Contrasting Patterns for Missing Third Molars in the United States and Sweden.

PURPOSE: The purpose of this study was to compare the prevalence of third molars from the US National Health and Nutrition Examination Survey (NHANES) and the Swedish survey. MATERIALS AND METHODS: This cross-sectional study involved the comparison of the only published data on third molar prevalence. The number of visible third molars in the NHANES of 2011 through 2012 were assessed in nonclinical settings by trained, calibrated dental hygienists and reported by age decade (approximately 5,000 patients). Similar data were reported for the Swedish population with data collected in clinical settings (approximately 700 patients). The primary outcome variable was the number of third molars (0 to 4); the predictor variables were age cohorts (20 to 29 through 70 to 79 yr). Outcome data were reported with descriptive statistics. RESULTS: In the youngest cohort (20 to 29 yr), having no visible third molars was more likely in the US population than in the Swedish population (47 vs 2%, respectively). By 50 to 59 years, outcomes for no third molars were similar in the United States and Sweden (53 and 57%, respectively). CONCLUSION: The presence or absence of third molars reported from the US and Swedish populations presented contrasting patterns, particularly in the younger cohorts. More comprehensive and detailed data are required in future surveys as population studies on third molars become more important for clinicians and other stakeholders.

Special Contribution: Third Molar Clinical Trials Annotated Bibliography.

PURPOSE: To provide clinicians with an annotated bibliography of published articles from research funded externally by the Oral and Maxillofacial Surgery Foundation, spanning 1996 to 2015, addressing the topic of third molar management. MATERIALS AND METHODS: A brief summary for each article was generated by the respective authors. RESULTS: The complete annotated bibliography generated by the authors is included in the Appendix. CONCLUSION: The annotated bibliography provides clinicians and other interested individuals with a summary of current literature emanating from clinical studies on third molar topics.

Prevalence of Visible Third Molars in the United States Population: How Many Individuals Have Third Molars?

PURPOSE: To determine the prevalence of third molars in the US population and to report the differences in prevalence of visible third molars in the most recent National Health and Nutrition Examination Survey (NHANES) population of 2011 through 2012 by participant, jaw, and demographics. MATERIALS AND METHODS: The number of visible third molars in the NHANES data was assessed in nonclinical settings by trained, calibrated dental hygienists by decade of age beginning in the 20- to 29-year-old cohort through the 70- to 79-year-old cohort. Cross-sectional analyses of third molar data were conducted by the authors from the NHANES databases of 2001 through 2002, 2009 through 2010, and 2011 through 2012 to compare data for similarity of outcomes on third molar prevalence in the US population. Outcomes on third molar prevalence also were assessed from the NHANES of 2011 through 2012 by participant, jaw, and demographics: gender, race or ethnicity (Caucasian, African American, other), and education (less than high school, high school graduate, some college, college graduate). RESULTS: Data on the mean number of third molars from NHANES of 2001 through 2002, 2009 through 2010, and 2011 through 2012 were similar. The number of visible third molars in the NHANES of 2011 through 2012 decreased progressively from a mean of 1.48 in the 20- to 29-year-old cohort to 0.81 in the 60- to 69-year-old cohort, No visible third molars were observed in 47% of the 20- to 29-year-old cohort compared with 53% in the 50- to 59-year-old cohort. Participants who were male, non-Caucasian, and had less than a high school education were more likely to have a visible third molar in all age cohorts. No data were collected by NHANES examiners to determine why third molars were absent. CONCLUSION: Third molar prevalence did not appear to differ in the US population during the first decade of the 21st century. Numbers of visible third molars, prevalent in young adults, decreased progressively through each successive age cohort. Demographic differences exist for prevalence of third molars in the US population.

Mechanical debridement of subgingival biofilm in participants with asymptomatic third molars does not reduce deeper probing depths in the molar regions of the mouth.

