Root caries risk indicators: a systematic review of risk models.

OBJECTIVE: To identify risk indicators that are associated with root caries incidence in published predictive risk models.
METHODS: Abstracts (n = 472) identified from a MEDLINE, EMBASE, and Cochrane registry search were screened independently by two investigators to exclude articles not in English (n = 39), published prior to 1970 (none), or containing no information on either root caries incidence, risk indicators, or risk models (n = 209). A full-article duplicate review of the remaining articles (n = 224) selected those reporting predictive risk models based on original/primary longitudinal root caries incidence studies. The quality of the included articles was assessed based both on selected criteria of methodological standards for observational studies and on the statistical quality of the modeling strategy. Data from these included studies were extracted and compiled into evidence tables, with information about the cohort location, incidence period, sample size, age of the study participants, risk indicators included in the model, root caries incidence, modeling strategy, significant risk indicators/predictors, and parameter estimates and statistical findings.
RESULTS: Thirteen articles were selected for data extraction. The overall quality of the included articles was poor to moderate. Root caries incidence ranged from 12% to 77% (mean ± SD = 45 ± 17%); follow-up time of the published studies was ≤ 10 years (range = 9; median = 3); sample size ranged from 23-723 (mean ± SD = 264 ± 203; median = 261); person-years ranged from 23 to 1540 (mean ± SD = 760 ± 556; median = 746). Variables most frequently tested and significantly associated with root caries incidence were (times tested; % significant; directionality): baseline root caries (12; 58%; positive); number of teeth (7; 71%; three times positive, twice negative), and plaque index (4; 100%; positive). Ninety-two other clinical and nonclinical variables were tested: 27 were tested three times or more and were significant between 9% and 100% of the times tested; and 65 were tested but never significant.
CONCLUSIONS: The root caries incidence indicators/predictors most frequently reported were root caries prevalence at baseline, number of teeth, and plaque index. This finding can guide targeted root caries prevention. There was substantial variation among published models of root caries risk in terms of variable selection, sample size, cohort location, assessment methods, incidence periods, association directionality, and analytical techniques. Future studies should emphasize variables frequently tested and often significant, and validate existing models in independent databases.