This case report describes the successful orthodontic management of a 25-year-old female patient presenting with Class II Division 2 malocclusion, moderate maxillary anterior crowding, and a missing mandibular left first molar. Treatment plan involved extraction of two maxillary first premolars to address crowding and protraction of two mandibular left molars, combined with the strategic use of mini-implants for precise tooth movement control. Ridge-split surgery was adopted to manage alveolar ridge resorption in the edentulous area. This procedure was essential for widening the narrow alveolar ridge, thereby reducing resistance and facilitating the mesial movement of two mandibular left molars. Lingual and labial biomechanics, including linguoincisal elastics and a cantilever system, were utilized to optimize torque control and molar protraction. Clear aligners were employed throughout the treatment phases, navigating challenges such as the closure of extraction spaces and achieving stable buccal interdigitation. The treatment spanned 4 years, using a total of 175 aligners. The initial phase required 66 aligners to close maxillary extraction spaces and the mandibular edentulous space, followed by 52 aligners in the first refinement and 57 aligners in the second refinement phase. Posttreatment evaluations demonstrated successful alignment of dental arches, correction of malocclusion, and enhancement of facial aesthetics. This case highlights the efficacy of integrated orthodontic techniques in achieving comprehensive functional and aesthetic outcomes in complex orthodontic cases.

This study aimed to analyse the 2010-2018 cohort data of the National Health Insurance Service to examine the association between applying sealants in the first molars of children and their early dental impairment.

Based on the two-level mixed effect model (individual four teeth), the study participants were divided into two groups: those with sealants on all four first molars and those without sealants to determine the association between sealants and early impairment. We analysed teeth that had undergone extraction or canal filling to determine early impairment.

The rate of early impairment in the first molars was approximately 7.4 times lower in the sealant group (0.65%) than in the non-sealant group (4.83%). Early impairment of first molars was higher in females, medically cared for and in rural populations. It was also higher in the maxillary first molars (3.7%) than in the mandibular first molars (3.49%), in more rural areas, and in lower household income groups. In generalised linear mixed models, first molars with sealants were 14.9% less likely to have early impairment than those without sealants (p = 0.000).

The study findings suggest that applying sealants on the first molars is important to prevent early dental caries development and prolong the functional integrity of first molars. In addition, we found that maxillary first molars were more susceptible to early impairment than mandibular first molars, even when sealant was applied.

Extraction of the permanent first molars is sometimes necessitated in children and adolescents due to deep carious lesions or developmental defects.

To estimate the prevalence of spontaneous space closure after extraction of permanent first molars and identify factors associated with it.

Unrestricted searches in five databases for human studies until February 2024.

Longitudinal before-and-after (cohort) human studies assessing eruption of the permanent second molars and spontaneous space closure after extraction of the permanent first molar.

Study selection, data extraction, and risk of bias assessment were performed in duplicate. Random-effects meta-analyses of average spontaneous space closure prevalences and odds ratios (OR) with their 95% confidence intervals (CI) were performed, followed by meta-regression/sensitivity/reporting biases' analyses and evaluation of our confidence in effect estimates.

Sixteen reports pertaining to 15 studies (1 prospective /14 retrospective) were included covering 1159 patients (ages 5.5-15.0 years [mean 10.0 years]; 45% male on average) and 2310 permanent second molars. The prevalence of spontaneous space closure was higher in the maxilla (nine studies; 85.3%; 95% CI = 73.7%-92.3%) than the mandible (11 studies; 48.1%; 95% CI = 34.5%-62.0%) to a significant extent (nine studies; OR = 7.77; 95% CI = 4.99-12.11; P < 0.001). For both maxillary/mandibular second molars, Demirjian category E was associated with increased space closure odds than earlier/later stages (P < 0.05). Spontaneous space closure in the mandible was seen more often for patients ages 8-10 years (compared with older patients; three studies; OR = 3.32; 95% CI = 1.73-6.36; P < 0.001) and when the mandibular permanent third molar was present (four studies; OR = 2.28; 95% CI = 1.67-3.09; P = 0.003). Additional analyses failed to find any significant modifying factors.