PURPOSE: To assess the impact of mechanical debridement of subgingival biofilm on periodontal outcomes in adolescents and young adults with asymptomatic third molars. METHODS: Healthy participants with 4 asymptomatic third molars were enrolled in an institutional review board-approved longitudinal study. Clinical data were collected at enrollment and at follow-up visits. Full-mouth periodontal probing, 6 sites per tooth, was assessed as a measure of clinical periodontal status. At enrollment, all participants had dental prophylaxis after data collection, which included removal of subgingival biofilm; this was repeated annually. The primary outcome measures were the comparison from baseline to follow-up 2 years after enrollment of participants' periodontal probing depths for third molars and first/second molars. In addition, a comparison of extent scores at baseline to follow-up 2 years after enrollment for periodontal probing sites of at least 4 mm was performed for the same molar regions of the mouth. Changes over time in clinical periodontal status from enrollment to the follow-up at least 2 years later were analyzed with Mantel-Haenszel row mean score statistics. The level of significance was set at P < .05. RESULTS: The median follow-up from entry to the study was 2.2 years (interquartile range, 2.0-2.8 years) for 262 participants who averaged 27.7 years of age (SD, 1.2 years); 53% were female participants, and 81% were white. Most participants (90%) were educated beyond high school. On the basis of periodontal probing depths, participants' clinical periodontal status did not differ from enrollment to follow-up. CONCLUSIONS: Dental prophylaxis at yearly intervals in participants with asymptomatic third molars, which included mechanical removal of subgingival biofilm, had minimal or no impact on reducing deeper probing depths, clinical indicators of periodontal pathology in young adults.

Risk factors for third molar occlusal caries: a longitudinal clinical investigation.

PURPOSE: To study the third molar occlusal caries incidence and identify related patient-level sociodemographic, dental behavior, and clinical risk factors. PATIENTS AND METHODS: A prospective cohort study was used to study caries risk (crude increment and incidence rate) on retained and erupted to the occlusal plane third molars among a moderate-size (n = 215) group of healthy (American Society of Anesthesiologists class I and II) young adults (median age, 26 years) followed up for a mean of 4.6 years. Clinical data were gathered by calibrated examiners using visual-tactile and radiographic diagnostic methods on all molar teeth. The covariates included age at enrollment, gender, race, income, education, frequency of dental visits, oral hygiene behaviors, and smoking. Summary statistics and visual methods were used for data description. The analyses relied on bivariate and multivariate methods using generalized estimating equations, extensions of Poisson modeling. RESULTS: Of the 215 patients, 33% developed occlusal caries on 1 or more retained third molars. The incidence rate was 0.11 (95% confidence interval 0.09 to 0.13) third molar "increments"/person-year. Those with any molar caries at baseline were 80% more likely to have a new third molar caries lesion at the end of follow-up compared with those with caries-free molars (prevalence ratio, 1.80; 95% confidence interval, 1.08 to 3.00). The third molar caries rate was halved for every approximately 9 years of the subjects' baseline age. Favorable oral hygiene behaviors and better socioeconomic status were associated with decreased caries risk. However, independent of other covariates, smoking increased the third molar caries risk twofold. CONCLUSIONS: Younger patients from lower socioeconomic strata, smokers, and those with poor oral hygiene behavior are at an increased risk of occlusal caries development on their retained third molars.

Changes over time in the prevalence of caries experience or periodontal pathology on third molars in young adults.

PURPOSE: To assess the prevalence of caries experience and periodontal pathology on third molar teeth compared with first and second molars and teeth more anterior from subjects who had data collected over time in a longitudinal clinical study. PATIENTS AND METHODS: Healthy subjects with 4 asymptomatic third molars and data for at least 4 years after enrollment were included in these analyses. The presence or absence of caries experience on the occlusal surface of the third molars and any surface of the first or second molars was assessed using a visual-tactile caries examination. Full mouth periodontal probing, 6 sites per tooth, was conducted as a measure of clinical periodontal status. The primary outcome measures were at least 1 periodontal probing depth of at least 4 mm versus none, and caries experience versus no caries experience. The prevalence of caries experience and periodontal pathologic findings at follow-up and the relationship of the occurrence between the third molars and teeth more anterior in the mouth were examined using McNemar's statistics. RESULTS: The follow-up was a median of 6.9 years (interquartile range 4.6 to 7.7 years) for 179 subjects, with a mean age of 29 years. More subjects were female (54%) and white (80%). At follow-up, 85% of the subjects had caries experience detected on the first or second molars, and only 50% had a third molar affected. In contrast, at follow-up, the presence of at least 1 periodontal probing depth of at least 4 mm was marginally more prevalent on the third molars than on the first or second molars (56% and 50%, respectively). Fewer subjects had third molars free of caries experience and periodontal pathology at follow-up compared with at enrollment (28% versus 38%, respectively). CONCLUSIONS: The prevalence of both third molar caries experience and third molar periodontal pathology increased from baseline to the follow-up examination. At follow-up, the prevalence of caries experience was greater on the first or second molars than on the third molars, and periodontal pathology were greater on the third molars than on the more anterior teeth.

