The Effect of Bitewing Radiography on Outcomes and Costs of Treating Caries in Permanent Teeth

Background: Visual-tactile examination is the primary method to detect and classify caries lesions, but bitewing radiography may complement it when examining approximal surfaces of posterior teeth. Bitewing radiography is used in 30% of periodic oral examinations in Finnish communal dental clinics, but the frequency varies greatly among dentists. The effect of bitewing radiography on caries treatment, patient-important outcomes, and cost-effectiveness has not been assessed in randomized controlled trials among adults. The only comparable trial, performed among 3-6-year-old children, found that bitewing radiography brought more harm than benefits. As the dentition and caries expression of adults differ substantially from those of young children, dedicated evidence for adults is needed.

Aim: To conduct a randomized controlled trial assessing patient-important outcomes resulting from including bitewing radiography in caries diagnostics in Finnish young adults.

Methods: This single-center, two-arm RCT follows SPIRIT and CONSORT guidelines and is a substudy of the ongoing PANIC study. Close to 500 PANIC participants will be invited to the 20-year follow-up oral examination starting in spring 2027, when they are about 27 years old. All assenting participants will undergo a strictly predefined visual-tactile examination by two calibrated dentists, covering masticatory system, mucosa, periodontium, dentition, and occlusion.

Allocation: About 250 participants are expected to attend, most of them eligible. Eligible participants will be randomized 1:1 using stratified block randomization (block sizes 4-6) at sealedenvelope.com to either receive a further bitewing radiographic examination or not. The random sequence will be generated by a researcher not involved in the examinations.

The bitewing radiography includes bitewing radiographs from both sides of the jaw, their review in a dark room with dedicated software and an optimized screen, and a second clinical examination for surfaces where the first visual-tactile examination and radiographic examination disagree. Radiographs will be examined by both the examining dentist and a dentist specializing in dental radiology. They will be calibrated before the start of the examinations.

Treatment plan: All participants will receive a structured treatment plan following pre-specified indications for treatment. All participants will be recommended daily tooth brushing. Indications for caries treatment are a) caries lesions that are not cleanable due to undermining cavitation, b) symptomatic caries lesions, c) caries lesions that have caused so much tooth substance loss that the tooth no longer is in occlusion, d) caries lesions causing a significant aesthetic impairment and e) caries lesions that threaten tooth vitality. The treatment plans for masticatory system, mucosa, periodontium and occlusion follow Finnish Current Care Guidelines. The treating dentist will be able to review the bitewing radiographs that have been taken in the baseline examination or take bitewing radiographs herself/himself. The treatment provided will be followed using patient records.

Follow-up: All participants will be followed electronically using national and local patient registers. Treatments will be categorized using standardized national codes maintained by the National Institute for Health and Welfare.

Sample size: No prior data are available for a formal sample size calculation; a convenience sample of the ~250 expected attendees will be used.

Statistical analyses: Effects on outcomes will be analyzed using suitable linear or generalized linear models, adjusting for relevant baseline data. Examination step times and planned treatments will be compared across arms. Cost-effectiveness will be evaluated by comparing costs and outcomes across arms. Analysts will be blinded to allocation. A detailed statistical analysis plan will be finalized after trial completion and before unblinding.