to complete a self-reported questionnaire. A total of 592 professional drivers and 328 white-collar workers (male, aged 30 to 69 years) were analyzed. A multiple logistic regression analysis was performed to identify differences between professional drivers and white-collar workers. The results showed that professional drivers had fewer teeth than white-collar workers (odds ratio [OR], 1.74; 95% confidence interval [95% CI], 1.150-2.625). Moreover, a second multiple logistic regression analysis revealed that several factors were associated with the number of teeth among professional drivers: diabetes mellitus (OR, 2.68; 95% CI, 1.388-5.173), duration of brushing teeth (OR, 1.66; 95% CI, 1.066-2.572), frequency of eating breakfast (OR, 2.23; 95% CI, 1.416-3.513), frequency of eating out (OR, 1.70; 95% CI, 1.086-2.671) and smoking status (OR, 2.88; 95% CI, 1.388-5.964). These findings suggest that the lifestyles of professional drivers could be related to not only their general health status, but also tooth loss.

Metabolic Syndrome, Lifestyle, and Dental Caries in Japanese School Children.

The number of children with Metabolic Syndrome (MetS) has recently been increasing in Japan. Few studies have investigated the relationship between MetS and oral health. The aim of this study was to investigate the association between MetS, lifestyle, and oral health status in school children. Our goal is to utilize these results in health education aimed at preventing the onset of MetS in school children and adults. A total of 689 Japanese children (365 boys and 324 girls) aged between 10 and 13 years were examined and waist circumference (WC), ratio of WC to height, blood pressure, fasting blood sugar (FBS), high density lipoprotein-cholesterol, and triglyceride values determined together with oral health status, including dental caries experience (DMFT). The results revealed that 6.5% of the children fell under the health board recognized "MetS or high risk of MetS" (MetS/HR) classification. A total of 140 (20%) children had a high Streptococcus mutans count. The mean WC, FBS, and DMFT values were significantly greater in children with a high salivary S. mutans count (p<0.05). Multiple logistic regression analysis revealed a statistically significance association between MetS/HR, non-breakfast eaters (odds ratio (OR): 2.70), no regular exercise (OR: 2.60), and a high salivary S. mutans count (≥10(5) CFU/ml; OR: 2.18; p<0.05). The present results indicate that lifestyle and salivary S. mutans count could be useful in screening children for MetS/HR. These variables may be useful in targeting interventions aimed at preventing MetS in school children.

Comparison of Dental Explorers and CPI-probes in Diagnosing Dental Caries.

The primary aim of the present study was to compare efficiency in detecting suspected caries requiring observation (CO) and decayed teeth (DT) between dental explorers and Community Periodontal Index (CPI)-probes in school dental examinations and evaluate the effect of their respective use on Decayed, Missing, Filled Teeth (DMFT) Index scores. A total of 126 elementary and high school students were examined. All the clinical findings were obtained by a pair of trained dentists examining each student at routine annual school dental examinations. A dental explorer or CPI-probe and dental mirror were used for the examination. One dentist used the dental explorer, while the other used the CPI-probe. The choice of which instrument to use by the first dentist to examine the student was made at random. A comparison of the explorers and CPI-probes revealed that the numbers of patients and permanent teeth classified as CO were greater with the former in 6th-grade elementary and high school students (p<0.05). The Kappa value for CO and DT was 0.560 for 6th-grade elementary school and 0.846 for high school students. All DMFT scores were higher with the explorers than with the CPI-probes in the 6th-grade elementary school students. No significant difference was observed between the explorers and CPI-probes in any of the DMFT scores in any group, however. The present results indicate that as long as the low rate of caries in Japanese school children is maintained, the epidemiological data on this disease should not show any significant change if a CPI-probe is used instead of an explorer in school dental examinations.

Correlations between Perceived Oral Malodor Levels and Self-Reported Oral Complaints.

Objectives. Even though objective data indicating the absence of oral malodor are presented to patients, they may be skeptical about the results, possibly due to the presence of some discomfort in the oral cavity. The objective of this study was to investigate whether there is an association among self-perceptions of oral malodor, oral complaints, and the actual oral malodor test result. Materials and Methods. Questions concerning self-perceptions of oral malodor and subjective intraoral symptoms were extracted from a questionnaire on oral malodor completed by 363 subjects who visited the clinic for oral malodor of Tokyo Dental College Chiba Hospital and gave consent to this study. In addition, the association of self-perception of oral malodor with values obtained after organoleptic and OralChroma measurement was analyzed. Results. No correlation between 195 subjects (54%) who were judged "with oral malodor" (organoleptic score of ≥1) and 294 subjects (81.6%) who had a self-perceptions of oral malodor was observed. Self-perception of oral malodor was significantly correlated with tongue coating (p = 0.002) and a strange intraoral taste (p = 0.016). Conclusions. Subjects with a self-perception of oral malodor were not necessarily consistent with those actually having an oral malodor. In addition, it was suggested that patients became aware of oral malodor when they felt oral complaints.

Estimated tooth loss based on number of present teeth in Japanese adults using national surveys of dental disease.

Oral health instruction for adults should take into account the potential effect of tooth loss, as this has been suggested to predict further tooth loss. Therefore, the purpose of this study was to determine whether further tooth loss could be predicted from the number of present teeth (PT). We employed the same method as in our previous study, this time using two national surveys of dental disease, which were deemed to represent a generational cohort. Percentiles were estimated using the cumulative frequency distribution of PT from the two surveys. The first was a survey of 704 participants aged 50-59 years conducted in 2005, and the second was a survey of 747 participants aged 56-65 years conducted in 2011. The 1st to 100th percentiles of the number of PT were calculated for both age groups. Using these percentiles and a generational cohort analysis based on the two surveys, the number of teeth lost per year could be calculated. The distribution of number of teeth lost generated a convex curve. Peak tooth loss occurred at around 12-14 PT, with 0.54 teeth being lost per year. The percentage of teeth lost (per number of PT) increased as number of PT decreased. The results confirmed that tooth loss promotes further tooth loss. These data should be made available for use in adult oral health education.

Sex- and age-based differences in single tooth loss in adults.

The aim of this study was to investigate sex- and age-based differences in single tooth loss in adults. The data were obtained from the results of a periodontal disease examination carried out under a health promotion law in a city in Japan in 2005. Baseline data from a total of 3,872 participants aged 40 or 60 years comprising 1,302 men and 2,570 women were available. Only participants with 27 present teeth were eligible for inclusion in the analysis, giving a total of 218 men and 428 women. Third molars were excluded from the study. The bilateral total of each type of tooth was obtained. The mandibular first molar was missing in 26.7% of the men and 36.2% of the women among 40-year-olds and 35.3% of the men and 29.8% of the women among 60-year-olds. The mandibular second molar was missing in 14.7% of the men and 12.5% of the women among 40-year-olds, and 17.6% of the men and 18.4% of the women among 60-year-olds. Significant differences were observed between men and women in the mandibular second premolars and first molars among 40-year-olds. These results suggest that we need to pay more attention to individual teeth which are at particularly high risk for tooth loss, namely the mandibular first and second molars, and especially the mandibular first molars in middle-aged women.