The quality of evidence was very low in all instances due to the inclusion of retrospective studies with methodological issues.

Existing evidence indicates that spontaneous space closure in children and adolescents after extraction of the permanent first molar is seen more often in the maxilla than the mandible. Extraction of the permanent first molar at the Demirjian stage E of the second molar and presence of the lower permanent third molar is associated with increased odds of space closure, but uncertainty persists, due to methodological issues of existing studies.

PROSPERO (CRD42023395371).

Loss of the mandibular first molar is common in orthodontic patients. One treatment option is the mesialization of the second and third molars. This study aimed to investigate the displacement and type of movement in the second molar during mandibular second molar mesialization with clear aligner treatment using finite element analysis in configurations with or without pontic, semipontic, and anatomic pontic for the edentulous space.

Mesialization of the mandibular second molar with clear aligner treatment was simulated using the AlGOR Fempro program (ALGOR, Inc, Pa) with 3 different configurations.

In the transverse direction, the highest rotation occurred in the anatomic pontic model, whereas the lowest rotation was in the semipontic model. In the sagittal axis, although tooth movement was realized by tipping in all scenarios, the semipontic model showed the closest movement to translation because of a higher rate of crown-root movement. In the vertical axis, although extrusion occurred in all configurations, the semipontic model showed the least extrusion forces, whereas the anatomic pontic model showed the most.

Mesiobuccal rotation, mesial tipping, and extrusion were observed in all models. However, the semipontic design had the closest movement to translational. Further randomized, controlled clinical trials are needed to evaluate the effects of different pontic designs on tooth movements.

The biomechanics generated by the clear aligner (CA) material changes continuously during orthodontic tooth movement, but this factor remains unknown during the computer-aid design process and the predictability of molars movement is not as expected. Therefore, the purpose of this study was to propose an iterative finite element method to simulate the long-term biomechanical effects of mandibular molar mesialization (MM) in CA therapy under dual-mechanical systems.

Three groups including CA alone, CA with a button, and CA with a modified lever arm (MLA) were created. Material properties of CA were obtained by in vitro mechanical experiments. MM was conducted by the rebound force exerted by CA material and the mesial elastic force (2N, 30° to the occlusal plane) applied to the auxiliary devices. Stress intensity and distribution on periodontal ligament (PDL), attachment, button and MLA, and displacement of the second molar (M2) during the iterations were recorded.

There was a significant difference between the initial and cumulative long-term displacement. Specifically, compared to the beginning, the maximum stress of PDL decreased by 90% on average in the intermediate and final steps. The aligner was the main mechanical system at first, and then, the additional system exerted by the button and MLA dominated gradually. The stress of attachments and auxiliary devices is mainly concentrated on their interfaces with the tooth. Additionally, MLA provided a distal tipping and extrusive moment, which was the only group that manifested a total mesial displacement of the root.

The innovatively designed MLA was more effective in reducing undesigned mesial tipping and rotation of M2 than the traditional button and CA alone, which provided a therapeutic method for MM. The proposed iterative method simulated tooth movement by considering the mechanical characteristic of CA and its long-term mechanical force changes, which will facilitate better movement prediction and minimize the failure rate.

