Data collection
Caries, carious lesion, radiolucency, tooth
CARIES, BITE, IMPACTION, PLAQUE
The baseline data on the child’s demographics (age and gender), family’s socioeconomic background (parents’ education level and family incomes), and child’s oral health related behaviors (tooth brushing, use of fluoride toothpaste, and cariogenic snack consumption) were collected from the parents using a structured questionnaire.Clinical examinations at baseline and follow-up visits were performed by a single examiner (P.S) trained and calibrated by dental specialists in dental public health (D.D) and pediatric dentistry (V.J) until the weighted kappa values of inter- and intra-reliability were ≥ 0.8 each. The examiner was blinded to the allocation groups. The clinical examinations were conducted in the school-based setting using World Health Organization (WHO) CPI periodontal probes with an LED dental mouth mirror. The participants were examined in the supine position on a mobile dental unit. The tooth/surface status was recorded as sound, decayed, missing, and filled (dmft/dmfs) based on WHO criteria. The oral cleanliness status was assessed using the simplified oral hygiene index on the buccal or lingual surfaces of 6 index teeth (55, 51, 65, 71, 75, and 85). The plaque score was measured on a scale of 0–3. An average high score indicated poor dental hygiene. The presence of food impaction and contact area characteristics (open or closed) of each proximal surface were also recorded.Bitewing radiographic images were taken on the posterior teeth with closed contact surfaces, at the initial examination and at the 6-, 12-, and 18-month follow-ups. An experienced radiology technician conducted the radiographic imaging using size 0 digital film, a film holder, and a portable digital x-ray machine (EzRay Air: VEX-P300; 65 kV and 2.5 mA, exposure time 0.38s) with a standardized technique. Bite position was recorded and used for each follow-up visit. Both technician and participants wore lead aprons and thyroid shields while taking the radiographs. The digital films were processed automatically (VistaScan Mini Easy, Dürr Dental, Germany). The bitewing radiographic images were sent anonymously to two independent dentists trained and calibrated by a pediatric dental specialist (V.J) until inter- and intra-reliability were reached (≥ 0.8 for each dentist). The two examiners viewed the radiographic images independently via DBSWIN imaging software (Dürr Dental, Germany) and scored approximal surface characteristics accordingly: (sound) no radiolucency, (RA1) radiolucency confined to the outer half of enamel, (RA2) radiolucency that reached the inner half of the enamel or to the enamel-dentin junction, (RA3) radiolucency that reached the outer third of the dentin, (RB4) radiolucency that reached the middle third of dentin, (RC5) radiolucency that reached the inner third of dentin, (RC6) radiolucency approaching the pulp, (F) filled surface, and (E) extracted tooth. The examiners were requested to re-evaluate the surfaces with discrepancy scores. If disagreement persisted, a discussion was held until agreement was reached. Caries development was determined when the recruited approximal surface had a carious lesion at the moderate stage (RB4) or extensive stages (RC5, RC6, F, E) at the follow-up visits.After examination, the parents/guardians of all participants received a summary of their children’s oral health status and treatment needs, leaflets of oral health education, as well as a referral letter for preventive and operative treatment.