J Oral Maxillofac Surg 64:652-658, 2006 Reliability of Third Molar Probing Measures and the Systemic Impact of Third Molar Periodontal Pathology Kevin L. Moss,* Sally Mauriello, BS, MEd, EdD,† Andrew T. Ruvo, DMD, MD,‡ Steven Offenbacher, DDS, PhD,§ Raymond P. White, Jr, DDS, PhD, and James D. Beck, PhD¶ Purpose: This study examined the reliability of assessing clinical periodontal measures on third molars, and the association between oral inflammation with periodontal pathology including third molars, and systemic inflammation including negative obstetric outcomes. Patients and Methods: Reliability of third molar probing depth (PD) was assessed for 41 patients by trained examiners. The data for the association between oral inflammation with periodontal pathology and systemic outcomes were derived from an IRB-approved study, “Oral Conditions and Pregnancy.” Full mouth periodontal exams including third molars were conducted at less than 24 weeks of pregnancy. Periodontal status, moderate/severe periodontal disease (15 or more sites PD 4 mm) was considered as a possible predictor of systemic inflammation and pre-term birth. The upper quartile of the extent of PD for third molars alone (PD 4 mm) also was considered as a possible exposure variable for the same outcomes. Chi-square and t tests were used to determine statistical significance (0.05). Significant predictor variables were included in multivariate models. Unconditional logistic multivariate models were used to derive odds ratios (OR) and 95% confidence intervals (CI). Results: Reliability of PD within 1 mm was excellent, and similar for third molars and non-third molars. Data from 1,020 obstetric patients were available for analysis. Eighteen percent of the patients delivered preterm, at less than 37 weeks. Having moderate/severe periodontal disease excluding third molars, was significantly associated with preterm birth (P = .008). Results were more significant if third molars were included (P = .0005). With multivariate models moderate/severe periodontal disease at enrollment including third molar PD, was associated with preterm birth (OR, 1.7; 95% CI, 1.1, 2.6). If only the extent of third molar PD was considered, odds also were increased for preterm birth (OR, 2.4; 95% CI, 1.1, 5.2). If only the extent of third molar PD was considered at enrollment, odds were increased for serum markers of systemic inflammation, elevated serum CRP, and oxidative stress, 8-isoPGF 2 . Conclusions: Dental examiners could reliably assess clinical periodontal measures on third molars. Third molars should be included in studies of systemic outcomes associated with oral inflammation. Women of child-bearing age should be made aware of the systemic risks of oral inflammation with third molar periodontal pathology. © 2006 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 64:652-658, 2006 Most often clinical trials assessing the extent of peri- odontal pathology do not include third molars. For example, Haffjee et al 1 studied the association be- tween clinical measures of periodontal disease and Received from the School of Dentistry, University of North Caro- lina, Chapel Hill, NC. *Research Applications Specialist, Department of Dental Ecology. †Associate Professor, Department of Dental Ecology. ‡Senior Resident, Department of Oral and Maxillofacial Surgery. §OraPharma Distinguished Professor, Department of Periodon- tology. Dalton L. McMichael Distinguished Professor, Department of Oral and Maxillofacial Surgery. ¶Distinguished Kenan Professor, Department of Dental Ecology. This study was supported and funded by NIH RO-1-DE-12453, NIH RR-00046, AAOMS, OMFS Foundation, and the Dental Founda- tion of North Carolina. Address correspondence and reprint requests to Dr White: School of Dentistry, Dept. of Oral and Maxillofacial Surgery, Uni- versity of North Carolina, CB 7450, Chapel Hill, NC 27599-7450; e-mail: ray_white@dentistry.unc.edu © 2006 American Association of Oral and Maxillofacial Surgeons 0278-2391/06/6404-0013$32.00/0 doi:10.1016/j.joms.2005.12.012 652