BACKGROUND: This study aims to verify Bolton\'s values for tooth size ratios and to evaluate possible relationships to different occlusal traits using precise digital measurement methods.
METHODS: Including 1000 consecutively selected patients from three study centres a digital, partially automated model analysis was performed utilizing the software OnyxCeph. The measurements comprised tooth width for calculation of anterior (AR) and overall ratio (OR) as a percentage, arch width, length, perimeter, overjet, overbite, space analysis in millimetre and the assessment of the angle classification.
RESULTS: AR and OR were significantly increased compared to Bolton\'s ratios of 77.2% (AR) and 91.3% (OR). In the gender comparison, male patients showed larger tooth size ratios, especially in the OR. Patients with Angle Class II/1 and II/2 had smaller tooth size ratios than patients with Angle Class III and I. Thus, patients with Angle Class II/1 had the largest tooth diameters in all maxillary teeth and with Angle Class II/2 the smallest tooth sizes in the mandible. The largest tooth widths in the lower jaw were observed in the Angle Class III patient group. Furthermore, a negative correlation from AR/OR to overjet, overbite, and available space in lower jaw as well as a positive correlation to available space in upper jaw was detected.
CONCLUSIONS: There is a clear correlation between the tooth size ratios and the present dysgnathia as well as other orthodontically relevant occlusal traits. This prior knowledge about our patients is extremely important to create an individualized treatment plan and enable sufficient occlusion. To achieve a functionally good occlusion with correct overjet and overbite, it is essential that the maxillary and mandibular teeth are proportional in size. Any deviation from the ideal patient in terms of tooth size, number, shape, or arch must be considered in the pre-therapeutic treatment plan in combination with the existing dysgnathia in order to be able to achieve a stable anterior and posterior occlusion with appropriate adjustments to the therapy post-therapeutically.

Information about the use of stone tools in the past is encoded in the wear patterns left on their surface; however, post-depositional processes can modify and obstruct these traces. One aim in the field of lithic functional analysis is to develop methods to detect and quantify these traces on stone tools. The occlusal fingerprint analysis (OFA) is a well-established method in dental wear studies to virtually simulate dental occlusal (contact between teeth) stroke movements and thus locate and quantify the sequential contact between opposing tooth crowns. Reaching across disciplines, we conducted controlled experiments to test the applicability of the OFA method on stone tools to address the challenge of use-wear quantification and localisation, and therefore the identification of post-depositional wear. Our findings reveal a clear overlap between zones of experimentally produced use-wear and OFA-calculated contact areas. We demonstrate OFA as a potential method to generate models of multiscale use-wear that can be used as references on experimental tools to identify post-depositional surface modifications on stone tool artefacts.

OBJECTIVE: To determine the prevalence of malocclusion in Portuguese preschool children, to characterise occlusion in the deciduous dentition, and to study the relationship between malocclusion, sex, and age.
METHODS: This cross-sectional study included 3-6 years old children, from 25 randomly selected kindergartens from the Lisbon district. Data were collected through an oral examination. Malocclusion was defined as the presence of any type of occlusion anomaly (anterior crossbite, edge-to-edge, increased overjet, open bite, deep overbite, posterior crossbite, scissor bite), spacing anomaly (crowding), or dentition anomaly (supernumerary teeth, agenesis, malformations). Canine class, terminal plane of the deciduous second molars and type of Baume arch were also recorded. Statistical analysis included descriptive and chi-squared test (α = 0.05).
RESULTS: The sample included 426 children with a global prevalence of malocclusion of 60.6%. Occlusion anomalies were the most prevalent (59.2%), the most frequent being deep overbite (27%), increased overjet (22.1%) and posterior crossbite (14.1%). Crowding had a prevalence of 1.6% and agenesis of 1.4%. Class I canine (57.3%), straight second molar terminal plane (60.1%) and type I Baume arch (53.3%) were the most common. The mean overjet was 2.6 mm (sd = 2.1) and the mean overbite was 2.2 mm (sd = 2.1). Age was associated with the presence of occlusion anomalies (p = 0.03), and increased overjet prevalence was found to be higher in girls (p = 0.03).
CONCLUSIONS: The prevalence of malocclusion was high, with occlusion anomalies being the most prevalent. It is important to identify modifiable risk factors associated with malocclusion to prevent this condition in both the deciduous and permanent dentitions.