Introduction The first permanent molars (FPMs) are the first permanent teeth to emerge in the oral cavity, which have an important role in dentition, dental development, and occlusion. FPMs are the most susceptible teeth to caries due to early eruption. There are many adverse consequences related to losing FPMs. Many of the previous studies focused on younger age groups. To the best of our knowledge, there needs to be more newly updated data reported in the literature regarding the status of FPMs in adults in Saudi Arabia. The study aimed to assess the status of permanent first molars among adults in a sample of patients in Riyadh. Methods A cross-sectional retrospective study was conducted from the records of patients in the Dental University Hospital, College of Dentistry, King Saud University (KSU), after obtaining ethical approval. Panoramic images of 810 patients ages 18 and above who were seen at KSU, College of Dentistry, were examined to assess the status of FPMs. A panoramic examination was undertaken for various dental reasons in the time between the years 2017 and 2022. Patients were divided into three age groups: 18-30, 31-50, and >50 years. Data were collected in a particular form and analyzed. The prevalence of missing teeth, as well as restored and carious teeth, were recorded. In addition, further information regarding the type of restoration was recorded. Correlations of the findings regarding age, gender, side, and jaw were determined for all cases and were performed using the chi-square test. P-values less than 0.05 were considered statistically significant. Results A total of 810 patients' panoramic radiographs were studied. Panoramic male study subjects were 382 (47.2%), and females were 427 (52.8%). Three-hundred thirty-nine (339; 41.9%) of them were of less than 30 years of age, 327 (40.4%) were in the age group of 31-50 years, and the remaining 144 (17.8%) were above 50 years of age. The prevalence of missing first molar teeth was 145 (17.9%) for teeth 16, 147 (18.1%) for teeth 26, 207 (25.5%) for teeth 36, and 188 (23.2%) for teeth 46. No statistically significant association was found between the age groups and gender and the first molar missing teeth (p=0.848 & p=0.159). Nineteen point thirteen percent (19.13%) of patients had only one missing FPM, 12.3% of patients had two, and 6.29% of them had three missing FPM teeth. Five point fifty-five percent (5.55%) of patients had four missing FPMs. A total of 56.8% (242) radiographs in the overall sample did not show any missing teeth. The mandibular FPMs (35.2%) were found missing more frequently than their maxillary counterparts (14.8%), and the left mandibular quadrant showed a slightly higher rate of missing FPM (25.55%). Statistically, a significant association was seen between the number of missing FPM among different age groups, p-value <0.0001. The most restored, carious, and replaced tooth was the mandibular left molar, and tooth-color restoration was the most commonly used restoration. Conclusion A high prevalence rate of missing first permanent molars (FPMs) was found in this study population. This calls for more awareness and preventive measures to preserve such significant teeth, therefore reducing the need for complex procedures. Further prospective studies on a larger population are needed to comprehensively evaluate the status of FPMs.

The first molar has been reported to be the most caries prone tooth in the permanent dentition. Orthodontists are treating more adult patients who are more likely to have missing and severely decayed first molars. This article will show the various orthodontic and restorative options for first molars that are already extracted or have to be extracted. The following clinical situations will be addressed: molar uprighting and its advantages for the future restoration vs orthodontic space closure, strategic extraction of salvable first molars, impacted molars, and early extraction of compromised permanent first molars in young children.

Class II division 1 malocclusions are common, and first permanent molars are frequently compromised teeth. Removal of compromised maxillary first permanent molars with planned orthodontic treatment can result in favorable treatment outcomes.

The extraction of permanent molar teeth was first introduced in 1976 as a substitution for premolar extraction in cases with mild crowding. Since then, a number of studies have investigated the effect of permanent molar extraction on dentofacial harmony. Undertaking the procedure of molar extraction is most commonly recommended in response to factors such as: gross caries, large restorations and root-filled teeth, along with its application in the management of anterior open bite and reduction in crowding in facial regions. It has been indicated, however, that before undertaking the extraction of molar teeth it is important to investigate the potential influence of the procedure on other molars, with particular consideration of their eruption path. This is due to the doubt as to the effect of the exact molar teeth extraction and their consequences. In light of this, This review was undertaken to investigate and compare the effect of first, second and the third molar teeth extraction and their subsequent dentofacial complex changes.

To analyse the amount of root resorption of mesially or horizontally impacted mandibular third molars after orthodontic uprighting treatment.

