Collaborative meta-analysis finds no evidence of a strong interaction between stress and 5-HTTLPR genotype contributing to the development of depression.

The hypothesis that the S allele of the 5-HTTLPR serotonin transporter promoter region is associated with increased risk of depression, but only in individuals exposed to stressful situations, has generated much interest, research and controversy since first proposed in 2003. Multiple meta-analyses combining results from heterogeneous analyses have not settled the issue. To determine the magnitude of the interaction and the conditions under which it might be observed, we performed new analyses on 31 data sets containing 38 802 European ancestry subjects genotyped for 5-HTTLPR and assessed for depression and childhood maltreatment or other stressful life events, and meta-analysed the results. Analyses targeted two stressors (narrow, broad) and two depression outcomes (current, lifetime). All groups that published on this topic prior to the initiation of our study and met the assessment and sample size criteria were invited to participate. Additional groups, identified by consortium members or self-identified in response to our protocol (published prior to the start of analysis) with qualifying unpublished data, were also invited to participate. A uniform data analysis script implementing the protocol was executed by each of the consortium members. Our findings do not support the interaction hypothesis. We found no subgroups or variable definitions for which an interaction between stress and 5-HTTLPR genotype was statistically significant. In contrast, our findings for the main effects of life stressors (strong risk factor) and 5-HTTLPR genotype (no impact on risk) are strikingly consistent across our contributing studies, the original study reporting the interaction and subsequent meta-analyses. Our conclusion is that if an interaction exists in which the S allele of 5-HTTLPR increases risk of depression only in stressed individuals, then it is not broadly generalisable, but must be of modest effect size and only observable in limited situations.

Evolution of public attitudes about mental illness: a systematic review and meta-analysis.

OBJECTIVE: To explore whether the increase in knowledge about the biological correlates of mental disorders over the last decades has translated into improved public understanding of mental illness, increased readiness to seek mental health care and more tolerant attitudes towards mentally ill persons. METHOD: A systematic review of all studies on mental illness-related beliefs and attitudes in the general population published before 31 March 2011, examining the time trends of attitudes with a follow-up interval of at least 2 years and using national representative population samples. A subsample of methodologically homogeneous studies was further included in a meta-regression analysis of time trends. RESULTS: Thirty-three reports on 16 studies on national time trends met our inclusion criteria, six of which were eligible for a meta-regression analysis. Two major trends emerged: there was a coherent trend to greater mental health literacy, in particular towards a biological model of mental illness, and greater acceptance of professional help for mental health problems. In contrast, however, no changes or even changes to the worse were observed regarding the attitudes towards people with mental illness. CONCLUSION: Increasing public understanding of the biological correlates of mental illness seems not to result in better social acceptance of persons with mental illness.

Impact of operators' experience and patients' age on the success of nitrous oxide sedation for dental treatment in children.

AIM: To evaluate the success rates and potential influencing factors of nitrous oxide sedation for dental treatment in a specialised paediatric dental service. MATERIALS: Medical records of all children treated under nitrous oxide sedation in a specialised pedodontics clinic between 2012 and 2017 were analysed retrospectively for parameters such as age of the patient, experience and change of operating dentists, treatment procedure and success or failure regarding the sedation and treatment. CONCLUSION: Given the high overall success rate of over 90%, nitrous oxide sedation can be a highly effective treatment option for performing dental treatment in pre-cooperative and/or anxious children and adolescents. With age of the children and experience of the dentist, success rates increased.

The growth hormone--IGF-I axis as a mediator for the association between FTO variants and body mass index: results of the Study of Health in Pomerania.

