## 2 Materials and Methods  
### Design and Settings  
The study examined the medical records of a total of 2372 patients with clefts and 534 healthy individuals. These records were obtained from three medical centers in Poland: Wroclaw Medical University, Poznan Medical University, and Polancia Zdroj Hospital. The research was carried out by two investigators, with [PERSON] serving as the supervisor. The study duration spanned 4 years. Individuals with coexisting malformations and congenital syndromes were excluded from the research, as these conditions could potentially contribute to additional dental malformations. Only complete medical records, including panoramic X-rays for assessing tooth quantity (hypodontia, hyperdontia) and identification of impacted teeth, were considered.  
The study focused exclusively on patients with isolated total clefts of the lip, alveolar bone, and palate. Only individuals who had both panoramic X-rays and dental casts from a similar time frame (with a maximum difference of 3 months between records) were included. Those without panoramic X-rays and/or dental casts were excluded from the research. This qualifying selection was implemented to prevent potential errors where the absence of a tooth bud on a dental cast might not necessarily indicate hypodontia. By eliminating such errors, the study aimed to provide a more accurate representation of the actual prevalence of dental anomalies among the examined patients.  
Among the investigated medical records, cases of left-sided (L-CLP), right-sided (R-CLP), and bilateral (BCLP) clefts were included. The research protocol was approved by the Bioethical Committee of Wroclaw Medical University, Poland (KB--597/2008).  
The research was conducted on patients aged between 7.1 and 20 years, with a mean age of 13.18. This age range was chosen because we specifically selected patients who had not undergone previous treatment with fixed orthodontic appliances and were enrolled in the orthodontic care program for craniofacial deformities. The control group was similarly aged, ranging from 7 to 20 years with a mean age of 13.44. The purpose of selecting a similar age range for the control group was to ensure comparability with the cleft patient group and include random individuals requiring orthodontic treatment.  
Based on the selection criteria, the study included a total of 154 patients with clefts and 151 individuals in the control group. Table 1 presents the breakdown of the examined groups. The cleft patients were further divided into three separate subgroups, comprising individuals with bilateral cleft lip and palate (BCLP), left-sided cleft lip and palate (L-CLP), and right-sided cleft lip and palate (R-CLP). The fourth one consisted of individuals in the control group.  
The researchers formulated several hypotheses for the study:  
* The asymmetry of the incisors would be evident in their quantity measurements.
* The asymmetry of the incisors would be observed in the mesiodistal measurement of tooth width.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **BCLP** & **L-CLP** & **R-CLP** & **Control** \\ \hline Females & 17 (11.1\%) & 36 (23.4\%) & 8 (5.2\%) & 96 (64\%) \\ Males & 19 (12.3\%) & 51 (33.1\%) & 23 (14.9\%) & 55 (36\%) \\ Sum & 36 (23.4\%) & 87 (56.5\%) & 31 (20.1\%) & 151 (100\%) \\ \hline \hline \end{tabular}
\end{table}
Table 1: The structure of the examined groups (BCLP—bilateral cleft lip and palate; L-CLP— unilateral, left-sided cleft lip and palate; and R-CLP—unilateral, right-sided cleft lip and palate).  
* In unilateral clefts, the cleft side would exhibit a higher prevalence of dental anomalies compared to the opposite side.
* In bilateral clefts, dental anomalies would be equally present on both sides.