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, Xi Wen , Jing Geng , Yan Gu Abstract : Objective: This study aimed to determine the maxillary and mandibular basal bone regions and explore the three-dimensional positional relationship between the dentition and basal bone regions in patients with skeletal Class I and Class II malocclusions with mandibular retrusion. Methods: Eighty patients (40 each with Class I and Class II malocclusion) were enrolled. Maxillary and mandibular basal bone regions were determined using cone-beam computed tomography images. To measure the relationship between the dentition and basal bone region, the root position and root inclination were calculated using the coordinates of specific fixed points by a computer program written in Python. Results: In the Class II group, the mandibular anterior teeth inclined more labially (P < 0.05), with their apices positioned closer to the external boundary. The apex of the maxillary anterior root was positioned closer to the external boundary in both groups. Considering the molar region, the maxillary first molars tended to be more lingually inclined in females (P = 0.037), whereas the mandibular first molars were significantly more labially inclined in the Class II group (P < 0.05). Conclusions: Mandibular anterior teeth in Class II malocclusion exhibit a compensatory labial inclination trend with the crown and apex relative to the basal bone region when mandibular retrusion occurs. Moreover, as the root apices of the maxillary anterior teeth are much closer to the labial side in Class I and Class II malocclusion, the range of movement at the root apex should be limited to avoid extensive labial movement.
, Gul Yildiz Telatar, Faruk SaydamAbstract : Objective: To determine whether the gonial angle on digital panoramic radiographs is associated with vitamin D receptor (VDR) Taql polymorphism. Methods: Genomic DNA samples were collected from the buccal mucosa of patients aged 26–43 years. TaqMan assay for single nucleotide polymorphism genotyping was used to detect the genotype of Taql polymorphism. The gonial angle was measured bilaterally on panoramic radiography. The normal gonial angle was fixed as 121.8°, and it represented the cutoff value for the high gonial angle (HGA) and low gonial angle (LGA) groups. Various genetic models were analyzed, namely dominant (homozygous [AA] vs. heterozygous [AG] + polymorphic [GG]), recessive (AA + AG vs. GG), and additive (AA + GG vs. AG), using the chi-squared test. Results: The reliability of the gonial angle measurement was analyzed using a random sample (26%) of the tests, with the intra-examiner correlation showing an intra-class correlation coefficient of 0.99. The frequencies of the AA, AG, and GG genotypes of rs731236 polymorphism were 40.5%, 41.9%, and 17.6% in the HGA group and 21.8%, 51.0%, and 27.2% in the LGA group, respectively (P = 0.042). A statistically significant difference was observed in the allele frequencies between the two groups (P = 0.011). Moreover, a significant correlation was observed in the dominant genetic model. Conclusions: Taql polymorphism in the VDR gene plays a critical role in the vertical growth of the mandible and decreased gonial angle.
, Qiao Chang , Shuran Liang , Yuxing Bai Abstract : Objective: A three-dimensional-printed individual titanium plate was applied for maxillary protraction to eliminate side effects and obtain the maximum skeletal effect. This study aimed to explore the stress distribution characteristics of sutures during maxillary protraction using individual titanium plates in various directions and locations. Methods: A protraction force of 500 g per side was applied at forward and downward angles between 0° and 60° with respect to the Frankfort horizontal plane, after which the titanium plate was moved 2 and 4 mm upward and downward, respectively. Changes in sutures with multiple protraction directions and various miniplate heights were quantified to analyze their impact on the maxillofacial bone. Results: Protraction angle of 0–30° with respect to the Frankfort horizontal plane exhibited a tendency for counterclockwise rotation in the maxilla. At a 40° protraction angle, translational motion was observed in the maxilla, whereas protraction angles of 50–60° tended to induce clockwise rotation in the maxilla. Enhanced protraction efficiency at the lower edge of the pyriform aperture was associated with increased height of individual titanium plates. Conclusions: Various protraction directions are suitable for patients with different types of vertical bone surfaces. Furthermore, when the titanium plate was positioned lower, the protraction force exhibited an increase.
, Anna Alessandri-Bonetti , Geraldine Gemelli , Linda Sangalli , Patrizia Gallenzi Abstract : Objective: The study aimed to assess the prevalence of dental malocclusion, orthodontic parameters, and parafunctional habits in children with developmental dyslexia (DD). Methods: Forty pediatric patients (67.5% boys and 32.5% girls, mean age: 11.02 ± 2.53 years, range: 6–15 years) with DD were compared with 40 age- and sex-matched healthy participants for prevalence of dental malocclusion, orthodontic parameters, and parafunctional habits. Dental examinations were performed by an orthodontist. Results: Pediatric patients with DD exhibited a significantly higher prevalence of Angle Class III malocclusion (22.5% vs. 5.0%, P = 0.024), deep bite (27.5% vs. 7.5%, P = 0.019), midline deviation (55.0% vs. 7.5%, P < 0.0001), midline diastemas (32.5% vs. 7.5%, P = 0.010), wear facets (92.5% vs. 15.0%, P < 0.0001), self-reported nocturnal teeth grinding (82.5% vs. 7.5%, P < 0.0001), nail biting (35.0% vs. 0.0%, P < 0.0001), and atypical swallowing (85.0% vs. 17.5%, P < 0.0001) compared to that in healthy controls. Conclusions: Pediatric patients with DD showed a higher prevalence of Class III malocclusion, greater orthodontic vertical and transverse discrepancies, and incidence of parafunctional activities. Clinicians and dentists should be aware of the vulnerability of children with dyslexia for exhibiting malocclusion and encourage early assessment and multidisciplinary intervention.