CONTEXT: Risk alleles of the fat mass- and obesity-associated gene (FTO) are related not only to increased body mass index (BMI) values but also to mortality. It was speculated that cellular effects of the FTO gene affect most organs, especially their ability to maintain or regenerate proper function when afflicted by various diseases. FTO is highly expressed in the hypothalamus and also in the pituitary gland. The decrease in growth hormone (GH) secretion is known to cause a decrease in lean body mass in older subjects. OBJECTIVE: We hypothesized an association of rs9926289 with insulin-like growth factor (IGF)-I. DESIGN AND SETTING: Cross-sectional data from the Study of Health in Pomerania, a population-based study in the northeastern part of Germany, were used. PARTICIPANTS: For the final analyses, 3882 subjects aged 20-79 years were available. MAIN OUTCOME MEASURES: Continuous IGF-I, low IGF-I according to clinically meaningful age- and gender-specific reference values, and BMI were used as outcome measures. RESULTS: Over all age groups, a statistically significant relationship between FTO and IGF-I was found. In subjects younger than 55 years of age, homozygous carriers of the FTO risk allele exhibited lower serum IGF-I levels adjusted for 5-year age groups, gender and IGF-I binding protein 3 levels (linear regression, coefficient±s.e. for FTO AA genotype:-8.6±2.8; P=0.002). Further adjustments for obesity and diabetes did not suspend this association (coefficient:-7.8; P=0.005). As expected, the FTO AA genotype effect on BMI was reduced from 0.76 to 0.62 kg m(-2) by including IGF-I. No relationship between FTO and IGF-I levels was found in subjects aged 55 years or older (-2.7±2.4; P=0.260 for FTO AA genotype adjusted for age, gender and IGF-I binding protein 3 levels). CONCLUSION: We propose that the GH-IGF-I axis is a mediator for the relationship between FTO and BMI.

Signs and symptoms of temporomandibular disorders and the incidence of tinnitus.

In a cross-sectional analysis of data from the Study of Health in Pomerania (SHIP 0), temporomandibular disorders (TMD) were the strongest predictors for tinnitus beside headache. The aim of this study was to investigate whether signs and symptoms of TMD can be identified as risk factors for developing tinnitus. The SHIP 1 is a population-based 5-year longitudinal study intended to systematically describe the prevalence of and risk factors for diseases common in the population of Pomerania in northern Germany. A total of 3300 subjects (76% response) were reevaluated after 5 years for tinnitus and signs and symptoms of TMD using the same questionnaires and examination tools as baseline. To estimate the relative risk (RR) appropriately, a modified Poisson regression was used. After exclusion of prevalent cases with diagnosed tinnitus, 3134 subjects were analysed. Among the 191 exposed subjects with palpation pain in the temporomandibular joint (TMJ), 24 subjects (12·6%) received diagnosed tinnitus after 5 years, whereas among the 2643 unexposed subjects 142 subjects (5·8%) received tinnitus yielding a risk difference of 7·7% (95% confidence interval [CI]: 3·0%-12·5%) and a risk ratio of 2·60 (95% CI: 1·7-3·9). The risk ratio was 2·4 (95% CI: 1·6-3·7) after adjustment for gender, age, school education and frequent headache. Pain on palpation of the TMJ, however, did not worsen the prognosis for tinnitus in prevalent tinnitus cases (RR = 0·8, P = 0·288). Signs of TMD are a risk factor for the development of tinnitus.

Self-reported chewing side preference and its associations with occlusal, temporomandibular and prosthodontic factors: results from the population-based Study of Health in Pomerania (SHIP-0).

This study investigated the prevalence of a preferred chewing side (PCS) and associations between a PCS and signs of temporomandibular disorders (TMD), antagonist contact and prosthetic restoration. A population representative sample of 4086 adults of the cross-sectional epidemiologic 'Study of Health in Pomerania' (SHIP-0) (age range 20-80 years, female 50.2%) was divided in two groups by the presence or absence of a PCS. PCS was evaluated by a questionnaire. Chi-squared tests and multiple logistic regression were used to determine the impact of the relation between a PCS and signs and symptoms of TMD as well as dental factors. The prevalence of a PCS was 45.4%. Women between 40 and 69 years reported more frequently a PCS. There was a preference for the right side (64%). The following independent variables were significantly associated with a PCS: subjective unilateral pain in the temporomandibular joint (TMJ), odds ratio (OR) 2.4; subjective unilateral joint clicking, OR 1.7; unilateral TMJ/muscle pain on palpation, OR 1.6/OR 1.3; loss of one supporting zone (Eichner-Classification), OR 1.9; loss of both supporting zones on one side, OR 2.2, one supporting zone left, OR 1.4; presence of a removable partial denture, OR 1.6; presence of an attachment restoration, OR 1.5. A PCS was found in almost half the study population and was associated with unilateral signs of TMD, most of all TMJ pain and asymmetrical loss of antagonist contact. Despite replacement of lost teeth not all restorations seemed to support bilateral mastication.

Influence of Age and Tooth Loss on Masticatory Muscles Characteristics: A Population Based MR Imaging Study.

