# Risk Factors Associated with Cusp Fractures in Posterior Permanent Tenth--A Cross-Sectional Study
## 3 Results  
### Descriptive Analysis and Frequencies Comparison  
One hundred and seventy-seven (177) patients from 16 to 66 years old (\(\pm\)41.56), from 1998 to 2016, were included in this study.  
Eighty per cent of cases, approximately, presented the fractured fragment still in position at examination, or it was possible to identify the cusp detachment, discarding cases with cohesive/adhesive fractures of restorations or caries. Data regarding relative frequencies in each category are shown in Table 1 and Figures 1 and 2. For each variable, similar letters among the levels indicate absence of statistical difference (\(p>0.05\)). Significance statistical differences were observed in each category for the variables: gender, age, tooth type, fracture type, cuspids role, fracture height, involved surfaces, number of cuspids, presence of restorations, isthmus, restorative material, endodontic treatment, and symptomatology. Overall, patients did not show symptoms before the injury. Fractures were more common in teeth where the restoration had an isthmus wider than 1/3 of the intercuspid distance and/or involved more than 3 restored surfaces. Non-functional cusps presented a higher fracture frequency in comparison with functional cusps, and lingual cusps presented a higher fracture frequency in comparison with buccal cusps. No teeth that presented mobility more than score A or pockets \(\geq\) 3 mm were included. To improve our analysis, from 2010, 67 patients answered about their functional habits (bruxism/clinch) according to Table 1. However, representing a smaller sample and reduced frequency of patients with bruxism/clench (20%), these data were not analyzed with uni- and multivariate analyzes.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Variable** & **Level** & **Absolute Frequency** & **Relative Frequency (\%)** \\ \hline \multirow{3}{*}{Gender} & Male & 109 & 61.6 \({}^{\text{a}}\) \\  & Female & 68 & 38.4 \({}^{\text{b}}\) \\ \hline \multirow{6}{*}{Age} & \textless{}20 & 7 & 4.0 \({}^{\text{d}}\) \\  & 20–30 & 25 & 14.1 \({}^{\text{c}}\) \\  & 31–40 & 44 & 24.9 \({}^{\text{ab}}\) \\  & 41–50 & 58 & 32.8 \({}^{\text{a}}\) \\  & 51–60 & 34 & 19.2 \({}^{\text{bc}}\) \\  & \textgreater{}60 & 9 & 5.1 \({}^{\text{d}}\) \\ \hline \multirow{6}{*}{Age} & 14 & 14 & 7.9 \({}^{\text{abcd}}\) \\  & 15 & 8 & 4.5 \({}^{\text{bcdef}}\) \\  & 16 & 20 & 11.3 \({}^{\text{ab}}\) \\  & 17 & 2 & 1.3 \({}^{\text{ef}}\) \\  & 24 & 6 & 3.4 \({}^{\text{cdef}}\) \\  & 25 & 11 & 6.2 \({}^{\text{abde}}\) \\  & 26 & 18 & 10.2 \({}^{\text{abc}}\) \\ \multirow{2}{*}{Tooth number} & 27 & 8 & 4.5 \({}^{\text{abedef}}\) \\  & 34 & 4 & 2.3 \({}^{\text{def}}\) \\  & 35 & 2 & 1.1 \({}^{\text{ef}}\) \\  & 36 & 19 & 10.7 \({}^{\text{abc}}\) \\  & 37 & 18 & 10.2 \({}^{\text{abc}}\) \\  & 44 & 1 & 0.6 \({}^{\text{f}}\) \\  & 45 & 2 & 1.1 \({}^{\text{ef}}\) \\  & 46 & 28 & 15.8 \({}^{\text{a}}\) \\  & 47 & 16 & 9.0 \({}^{\text{abc}}\) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Absolute and relative frequency of general variables of sample.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Variable** & **Level** & **Absolute Frequency** & **Relative Frequency (\%)** \\ \hline \multirow{3}{*}{Tooth type} & Maximillary premolar & 39 & 22.0 b  \\  & Maximillary molar & 48 & 27.1 b  \\  & Mandibular premolar & 9 & 5.1 c  \\  & Mandibular molar & 81 & 45.8 a  \\ \hline \multirow{3}{*}{Arch} & Mandibular & 91 & 51.4 a  \\  & Maximillary & 86 & 48.6 a  \\ \hline \multirow{3}{*}{Bruxism/Clinch} & Yes & 14 & 20.9 a  \\  & No & 47 & 70.1 b  \\  & Unknown & 6 & 8.9 a  \\ \hline \hline \end{tabular}  
* Groups with the same superscript lowercase letters indicate absence of statistical difference (\(\alpha=0.05\); [PERSON] exact test).  
\end{table}
Table 1: _Cont._  
Figure 1: Relative frequency of variables related to teeth characteristics. Groups with the same lowercase letters indicate absence of statistical difference (\(\alpha=0.05\); [PERSON] exact test).