Background/Objectives: Temporomandibular disorders (TMD) encompass a range of musculoskeletal and neuromuscular conditions affecting the temporomandibular joint (TMJ) and associated structures. This cross-sectional study, conducted in a Portuguese TMD department, aimed to assess the relationship between malocclusion and TMD severity. Methods: Data on demographic variables, TMD clinical symptoms, and malocclusion classes were collected using the EUROTMJ database. The Chi-square test (χ2) identified associations, with their intensity measured by Cramér\'s V (φc). Results: The study included 1170 patients (932 females and 238 males), with a mean age of 41.73 ± 16.80 years. Most patients exhibited Angle Class I malocclusion (85.5%), followed by Angle Class II (13.5%) and Angle Class III (1.1%). Class II malocclusion was associated with increased TMD severity (p < 0.001), higher myalgia levels (p = 0.002), more frequent disc displacement without reduction (p = 0.002) and lower maximum mouth opening values (Class II: 38.13 ± 7.78 mm, Class I: 39.93 ± 8.67 mm). Significant associations were also found between malocclusion type and arthralgia (p = 0.021), mouth-opening limitation (p = 0.016), and TMJ crepitus (p = 0.017). In cases of malocclusion, the presence of oral signs of bruxism explained the degree of myalgia, disc displacement, and severity (p = 0.003; p = 0.048; p = 0.045). Conclusions: This study highlights that (1) the most common type of dental malocclusion in TMD patients was Class I; (2) Class II malocclusion was associated with increased TMD severity and oral signs of bruxism; and (3) Class III was rarely observed in TMD consultation. The findings suggest that bruxism behavior in cases of malocclusion may be significant in TMD.

BACKGROUND: This study investigated the characteristics of Monson\'s sphere in Chinese young adult females with individual normal occlusion to provide a reference for oral rehabilitation in prosthodontic and orthodontic treatments.
METHODS: Points at the dental cusps and incisal edges were selected from 51 digital mandibular dental models of Chinese young adult females (aged 18-22 years) with individual normal occlusion. Monson\'s spheres were fitted to the selected points based on the least-squares principle and the radii were calculated. The deviation of each selected point from its relative spherical surface was also calculated. The radii and deviations of these points were examined using conventional descriptive statistics and distributions of the most deviated points inside and outside the spheres were analyzed.
RESULTS: The mean radius of Monson\'s sphere in Chinese young adult females was 79.60 ± 14.13 mm. The deviation of each selected point from its relative sphere surface was 0.38 ± 0.30 mm. The maximum deviations inside and outside the sphere were 0.93 ± 0.25 mm and 0.95 ± 0.30 mm, respectively. The most deviated points outside the spheres were mainly distributed at the distolingual cusps of the mandibular second permanent molars (31.37%), while those inside the spheres were mainly distributed at the mesiolingual cusps of the mandibular first permanent molars (45.10%).
CONCLUSIONS: The radius of Monson\'s sphere in Chinese young adult females was smaller than the classic four-inch value suggested by Monson. Deviation was observed from all selected points to their Monson\'s sphere surface, with the most deviated points distributed primarily in the molar region.

OBJECTIVE: To investigate the correlation between the occlusal canting and the bilateral temporomandibular joint (TMJ) space in adult and juvenile mandibular deviation patients and study the mutual influence between the occlusal canting and mandibular position, in order to provide references for clinical treatment.
METHODS: CBCT data of mandibular deviation patients（20 adults，20 juveniles）were selected. Inivo5 Dental Anatomage software was used to reconstruct the structures. The occlusal cant and vertical height of the bilateral maxillary from canines to first molars were measured, and the vertical heights difference between the same teeth on both sides was calculated. The anterior, superior and posterior space of temporomandibular joint were measured respectively in both groups. Pearson correlation analysis between the occlusal canting and bilateral condylar space was carried out by using SPSS 17.0 software package.
RESULTS: In the juvenile group, negative correlations were found between the occlusal cant and the superior TMJ space on the deviated side (P＜0.05). Negative correlation was found between the vertical height difference of bilateral canines and the anterior TMJ space on the deviated side in the juvenile group(P＜0.05). In the adult group, no significant correlation was observed among those correlated examination (P＞0.05).
CONCLUSIONS: The occlusal canting is moderately correlated with mandibular position in the early stage of mandibular deviation patients. Early treatment of mandibular deviation is of great importance in preventing its progression into severe skeletal malocclusion, and more attention should be paid on the correction of the canted frontal occlusion plane.

BACKGROUND: Bilateral posterior crossbite (BPXB) is a severe malocclusion associated with maxillary hypoplasia. BPXB may involve the same or a different number of teeth between the sides.
OBJECTIVE: To evaluate the masticatory function in BPXB and the association between the masticatory alterations and the occlusal features of BPXB.
METHODS: This observational study included 170 participants: 130 patients with BPXB (65 occlusally symmetric BPXB, i.e. same number and type of posterior teeth in crossbite between the sides, F = 33, M = 32, median age 9.6 (8.2-13) [years.months]; 65 patients occlusally asymmetric BPXB, F = 30, M = 35, median age 9.9 (8.3-13.6)) and 40 controls (F = 25, M = 15, median age 10.2 (9.4-11.6)). The masticatory function was evaluated by the detection of the Reverse Chewing Cycles (RCCs) recorded with a kinesiograph using standardised soft and hard boluses.
RESULTS: The frequency of RCCs was significantly increased in all BPXB patients compared to controls (p < .000). In symmetric BPXB patients, there were no significant differences in the frequency of RCCs during chewing on the left or the right side. In asymmetric BPXB patients, the frequency of RCCs was significantly increased during chewing on the side with relatively more teeth in crossbite (p < .000).
CONCLUSIONS: The masticatory function was significantly altered in all BPXB patients and it was differently affected by symmetric or asymmetric occlusal features of the malocclusion.