BACKGROUND: Aging is associated with a decline in masticatory muscles mass and performance. The present study aims to examine the differences in the cross-sectional areas of the masseter, medial and lateral pterygoid muscles in relation to age and the present dental status in a population-based magnetic resonance imaging study. METHODS: This cross sectional study involved 747 subjects aged between 30-89 years (344 male, 403 female) who underwent both a whole body MRI and a full oral examination. The cross-sectional areas of the masseter, medial and lateral pterygoid muscles were measured from MRI images using the software Osirix. Dental and prosthetic status data from the oral examination were classified according to Eichner index. The method of generalized least squares, also called growth curve model, was used to examine the associations between the cross-sectional areas, age and tooth status. RESULTS: The cross-sectional area of the lateral pterygoid muscle decreased substantially with age in women but did not depend on age in men. The medial pterygoid muscle depended on age but an effect modification by gender was uncertain. Masseter muscle was weakly associated with age but strongly associated with the number of teeth in both genders. CONCLUSIONS: Our findings suggest that age has a heterogeneous effect on masticatory muscles. This indicates that age related changes to the masticatory muscles are muscle specific and are not consistent between the different muscles.

Comparative clinical investigation of horizontal condylar inclination using the JMA electronic recording system and a protrusive wax record for setting articulators.

PURPOSE: The rationale for recording protrusive mandibular movement is to accurately adjust an articulator. Techniques to record condylar inclination include extraoral tracings and intraoral recording materials. This study compared horizontal condylar inclination angles (HCI) recorded with a protrusive interocclusal record and an electronic pantographic device, the Jaw Motion Analyzer (JMA). MATERIALS AND METHODS: Twenty-three volunteers (12 females; 11 males; mean age 46.7 years) were selected for this study. First, a protrusive interocclusal wax record after 5 mm protrusive movement was taken from the volunteers and the HCI angles were determined after mounting the volunteers' casts in 2 different articulators (SAM 2; Reference SL). Second, kinematic hinge axis and the HCIs were recorded after 5 mm protrusive movement from protrusive jaw tracks recorded with the JMA. ICC and mean values for HCI were used for statistical analysis. Mean differences of HCI between the measuring methods were compared by Bland Altman Plots. RESULTS: The agreement of the HCI between the articulators determined by the protrusive record was good. The mean HCI value recorded with the JMA was significantly higher compared to the values of the protrusive wax records. There was no agreement found between the different methods for calculating the HCI. CONCLUSION: A large variance in articulator settings obtained by interocclusal records is often found. The JMA was found reliable and valid for measuring HCI values. Within the limitations of this study, the use of a pantographic device should be considered for individually adjusting articulators rather than the use of protrusive records.

GWAS Identifies New Loci for Painful Temporomandibular Disorder: Hispanic Community Health Study/Study of Latinos.

Temporomandibular disorder (TMD) is a musculoskeletal condition characterized by pain and reduced function in the temporomandibular joint and/or associated masticatory musculature. Prevalence in the United States is 5% and twice as high among women as men. We conducted a discovery genome-wide association study (GWAS) of TMD in 10,153 participants (769 cases, 9,384 controls) of the US Hispanic Community Health Study/Study of Latinos (HCHS/SOL). The most promising single-nucleotide polymorphisms (SNPs) were tested in meta-analysis of 4 independent cohorts. One replication cohort was from the United States, and the others were from Germany, Finland, and Brazil, totaling 1,911 TMD cases and 6,903 controls. A locus near the sarcoglycan alpha ( SGCA), rs4794106, was suggestive in the discovery analysis ( P = 2.6 × 106) and replicated (i.e., 1-tailed P = 0.016) in the Brazilian cohort. In the discovery cohort, sex-stratified analysis identified 2 additional genome-wide significant loci in females. One lying upstream of the relaxin/insulin-like family peptide receptor 2 ( RXP2) (chromosome 13, rs60249166, odds ratio [OR] = 0.65, P = 3.6 × 10-8) was replicated among females in the meta-analysis (1-tailed P = 0.052). The other (chromosome 17, rs1531554, OR = 0.68, P = 2.9 × 10-8) was replicated among females (1-tailed P = 0.002), as well as replicated in meta-analysis of both sexes (1-tailed P = 0.021). A novel locus at genome-wide level of significance (rs73460075, OR = 0.56, P = 3.8 × 10-8) in the intron of the dystrophin gene DMD (X chromosome), and a suggestive locus on chromosome 7 (rs73271865, P = 2.9 × 10-7) upstream of the Sp4 Transcription Factor ( SP4) gene were identified in the discovery cohort, but neither of these was replicated. The SGCA gene encodes SGCA, which is involved in the cellular structure of muscle fibers and, along with DMD, forms part of the dystrophin-glycoprotein complex. Functional annotation suggested that several of these variants reside in loci that regulate processes relevant to TMD pathobiologic processes.

