Correlation between mandibular third molar and mandibular incisor crowding: A retrospective CBCT-based study

Background. Late mandibular incisor crowding is a fairly common phenomenon experienced by growing adults. The etiology of late mandibular incisor crowding, however, is controversial and inconclusive. Hence, this study aimed to investigate the correlation between mandibular third molar and mandibular incisor crowding using Cone-beam computed tomography (CBCT) data. Methods. The study consisted of 40 samples of CBCT images divided into two groups (n=20). Group A comprised CBCT images without third molars, and group B included CBCT images with third molars. The images were observed in the axial view and manually marked to calculate the amount of crowding using Little’s irregularity index. The obtained values were statistically analyzed using Pearson’s correlation test. SPSS 23 was used for statistical analysis. Results. The results showed a positive correlation between the mandibular third molars and mandibular incisor crowding, which was significant (P=0.033). The mean Little’s irregularity index score for groups A and B were 4.26 and 6.799, respectively (P=0.033). Conclusion. The positive correlation between the two groups suggests an association between the mandibular third molars and mandibular incisor crowding.

Corneal ectasia in mothers of Down syndrome children

In this study, corneal findings regarding keratoconus (KC) and early KC among mothers with Down syndrome children (MDS) and a group of age-at-delivery-matched mothers with normal children (MNC) were compared. KC was diagnosed based on the presence of a clinical sign and at least one abnormal tomographic or biomechanical criterion. Early KC was defined as having no clinical sign in the presence of at least one abnormal tomographic or biomechanical criterion. The normal subgroups in each group were compared in terms tomographic and biomechanical parameters. In MDS and MNC, the prevalence rates were 6.5% and 1.6% for KC (P = 0.047), and 30.9% and 14.3% for early KC (P = 0.014), respectively. Comparison between the two normal subgroups showed significant differences in mean index of height asymmetry, irregularity index, anterior asphericity, pentacam random forest index, corneal stiffness parameters at first applanation, deformation amplitude ratios, integrated radius-1 mm, highest concavity deflection amplitude, biomechanical corrected IOP, peak distance, and radius (all P < 0.05). This study showed that MDS are more likely to have KC and also to have thinner, steeper and softer corneas compared to MNC. This results support the need for further work for determining the risk of delivering a child with DS.

An evaluation of the relationship between periocular anthropometric measurements and mandibular incisor crowding

Aim: To determine whether a relationship exists between the periocular anthropometric meas-urements (POAM), intercanine width, and Little’s irregularity index (measures the crowding of mandibular incisors) in the Turkish population. Methodology: Ninety-four children (49 with mandibular crowding and 45 controls) aged between 12-18 years were included in this study. Inter-outer canthal distance (IOCD), in-ter-inner canthal distance (IICD), interpupillary distance (IPD), inter-canine width (ICW), and Littles’irregularity index (LII) of subjects were measured from two standardized digital pho-tographs using a public domain Java processing program (ImageJ software). Spearman correla-tion coefficient and multiple linear regression tests were used to investigate the relationship between POAM, and ICW, and LII. Results: In the mandibular crowding group, the means of IICD, OICD, IPD, and ICW were 30.6 ± 1.7 mm, 82.4 ± 2.0 mm, 59.2 ± 1.6 mm, 23.3 ± 1.1 mm, respectively. In controls, the mean of the measurements was found to be 32.1 ± 1.5 mm, 84.4 ± 2.4 mm, 60.1 ± 1.9 mm, 24.6 ± 1.4 mm, respectively. There were statistically significant differences between groups among all variables (p <0.001). There was a negative correlation between POAM and ICW with LDI. Especially, high correlation was found in ICW and IICD variables (r = -. 732, p <.001 and r = -705, p <.001, respectively). As a result of multivariate regression analysis, IICD and ICW were found to be affected the crowding negatively and significantly (p = .003 and p = .026, respectively). Conclusion: According to the results obtained from our study, it was concluded that IICD which remains stable after the age of 10 years and ICW can be used to predict irregularities in mandibular incisors in children in the Turkish population. How to cite this article: Kızıltan Eliaçık BB. An evaluation of the relationship between periocular anthropometric measurements and mandibular incisor crowding. Int Dent Res 2021;11(Suppl.1):216-221. https://doi.org/10.5577/intdentres.2021.vol11.suppl1.31 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Presence and Maturation Dynamics of Mandibular Third Molars and Their Influence on Late Mandibular Incisor Crowding: A Longitudinal Study