Prevalence of third molars with caries experience or periodontal pathology in young adults.

PURPOSE: We assessed the prevalence of caries experience and periodontal pathology on asymptomatic third molars in young adults. SUBJECTS AND METHODS: Healthy subjects with 4 asymptomatic third molars were enrolled in an institutional review board-approved study during a 5-year period. Full mouth periodontal probing, 6 sites per tooth, was the measure of clinical periodontal status. The presence or absence of occlusal caries experience (carious lesions or restorations, including sealants) on third molars and on any surface of the first and second molars were assessed using a visual-tactile examination and panoramic radiographs. The primary outcome measures were at least 1 periodontal probing depth of at least 4 mm versus none and caries experience versus no caries experience. RESULTS: The data were analyzed from 409 subjects, who averaged 25 years old. More subjects were female (53%) and white (76%). More subjects had at least 1 periodontal probing depth of 4 mm or deeper on a third molar (55%) than on the distal of a second molar (46%). These findings were more likely to be detected around a third molar in subjects with all third molars at the occlusal plane (72%) than in subjects with at least one third molar below (33%). Overall, fewer subjects were affected by third molar caries experience than first or second molars (24% vs 73%, respectively). Of the subset of subjects with all four third molars at the occlusal plane, 26% were affected by both third molar periodontal pathology and caries experience and 16% were caries and periodontal pathology free. CONCLUSIONS: In these cross-sectional analyses, periodontal pathology was detected more frequently on third molars than on first and second molars and caries experience was detected more frequently on first and second molars than on third molars.

Prevalence of visible third molars with caries experience or periodontal pathology in middle-aged and older Americans.

PURPOSE: To assess the prevalence of periodontal pathology and caries experience in visible third molars, as well as the relationship of these findings to periodontal pathology and caries experience in teeth more anterior in the mouth. PATIENTS AND METHODS: Data were from 6,793 Dental Atherosclerosis Risk in Communities participants who underwent a clinical examination for periodontal disease and coronal caries experience and who retained at least 1 visible third molar. Outcome variables were the detection of periodontal pathology or coronal caries experience on visible third molars and on teeth more anterior in the mouth (non-third molars). Periodontal probing depths at least 4 mm (PD4+) and clinical attachment levels at least 3 mm (CAL3+) were indicator variables for periodontal pathology. At least 1 carious/decayed coronal surface or filled coronal surface was an indicator variable for caries experience. Outcomes for third molar and non-third molar teeth were compared by descriptive statistics and χ(2) tests with statistical significance set at P < .05. RESULTS: A third of the 6,793 Dental Atherosclerosis Risk in Communities subjects, who averaged 62 years of age, had at least 1 visible third molar. Subjects were more likely to have at least 1 third molar CAL3+ as compared with at least 1 third molar PD4+: 78% versus 61%. PD4+ and CAL3+ were significantly more prevalent among non-third molars as compared with third molars (P < .01). Most subjects, 73%, had restorations on visible third molars and non-third molars, and over two-thirds of subjects had a visible third molar with caries experience and periodontal pathology. Fewer than 2% of subjects had third molars free of caries experience or periodontal pathology. CONCLUSIONS: Most subjects had clinical evidence of caries experience or periodontal pathology on visible third molars; few subjects had visible third molars that were disease free. Subjects with periodontal pathology or caries experience on third molars were significantly more likely to have these findings detected on teeth more anterior in the mouth.

Visible third molars as risk indicator for increased periodontal probing depth.

