# Risk Factors Associated with Cusp Fractures in Posterior Permanent Tenth--A Cross-Sectional Study
## 2 Materials and Methods  
This study was approved by the Ibirapuera University Ethics Committee (protocol CAAE n\({}^{\circ}\) 56415416.9.0000.5597) and followed the STROBE guidelines for observational studies [25]. All patients received emergency treatment in the presence of pain and then referred to dental specialists (restorative treatment, periodontitis, and/or prosthesis). Patients presented cusp fractures on posterior permanent teeth, clinically assessed up to 7 days after the event; dental treatment requested at two public services (university and public dentistry clinics) was included in this cross-sectional study. One examiner ([PERSON]) collected fracture data (1998-2007); after this (2008-2016), two examiners ([PERSON] and [PERSON]) were individually trained and then calibrated following the assessment of 10 images of cavities and restorations and 10 images of fractured teeth compared to a benchmark examiner. Kappa values were 0.9, and all possible discordances were solved by consensus. Isthmus in cavity preparation was standardised as follows: less than 1/4, between 1/3 and 1/4, and more than 1/3 of the intercuspid distance. The evaluation of the patients was performed independently, and the final result was decided by consensus. Clinical evaluation was made under dental operating light with an oral mirror, a dental probe, and a three-way syringe, and periapical radiographic examination was assessed by the examiners for all the patients. Only one tooth was included per patient. Periodontal condition was based on scores: A--bleeding on probing and/or calculus, B--pocket 4 to 5 mm without recession, and C--pocket 4 to 5 mm with recession or pockets \(\geq\)6 mm [26]. From 2010, self-reported questionnaire about the presence of parafunctional habits (bruxism/clench) was included, based on the international consensus on the assessment of bruxism ([PERSON] et al. 2018) [27]. Data collection was set at a maximum of 7 days after the fracture episode to avoid memory bias and ensure clinical examination fidelity with minimal dental structure modification from the injury event. Thus, inclusion criteria included only patients assessed up to 7 days after presenting complete fractures on molar and/or pre-molar cusps. Patients were excluded when presenting fractured teeth with absence of the antagonist teeth or with a prosthesis (total and/or removable), as well as when already treated. Demographic and clinical data were collected to draw the patient profiles and establish how teeth were affected individually. Hence, a clinical chart including demographic aspects (age/gender); teeth (FDI classification, molar/pre-molar, upper/lower); tooth characteristics (restoration presence and number of involved surfaces, restorative material, endodontic treatment-after periapical radiographic assessment, and cavity width); referred symptoms; fractured cusps characteristics (total/partial, buccal/lingual, sub/supragingival, and functional/non-functional); and fracture cause (food-hard or normal/soft, unknown, or accidental). Third molars were not considered in this study due to their many variations (anodontia and shape, position, and size anomalies). Regarding the height of the cusp fractures, it was considered supragingival when the inferior level of the fracture was up to the height of the free gingival margin and subgingival when the fracture line invaded the intrasulcular/intraosseous space. Regarding the total volume of the cusp, it was called partial cusp fracture when the fragment did not cover this volume, the remainder of which was a part of this cusp. Furthermore, it was considered as a total fracture when it covered the equivalent of the total volume of this cusp. Sample size was calculated with a significance level of 95% and power of 80%. The main outcome for sample size calculation was the difference between the functional cusp fractures and nonfunctional cusp fractures, with the inclusion of 134 teeth being necessary. Data analysis was conducted using Minitab (Minitab Inc., State College, PA, USA).