The objective of this study was to investigate the relationship between the absence, presence and dynamics of mandibular third molar development and the occurrence and amount of late mandibular incisor crowding. Dental plaster casts and panoramic radiographs of 72 orthodontically untreated subjects from the Nittedal growth study, Norway were analyzed. The subjects were recalled for a checkup at 12, 15, 18 and 21 years of age. Mandibular incisor crowding was assessed using Little’s irregularity index and dental maturation of the third molars by the Cameriere’s index. The majority of the subjects (64%) had ≥1 mm increase in irregularity; 22% experienced an increase of 0.1–0.9 mm and 14% had unchanged or decreased irregularity. Incisor irregularity increased with age, regardless of absence or presence of third molars. The amount of change in incisor irregularity from 12 to 21 years did not differ significantly between subjects with hypodontia of third molars, extraction and those with third molars present. No differences were observed between erupted, unerupted or impacted third molars. No correlation was found between the amount of change in irregularity and maturation of the third molars. In conclusion, occurrence and amount of mandibular late incisor crowding is not significantly influenced by the presence of mandibular third molars or their development dynamics.

Simultaneous transepithelial topographic-guided laser and cross-linking to correct irregular astigmatism in a pediatric patient

Purpose: To evaluate an original approach for treating corneal ectasia and irregular astigmatism secondary to penetrating trauma in a pediatric patient. Case report: An 11 year old patient had a penetrating trauma in right eye when he was two and the refractive error was +1.50 diopters sphere −6.00 diopters cylinder axis 95°. To correct irregular astigmatism, the patient underwent simultaneous transepithelial topographic-guided laser Central Corneal Remodeling (CCR) and Corneal Cross-linking (CXL) in the attempt to regularize corneal ectasia and to improve the quality of vision. Uncorrected and Corrected Distance Visual Acuity were measured using Efficacy and Safety indexes; objective and subjective qualities of vision were evaluated using respectively corneal morphological irregularity index and National Eye Institute Visual Function questionnaires. Conclusions: Twelve month follow up suggests that simultaneous CCR and CXL could be effective to improve the quality of vision and to halt the progression of post-traumatic ectasia in pediatric patients.

Tooth alignment and pain experience with A-NiTi versus Cu-NiTi: a randomized clinical trial

Background Nickel-titanium (NiTi) archwires are routinely used for initial leveling and alignment of teeth in orthodontic treatment. This study aimed to clinically compare the level of pain and tooth alignment in orthodontic treatment with A-NiTi versus Cu-NiTi archwires. Methods In this parallel randomized clinical trial, 88 orthodontic patients (12–25 years) with an irregularity index > 2 mm in the anterior site of the lower dental arch who required non-extraction orthodontic treatment of the lower arch were randomized into two age- and sex-matched groups (n = 44) for treatment with A-NiTi and Cu-NiTi initial archwires. Each archwire was used for 6 weeks. After 6 weeks, the irregularity index was measured, and the level of pain was scored using the Modified McGill pain questionnaire (MPQ) and visual analog scale (VAS) according to the time of onset and duration of pain, and analgesic intake. Data were analyzed by paired t test, independent samples t test, and Chi-square test (P < 0.05). Results The irregularity index significantly decreased in both groups after 6 weeks of treatment (P < 0.001). However, the difference in this respect was not significant between the two groups (P > 0.05). Pain perception (P = 0.487), duration of pain (P = 0.546), and analgesic intake (P = 0.102) were not significantly different between the two groups either. Conclusion Both A-NiTi and Cu-NiTi archwires are equally effective for tooth alignment in the anterior site of the lower dental arch and have no significant difference with regard to the level of pain experienced by patients. Trial registration number: IRCT20190705044102N1 and Name of the registry: Iranian registry of clinical trials (https://irct.ir/) Date of registration: September, 26, 2019

Comparative assessment of relapse and failure between CAD/CAM stainless steel and standard stainless steel fixed retainers in orthodontic retention patients:

ABSTRACT Objectives To compare relapse and failure rates of computer-aided design/computer-aided manufacturing (CAD/CAM) and standard fixed retainers. Materials and Methods This single-center, single-blinded, prospective randomized clinical trial included 46 patients who completed active orthodontic treatment and complied with retention visits. The patients were randomly assigned to three groups: CAD/CAM group with multistranded stainless steel wires (CAD/CAM, n = 16), Lab group with the same multistranded wires (lab, n = 16), and control group with stainless steel Ortho-FlexTech wires (traditional, n = 14). Intraoral scans were obtained at placement of fixed retainers (T1), 3-month visit (T2), and 6-month visit (T3) and measured for intercanine width and Little's Irregularity Index. Failures were recorded. Results The CAD/CAM group experienced less intercanine width decrease than the traditional group at 3 months (mean difference, 0.83 ± 0.16 mm; 95% confidence interval [CI], 0.44–1.22; P &lt; .001) and 6 months (mean difference, 1.23 ± 0.40 mm; 95% CI, 0.19–2.27; P &lt; .05). The CAD/CAM group experienced less increase in Little's Irregularity Index compared with the lab group within 3 months (mean difference, 0.81 ± 0.27 mm; 95% CI, 0.12–1.49; P &lt; .05). Failures from greatest to least were experienced by the lab group (43.8%), the CAD/CAM group (25%), and the traditional group (14.3%). Conclusions Within 6 months of bonding fixed retainers, CAD/CAM fixed retainers showed less relapse than lab-based and traditional chairside retainers and less failures than lab-based retainers.