Magnesium deficiency is associated with periodontal disease.

In the multifactorial pathogenesis of periodontitis, there are still unknown factors influencing the outcome of the disease. An association between magnesium and periodontitis has been suggested by preliminary studies. However, relevant clinical data are lacking. We investigated the association between magnesium status and periodontal health in a population-based analysis. We conducted a cross-sectional epidemiological investigation involving 4290 subjects aged 20-80 yrs. We recorded periodontal risk factors and determined concentrations of serum magnesium and calcium, relating them to periodontal parameters. In a matched-pair study, 60 subjects using oral magnesium-containing drugs and 120 without were compared. In subjects aged 40 yrs and older, increased serum Mg/Ca was significantly associated with reduced probing depth (p<0.001), less attachment loss (p=0.006), and a higher number of remaining teeth (p=0.005). Subjects taking Mg drugs showed less attachment loss (p<0.01) and more remaining teeth than did their matched counterparts. These results suggest that nutritional magnesium supplementation may improve periodontal health.

Risk factors for goiter in a previously iodine-deficient region.

OBJECTIVE: Little information exists from formerly iodine-deficient areas regarding gender-specific risk factors for goiter and their synergisms. The aim of the present study was to investigate such gender-specific risk factors and their interactions in a large population-based sample. METHODS AND RESULTS: The Study of Health in Pomerania (SHIP) comprised 4310 randomly selected participants, aged 20 - 79 years. SHIP was performed in a previously iodine-deficient region. Data from 3915 participants with no known thyroid disorders were analyzed. Goiter was determined by thyroid ultrasound. Sociodemographic characteristics, smoking and alcohol drinking habits, marital status, education level, urine thiocyanate concentrations, and specifically in women, parity and previous or current use of oral contraceptives and hormone replacement therapy, were considered as candidate risk factors for multivariable statistical tests. Only two variables, an advanced age and current smoking, were independently associated with an increased risk for goiter in both genders. Analyses further revealed specific risk factor profiles for goiter which were different among men, pre- and postmenopausal women. CONCLUSION: We conclude that besides previous iodine deficiency, other risk factors for goiter exist which differ between gender. Among the avoidable risk factors, current smoking was strongly associated with the risk of goiter in men and women. These findings should influence activities which are intended to prevent thyroid disease.

The interleukin-1 polymorphism, smoking, and the risk of periodontal disease in the population-based SHIP study.

Several studies have shown a role for interleukin-1 gene cluster polymorphisms in the risk assessment for periodontal diseases. In the Study of Health in Pomerania (SHIP), 3148 subjects were randomly selected from the population and assessed for a broad range of diseases and environmental/behavioral risk factors. From the complete study group in the age 40 to 60 years, N = 1085 subjects were genotyped for the interleukin-1 genotype composite polymorphism in relation to periodontal parameters. The study objective was to elucidate the gene-environment interaction between the risk factors smoking and IL-1 polymorphism. An increased risk of periodontal disease was found for IL-1 genotype-positive smokers: odds ratio adjusted for age, sex, education, and plaque OR = 2.50 (95% C.I. 1.21 to 5.13; p = 0.013). This was not the case with subjects who never smoked: OR = 1.09 (0.73-1.62; p = 0.676). These results support the hypothesis of gene-environmental interaction in periodontitis.

Dose-effect relation of smoking and the interleukin-1 gene polymorphism in periodontal disease.

BACKGROUND: Periodontitis is a bacterial inflammatory disease leading to attachment loss with the consequence of tooth loss. There exists a multifactorial risk pattern including bacterial challenge, smoking, age, gender, diabetes, and socioeconomic and genetic factors. Smoking has the highest impact on the course of the disease modulated by all the other factors. Here, we report the relationship between smoking and the genetic polymorphism of interleukin-1 (IL-1). METHODS: In a randomly selected population-based study, we genotyped 1,085 test persons for the IL-1 genotype, examined their periodontal status, and assessed their smoking behavior including present and past quality and quantity of smoking. RESULTS: There was a significant dose-effect relationship between the exposure to tobacco smoke and the extent of periodontal disease assessed as attachment loss and tooth loss. Moreover, there was a gene-environmental interaction. Subjects bearing at least one copy of the variant allele 2 at positions IL-1A -889 and IL-1B +3954 (genotype positive) had an enhanced smoking-associated periodontitis risk as compared to their IL-1 genotype-negative counterparts. With genotype-negative non-smokers as a reference, logistic regression resulted in odds ratios of 0.98 (95% confidence interval: 0.83 to 1.14), 2.37 (1.96 to 2.87), and 4.50 (2.30 to 8.82) for genotype-positive non-smokers, genotype-negative smokers, and genotype-positive smokers, respectively. CONCLUSIONS: There is a gene-environmental interaction between smoking and the IL-1 genetic polymorphism. Smokers bearing the genotype-positive IL-1 allele combination have an increased risk of periodontitis. The IL-1 genotype has no influence in non-smokers.