PURPOSE: To assess the relationship between visible third molars and the periodontal status of teeth more anterior in the mouth from reports that included periodontal probing data for all teeth. MATERIALS AND METHODS: Each of 4 reports that included periodontal probing data, 6 probing sites for all teeth, including third molars collected by trained, clinician examiners, were briefly summarized. The design, strengths, and weaknesses of each of the 4 studies were compared and summarized. A Forest plot was used to combine the findings from the 4 studies comparing the mean second molar probing depth differences in mm by the presence of at least 1 visible third molar or no visible third molar. RESULTS: A review of the data from 4 reports, 1 from middle-age adults and 3 from young adults, suggested an association between the visible presence of a third molar and increased periodontal probing depths on teeth more anterior in the mouth, predominately the first and second molars. Coupled with the probing depth around the third molars, the result was an expanded surface area at the biofilm-gingival interface. CONCLUSIONS: Although all those with retained third molars are not at increased risk, the summary data we have reported suggest that those with a visible third molar are more likely to have greater periodontal probing depths overall, particularly on second molars, and a greater surface area of the biofilm-gingival interface compared with those with no visible third molar.

Third molar caries experience in middle-aged and older Americans: a prevalence study.

PURPOSE: To assess the prevalence of third molar caries experience in a middle-aged and older population and the relationship of these findings to caries experience in teeth more anterior in the mouth. PATIENTS AND METHODS: Data from 6,550 Dental Atherosclerosis Risk in Communities study participants aged 52 to 74 years who underwent a clinical examination for coronal caries experience were available for these analyses. Subjects with visible third molars (N = 2,003) were divided based on third molar coronal caries experience on at least 1 third molar: no carious/decayed coronal surface (DS) or at least 1 coronal DS and no filled coronal surface (FS) or at least 1 coronal FS. Coronal DS and FS were also calculated for more anterior teeth. Covariates included ethnicity, gender, age, body mass index, education, income, smoking status, and diabetes diagnosis. Subject level outcomes for third molar and more anterior teeth were compared by descriptive statistics and chi(2) or t tests with statistical significance set at P less than .05. Multivariate modeling was performed to adjust outcome variables for covariates. RESULTS: Third molar caries experience was detected in 77% of subjects and was significantly associated with caries experience in more anterior teeth and white race (P < .01). Caries experience was detected in only third molars in 1% of subjects, and 1% of subjects were caries free. Subjects with less education (20%) and lower income (19%) were significantly more likely to have DS detected compared with subjects with more education (6%) and higher income (5%) (P < .01). Conversely, subjects with more education (75%) and higher income (77%) were significantly more likely to have FS detected compared with subjects with less education (55%) and lower income (60%) (P < .01). CONCLUSIONS: Third molar coronal caries experience was significantly associated with caries experience in teeth more anterior in the mouth in this middle-aged and older population.

Fructose-induced increases in neonatal rat intestinal fructose transport involve the PI3-kinase/Akt signaling pathway.

Expression of rat glucose transporter-5 (GLUT5) is tightly regulated during development. Expression and activity are low throughout the suckling and weaning stages, but perfusion of the small intestinal lumen with fructose solutions during weaning precociously enhances GLUT5 activity and expression. Little is known, however, about the signal transduction pathways involved in the substrate-induced precocious GLUT5 development. We found that wortmannin and LY-294002, inhibitors of phosphatidylinositol 3-kinase (PI3-kinase) specifically inhibited the increase in fructose uptake rate and brush-border GLUT5 protein abundance but not GLUT5 mRNA abundance. Perfusion of EGF, an activator of PI3-kinase, also resulted in a marked wortmannin-inhibitable increase in fructose uptake. Perfusion of fructose for 4 h increased cytosolic immunostaining of phosphatidylinositol-3,4,5-triphosphate (PIP(3)), the primary product of PI3-kinase, mainly in the mid- to upper-villus regions in which the brush-border membrane also stained strongly with GLUT5. Perfusion of glucose for 4 h had little effect on fructose or glucose uptake and PIP(3) or GLUT5 staining. SH-5, an Akt inhibitor, prevented the increase in fructose uptake and GLUT5 protein induced by fructose solutions, and had no effect on glucose uptake. The PI3-kinase/Akt signaling pathway may be involved in the synthesis and/or recruitment to the brush border of GLUT5 transporters by luminal fructose in the small intestine of weaning rats. Increases in fructose transport during the critical weaning period when rats are shifting to a new diet may be modulated by several signaling pathways whose cross talk during development still needs to be elucidated.