Corneal Ectasia in Mothers of Down Syndrome Children

In this study, corneal findings regarding keratoconus (KC) and early KC among mothers with Down syndrome children (MDS) and a group of age-at-delivery-matched mothers with normal children (MNC) were compared. KC was diagnosed based on the presence of a clinical sign and at least one abnormal tomographic or biomechanical criterion. Early KC was defined as having no clinical sign in the presence of at least one abnormal tomographic or biomechanical criterion. The normal subgroups in each group were compared in terms tomographic and biomechanical parameters. In MDS and MNC, the prevalence rates were 6.5% and 1.6% for KC (P = 0.047), and 30.9% and 14.3% for early KC (P = 0.014), respectively. Comparison between the two normal subgroups showed significant differences in mean index of height asymmetry, irregularity index, anterior asphericity, pentacam random forest index, corneal stiffness parameters at first applanation, deformation amplitude ratios, integrated radius-1mm, highest concavity deflection amplitude, biomechanical corrected IOP, peak distance, and radius (all P < 0.05). This study showed that MDS are more likely to have KC and also to have thinner, steeper and softer corneas compared to MNC. This results support the need for further work for determining the risk of delivering a child with DS.

Correlation of Lower Third Molar Angulation and Posterior Space Discrepancy with Mandibular Anterior Crowding using 3d Intra Oral Scanner

OBJECTIVES: To objectively determine the correlation of lower third molar angulation and posterior space discrepancy with mandibular anterior crowding digitally using intraoral scanner. METHODOLOGY: Cross sectional analytical study conducted at Rehman College of Dentistry (RCD) Peshawar from15th November 2020 till 15th December 2020. Lower third molar angulation and posterior space discrepancy were measured by IC 3.1 measure software, using digital Orthopantomograms (OPG). Digitally scanned models by (CS 3600 intraoral scanner) were analyzed using (CS 3600 3D software). Sample was divided into Control (N=30; perfect alignment), Experimental (N=30; crowding >1mm) groups, based on Little’s Irregularity Index. Both lower third molar angulation and posterior space discrepancy (Ganss Ratio) were correlated with lower anterior crowding using Pearson’s Correlation. To determine any difference between two groups independent t-test was used. RESULTS: Statistically insignificant difference and a weak correlation were found for Ganss ratio and third molar angulation in both control and experimental groups. CONCLUSION: Third molar angulation and the retro molar space has no direct effect on the lower anterior crowding.

Transfer Accuracy of Two 3D Printed Trays for Indirect Bracket Bonding—An In Vitro Pilot Study

The present study aimed to investigate the impact of hardness from 3D printed transfer trays and dental crowding on bracket bonding accuracy. Lower models (no crowding group: Little’s Irregularity Index (LII) < 3, crowding group: LII > 7, n = 10 per group) were selected at random, digitized, 3D printed, and utilized for semiautomated virtual positioning of brackets and tubes. Hard and soft transfer trays were fabricated with polyjet printing and digital light processing, respectively. Brackets and tubes were transferred to the 3D printed models and altogether digitized using intraoral scanning (IOS) and microcomputed tomography (micro-CT) for assessment of linear and angular deviations. Mean intra- and interrater reliability amounted to 0.67 ± 0.34/0.79 ± 0.16 for IOS, and 0.92 ± 0.05/0.92 ± 0.5 for the micro-CT measurements. Minor linear discrepancies were observed (median: 0.11 mm, Q1–Q3: −0.06–0.28 mm). Deviations in torque (median: 2.49°, Q1–Q3: 1.27–4.03°) were greater than angular ones (median: 1.81°, Q1–Q3: 1.05°–2.90°), higher for hard (median: 2.49°, Q1–Q3: 1.32–3.91°) compared to soft (median: 1.77°, Q1–Q3: 0.94–3.01°) trays (p < 0.001), and torque errors were more pronounced at crowded front teeth (p < 0.05). In conclusion, the clinician should carefully consider the potential impact of hardness and crowding on bracket transfer accuracy, specifically in torque and angular orientation.