Genetic, psychosocial and clinical factors associated with hippocampal volume in the general population.

The hippocampus--crucial for memory formation, recall and mood regulation--is involved in the pathophysiology of dementia and depressive disorders. Recent genome-wide association studies (GWAS) have identified five genetic loci associated with hippocampal volume (HV). Previous studies have described psychosocial and clinical factors (for example, smoking, type 2 diabetes and hypertension) to have an impact on HV. However, the interplay between genetic, psychosocial and clinical factors on the HV remains unclear. Still, it is likely that genetic variants and clinical or psychosocial factors jointly act in modifying HV; it might be possible they even interact. Knowledge of these factors might help to quantify ones individual risk of or rather resilience against HV loss. We investigated subjects (N=2463; 55.7% women; mean age 53 years) from the Study of Health in Pomerania (SHIP-2; SHIP-TREND-0) who underwent whole-body magnetic resonance imaging (MRI) and genotyping. HVs were estimated with FreeSurfer. For optimal nonlinear model fitting, we used regression analyses with restricted cubic splines. Genetic variants and associated psychosocial or clinical factors were jointly assessed for potential two-way interactions. We observed associations between HV and gender (P<0.0001), age (P<0.0001), body height (P<0.0001), education (P=0.0053), smoking (P=0.0058), diastolic blood pressure (P=0.0211), rs7294919 (P=0.0065), rs17178006 (P=0.0002), rs6581612 (P=0.0036), rs6741949 (P=0.0112) and rs7852872 (P=0.0451). In addition, we found three significant interactions: between rs7294919 and smoking (P=0.0473), rs7294919 and diastolic blood pressure (P=0.0447) and between rs7852872 and rs6581612 (P=0.0114). We suggest that these factors might have a role in the individual susceptibility to hippocampus-associated disorders.

The association between anterior crossbite, deep bite and temporomandibular joint morphology validated by magnetic resonance imaging in an adult non-patient group.

The aim of this study was to determine whether associations exist between anterior edge-to-edge bite, anterior crossbite, deep bite and morphology of the temporomandibular joint (TMJ) in the vertical dimension, evaluated by magnetic resonance imaging (MRI) in adults. A total of 148 subjects (90 females, 58 males) were selected from the cross-sectional epidemiological population-based study "Study of Health in Pomerania" (SHIP) for this evaluation. In each person a clinical orthodontical examination was performed. Four linear measurements and one ratio from MRI scans of the TMJs were evaluated. To estimate the effects of anterior edge-to-edge bite, anterior crossbite and deep bite on TMJ variables, linear regression was applied. (Analyses were adjusted for sex, age, school education, and orthodontic treatment.) Anterior edge-to-edge-bite/crossbite had shorter mean eminence heights (eh) on both joint sides (p<0.01). In deep bite without gingival contact the postglenoid process height (pgph) decreased significantly in left joints (p=0.018) and there was a tendency to a decrease in right joints (p=0.059). The ratio between eminence height and postglenoid process height (eh/pgph) was increased on both left (p<0.001) and right (p=0.002) joints. In conclusion, anterior edge-to-edge-bite/crossbite is connected to a reduced eminence height and deep bite without gingival contact with an increased ratio between eminence height and postglenoid process height. Therefore the condylar path in the anterior edge-to-edge bite and crossbite cases can be interpreted to be reduced and in the deep bite cases without gingival contact to be steepened.

The effect of catechol-O-methyltransferase polymorphisms on pain is modified by depressive symptoms.