This study aimed to assess the changes in interproximal contacts before and after orthodontic treatment using the OXIS classification. OXIS refers to the types of contacts that is open (O), point contact (X), straight contact (I), and curved contact (S), and thus the acronym \"OXIS\". Interproximal contact data of 30 orthodontic patients were obtained at three time points: T0, at the beginning of treatment; T1, at the end of fixed appliance treatment; and T2, one-year post-treatment. For the maxillary second molar-first molar contact, the most common contact at T0, was the \"S\" pattern (41.6%) which increased to 61.6% at T1 and reduced to 48.3% at T2. For the maxillary first molar-second premolar contact, maxillary second premolar-first premolar contact, and maxillary first premolar-canine contact, the most common contact at T0 was the \"I\" pattern (58.3%, 46.5% and 43.3%, respectively), which increased to 88.3%, 93.3% and 73.3%, respectively at T1 and decreased to 80%, 88.3% and 71.6%, respectively at T2. For the maxillary canine-lateral incisor contact and lateral-central incisor contact, the most common contact at T0 was the \"O\" pattern (45% and 33.3%) while it was the \"X\" pattern at T1 (63.3% and 80%) and T2 (58.3% and 80%). A similar observation was made for the posterior mandibular and anterior teeth. There was statistical significance for most of the changes in the mandibular contacts (p ˂ 0.05). Interproximal contacts change significantly from T0 to T1. Broader contacts were normal at T1 and T2 in the posterior segments. At T2, changes in the interproximal contacts were observed in the posterior segments, and substantial evidence was available, particularly for the mandibular arch.

This study aimed to assess the impact of occlusal loading on secondary tooth eruption and to determine the extent to which altering the occlusal loading influences the magnitude of secondary eruption through an experimental rat model. The present sample consisted of 48 male Wistar rats. At the onset of the experiment, 24 rats were 4 weeks old (young rats) and 24 rats were 26 weeks old (adult). Within each age group, the rats were further divided into two equal subgroups (12 rats each), receiving either a soft- or hard-food diet for the 3-month duration of the experiment. The primary outcome was the tooth position changes relative to stable references in the coronal plane by evaluating the distance between the mandibular first molars and the inferior alveolar canal. Microcomputed tomography scans were taken from all rats at three standardized intervals over the 3-month study period. Descriptive statistics were calculated by age and diet over time, and the evolution of the outcomes were plotted by age and diet over time. Longitudinal data analysis via generalized estimating equations was performed to examine the effect of age, diet and time on the primary outcomes. Secondary tooth eruption was observed in all age groups (young and adult) regardless of diet consistency (soft or hard food). In young rats, the secondary eruption was greater in the animals fed a soft diet than those fed a hard diet. In adult rats, minimal difference in secondary tooth eruption were found between different diet consistencies. Occlusal loading influences secondary tooth eruption in teeth with an established occlusal contact. The quantity of eruption in growing rats is higher when occlusal loading is less, providing a certain amount of secondary tooth eruption occurs. This difference, however, is not evident in adult rats, at least during the given 3-month time frame.

OBJECTIVE: The correlations between the incisal guidance angle (IGA) and occlusal plane angles and temporomandibular joint (TMJ) morphology were investigated in adults with skeletal Class II division II malocclusion.
METHODS: CBCT images of 37 patients were analyzed. It included 19 cases of skeletal Class II division II malocclusion with low angle (study group) and 18 cases of skeletal Class I average angle (control group). The Invivo Dental 5 software was employed to acquire the data of the incisal guidance angle (IGA), occlusal plane angle (FH-OP), anterior occlusal plane angle (FH-AOP) and the TMJ measurement items.
RESULTS: The results of IGA, FH-AOP angle and FH-OP angle showed the study group > the control group (P < 0.05). There were statistically difference in the condylar mediolateral diameters, articular eminence inclination and height, and posterior joint spaces between two groups. No differences were revealed in the condylar anteroposterior diameters, the condylar inclination angle, condylar head width and height, condylar length, glenoid fossa depth and width between two groups. In the study group, IGA showed a moderate correlation with FH-AOP, a weak correlation with FH-OP and condylar mediolateral diameters. Meanwhile, there was a correlation between FH-AOP, FH-OP, and TMJ indicators.
CONCLUSIONS: The IGA was not only related to FH-AOP and FH-OP, but also to the condylar mediolateral diameters. In addition, there was a correlation between the occlusal plane angles and TMJ morphology in skeletal Class II division II low angle malocclusion.
CONCLUSIONS: For patients with skeletal Class II division II low angle malocclusion, adjusting the IGA and the occlusal plane angles could improve the esthetic appearance of the anterior teeth, occlusal function, and TMJ morphology.