Clinical characteristics and prognostic factors of cracked teeth: A retrospective cohort study

Cracked teeth syndrome is a common tooth hard tissue injury, often combined with pulp and/or periodontal symptoms.This study aimed to investigate the clinical characteristics and progression patterns of such teeth and to identify independent factors influencing the one-year success rate of early intervention, providing a theoretical basis for precise treatment strategies.

We conducted a retrospective cohort study of 561 patients diagnosed with cracked teeth at Taihe Hospital between June 1, 2021, and December 31, 2024. Data collected included age, sex, tooth position, crack direction, symptom duration, and treatment modality. The primary outcome at one-year follow-up was "treatment success," defined as normal occlusal function, absence of symptoms, and no tooth mobility. A subgroup of 67 patients with early-stage cracked teeth (treated with either composite resin restoration or full-coverage crowns) was further analyzed using bivariate (Chi-square or Fisher's exact test) and Multivariable logistic regression to identify prognostic factors.

Among the 561 patients (309 males, 55.08%; 252 females, 44.92%), the 40-49-year age group was most frequently affected (29.59%). Maxillary first molars were the most commonly involved teeth (37.01%), with occlusal discomfort being the predominant symptom (72.73%). Cracks involving the distal marginal ridge were the most frequent (39.45%) and were associated with the highest failure rate (16.81%, χ²=16.285, P< 0.05). Two critical periods for progression to pulpitis were observed: 0-1 month (48.97%) and 3-6 months (27.84%). For early-stage teeth, the success rate of full-coverage crowns (78.05%) was higher than composite resin (50.00%, χ²=5.676, P<0.05). Multivariable analysis confirmed full-coverage crowns (OR=5.57, 95%CI=1.44-21.56, P< 0.05) and normal pulp status (OR=4.52, 95%CI=1.23-16.69, P<0.05) as independent protective factors. Longer durations of occlusal discomfort were significantly associated with the development of pulpitis.

This study demonstrates that the distal marginal ridge is the most common site for cracks in cracked teeth and is associated with a poorer prognosis. Two critical periods for the progression from occlusal discomfort to pulpitis were identified: 0-1 month and 3-6 months. Multivariable analysis identified the type of restoration, pulp status, and duration of occlusal discomfort as key factors influencing the one-year success rate of early cracked tooth treatment.

The findings may support earlier, more precise intervention to preserve pulp health and improve long-term outcomes.