BACKGROUND: Variations within the catechol-O-methyltransferase (COMT) gene have been associated with pain severity in temporomandibular disorders (TMDs). Psychological factors such as personal conflicts, life stress and depression, are well known to be associated with onset, severity and chronicity of pain disorders. AIM: We hypothesized that the relationship between the COMT gene and TMD pain is modified by depressive symptoms. METHODS: Cross-sectional data from the population-based Study of Health in Pomerania (SHIP) in Germany were used to estimate additive interactions between depressive symptoms and 22 single-nucleotide polymorphisms (SNPs) of the COMT gene and the neighbouring thioredoxin reductase 2 (TXNRD2) gene on TMD pain. All participants were Caucasian subjects from a rural area in Northeast Germany. After exclusion of 79 subjects with antidepressant medication, 29.9% of the remaining 3904 subjects reported lifetime depressive symptoms. TMD pain was assessed by a standardized clinical examination. Among various TMD signs, only those that assessed muscle or joint pain on palpation were used as recommended. RESULTS: Six SNPs from the first of three COMT/TXNRD2 haploblocks interacted with depressive symptoms on TMD pain (smallest p-value: 2.7 × 10(-10) ). In subjects without depressive symptoms, rs5993882 was identified as the SNP most likely to be related to TMD pain. In subjects with symptoms of depression, rs1544325 was the corresponding top COMT SNP. CONCLUSIONS: Our results indicate that variants within the COMT gene are associated with pain perception. However, this association is highly moderated by the absence or presence of lifetime depressive symptoms.

The factors associated with body mass index in adults from the study of health in Pomerania (SHIP-0), Germany.

OBJECTIVE: To investigate the relation between dental status, BMI and systemic diseases and to evaluate the risk factors for having a higher BMI. MATERIALS AND METHODS: Apopulation based cross sectional study of 6248 subjects aged 18-80 years (response of 68.8%, n=4310) was conducted in the Study of Health in Pomerania (SHIP-0). Socio-demographic, medical and oral health information was recorded by 5 dentists at two similarly equipped medical/dental services in the cities of Greifswald and Stralsund. Bivariate statistics, multivariate statistics, linear and logistic regression models were performed to assess the relationship between following covariates: gender, educational level, family status, social activities, income, quality of life (SF-12), smoking, alcohol abuse, diabetes, renal disease, high blood pressure, dental status and high physical activity. RESULTS: Significant risk factors for subjects having a higher BMI were: high blood pressure (OR=2.28), diabetes (OR=2.10), educational level (low: OR=1.49; medium OR=1.27), male (OR=1.32) and former smoker (OR=1.20). whereas young age, being single and being dentate (natural teeth, replaced teeth or fixed teeth) was shown to be protective for having a "high" BMI. CONCLUSION: The most important predictors of BMI were shown to be social and medical factors. Dental factors are most significantly influenced by social factors and also exhibit an important impact on BMI.

The peritoneal explant test for evaluating tissue tolerance to mouthrinses.

The tissue cultures of explants of neonatal rat peritoneum have been demonstrated to be a sensitive test for tissue compatibility with wound antiseptics. The present study investigated the suitability of this method to assess the relative toxicity of mouthrinses to tissue. Mouthrinses containing 0.1% chlorhexidine (Chlorhexamed Fluid 0.1%) (A), 0.3% triclosan (Colgate) (B), essential oil in ethanolic solution (Listerine) (C), and amine/stannous fluoride (Meridol) (D) were tested at use concentration and in dilutions of 10, 1, and 0.1% with exposure times of 1, 10, and 30 min, respectively. The mouthrinses (test) and Ringer's solutions (control) were applied to opened rat peritoneum. After thorough irrigation with Ringer's solution, a piece of peritoneum was removed and 1 x 1 mm explants were cut. The explants were cultivated with a bovine serum culture medium in 24-well plates at 37 degrees C in a CO2 incubator (95% air, 5% CO2). After 10 days, the tissue proliferation for the explants was assessed by a stereo microscope at 10x magnification after ethanol fixing and hemalaun staining. With 24 grafts per test, the proliferation rate was calculated relative to a control, which was run for each mouthrinse and concentration/time combination. Data were analyzed using ANOVA (SPSS 11.0) and post-hoc paired t test. Statistical significance of all correlations was tested by setting the significance level at p < 0.05. At most concentrations, D caused significantly less tissue damage than A or B. There was no difference between C and A or C and B at 100%. However, the toxicity of C was significantly less than A or B at 10, 1, and 0.1%. C and D behaved similarly except for the 10% (30 min) and the 1% (10 min) solutions in which C was significantly less toxic. We concluded that the rat peritoneum explant test was demonstrated to be a sensitive test to assess the relative toxicity of mouthrinses to tissue.