, Fatemeh Safari , Allahyar Geramy , Tabassom Hooshmand , Mohammad Javad Kharazifard , Sepideh Arab Abstract : Objective: This study aimed to assess the effects of commonly consumed hot drinks on the force decay of orthodontic elastomeric chains. Methods: This in vitro experimental study evaluated 375 pieces of elastomeric chains with six rings placed on a jig. Four rings were stretched by 23.5 mm corresponding to the approximate distance between the canine and the second premolar. Fifteen pieces served as reference samples at time zero, and 360 pieces were randomized into four groups: control, hot water, hot tea, and hot coffee. Each group was further divided into six subgroups (n = 15) according to the different exposure periods. The specimens in the experimental groups were exposed to the respective solutions at 65.5°C four times per day for 90 seconds at 5-second intervals. The control group was exposed to artificial saliva at 37°C. The force decay of the samples was measured at 1, 2, 7, 14, 21, and 28 days using a universal testing machine. Data were analyzed using repeated-measures analysis of variance. Results: Maximum force decay occurred on day 1 in all groups. The minimum force was recorded in the control group, followed by the tea, coffee, and hot water groups on day 1. At the other time points, the minimum force was observed in the tea group, followed by the control, coffee, and hot water groups. Conclusions: Patients can consume hot drinks without concern about any adverse effect on force decay of the orthodontic elastomeric chains.
, Nilüfer Ersan , Yunus Ziya Arslan , Erol Cansız Abstract : Objective: This retrospective study evaluated the mandibular condyle position before and after bimaxillary orthognathic surgery performed with the mandibular condyle positioned manually in patients with mandibular prognathism using cone-beam computed tomography. Methods: Overall, 88 mandibular condyles from 44 adult patients (20 female and 24 male) diagnosed with mandibular prognathism due to skeletal Class III malocclusion who underwent bilateral sagittal split ramus osteotomy (BSSRO) and Le Fort I performed using the manual condyle positioning method were included. Cone-beam computed tomography images obtained 1–2 weeks before (T0) and approximately 6 months after (T1) surgery were analyzed in three planes using 3D Slicer software. Statistical significance was set at P < 0.05 level. Results: Significant inward rotation of the left mandibular condyle and significant outward rotation of the right mandibular condyle were observed in the axial and coronal planes (P < 0.05). The positions of the right and left condyles in the sagittal plane and the distance between the most medial points of the condyles in the coronal plane did not differ significantly (P > 0.05). Conclusions: While the change in the sagittal plane can be maintained as before surgery with manual positioning during the BSSRO procedure, significant inward and outward rotation was observed in the axial and coronal planes, respectively, even in the absence of concomitant temporomandibular joint disorder before or after the operation. Further long-term studies are needed to correlate these findings with possible clinical consequences.
, Jung-Jin Park , Seong-Hun Kim Abstract : Objective: Lingual fixed retainers, made from 0.0175-inch 3-strand twisted stainless steel wire (TW) and 0.016 × 0.022-inch straight rectangular wire (RW), are generally used in clinical practice. This study aimed to calculate their accuracy by comparing the discrepancy between computer-aided customized retainers made from these two types of wires. Methods: Eleven orthodontic patients were selected, resulting in 22 maxillary and mandibular three-dimensional printing dental models. Two types of lingual fixed retainers were bonded from canine to canine. To determine the accuracy, five points were chosen for each model, resulting in 110 selected points. The absolute values of the distances on the x-, y-, and z-axes were measured to compare the accuracy of the two types of computer-aided retainers. Results: The accuracy of the two types of retainers did not differ significantly in the x- and z-axes, but only in the y-axis (P < 0.01), where RW-fixed retainers exhibited a slightly but significantly increased distance compared to the TW. Conclusions: Both types of retainers showed high accuracy; however, RW had a slight but statistically significant difference along the y-axis compared with TW. This type of computer-aided design/computer-aided manufacturing bending machine is limited to two dimensions, and the dental arch is curved. Therefore, RW may require slight manual adjustment by the practitioner after manufacturing.
, Rolf G. Behrents, Steven J. Lindauer , David P. Rice 
2.6
2023 IF