Twenty-four patients with an age range of 20∼26years old who had mesially/horizontally impacted third molars with complete root formation. And those with decayed or missing the mandibular first molar on the same side were selected. The lower third molars were uprighted and the extraction spaces closed. Root resorption was compared with paired t-test. The related risk factors for root resorption were compared with Pearson correlation analysis.

The average uprighting time was 10.00 months (4∼16months). The study showed that all the impacted third molars were uprighted and got satisfactory outcomes after treatment. Shortening in length of mandibular third molar roots was detected at the end of the treatment, but no statistically significant differences were found (P<0.05). Root resorption was correlated with the duration of uprighting and the distance that root moved.

Impacted mandibular third molars were uprighted and the amount of root resorption of third molar after treatment was not increased. The duration of uprighting and the distance that root moved influence the degree of root resorption.

The development of third molars can be evaluated with medical imaging to estimate age in subadults. The appearance of third molars on magnetic resonance imaging (MRI) differs greatly from that on radiographs. Therefore a specific staging technique is necessary to classify third molar development on MRI and to apply it for age estimation.

To develop a specific staging technique to register third molar development on MRI and to evaluate its performance for age estimation in subadults.

Using 3T MRI in three planes, all third molars were evaluated in 309 healthy Caucasian participants from 14 to 26 years old. According to the appearance of the developing third molars on MRI, descriptive criteria and schematic representations were established to define a specific staging technique. Two observers, with different levels of experience, staged all third molars independently with the developed technique. Intra- and inter-observer agreement were calculated. The data were imported in a Bayesian model for age estimation as described by Fieuws et al. (2016). This approach adequately handles correlation between age indicators and missing age indicators. It was used to calculate a point estimate and a prediction interval of the estimated age. Observed age minus predicted age was calculated, reflecting the error of the estimate.

One-hundred and sixty-six third molars were agenetic. Five percent (51/1096) of upper third molars and 7% (70/1044) of lower third molars were not assessable. Kappa for inter-observer agreement ranged from 0.76 to 0.80. For intra-observer agreement kappa ranged from 0.80 to 0.89. However, two stage differences between observers or between staging sessions occurred in up to 2.2% (20/899) of assessments, probably due to a learning effect. Using the Bayesian model for age estimation, a mean absolute error of 2.0 years in females and 1.7 years in males was obtained. Root mean squared error equalled 2.38 years and 2.06 years respectively. The performance to discern minors from adults was better for males than for females, with specificities of 96% and 73% respectively.

Age estimations based on the proposed staging method for third molars on MRI showed comparable reproducibility and performance as the established methods based on radiographs.

To analyse the effect of first and second premolar extractions on eruption space for upper and lower third molars and on third molar position and angulation during orthodontic treatment.

The sample consisted of 296 patients of which 218 patients were orthodontically treated without extraction and 78 patients with extraction of first or second premolars. The eruption space for third molars was measured on pre- and posttreatment lateral cephalograms, whereas the angulation, vertical position, the relation with the mandibular canal and the mineralization status of third molars were evaluated using pre- and posttreatment panoramic radiographs. All data were statistically analyzed.

The increase in eruption space and the change in vertical position of upper and lower third molars significantly differed between patients treated with and without premolar extractions, whereas the change in angulation, relationship with the mandibular canal and mineralization status of the third molars did not significantly differ between patients treated with and without premolar extractions.

The retromolar space and the position of third molars significantly change during orthodontic treatment in growing patients. Premolar extractions have a positive influence on the eruption space and vertical position of third molars, whereas they do not influence the angular changes of third molars. Due to the retrospective character of the study, these conclusions should be carefully considered. Further prospective research is necessary for better insights into this complex topic.

This study stresses the importance of considering the possible effects of orthodontic treatment on third molars during treatment planning.

Highly processed diets eaten by postindustrial modern human populations coincide with higher frequencies of third molar impaction, malocclusion, and temporomandibular joint disorders that affect millions of people worldwide each year. Current treatments address symptoms, not causes, because the multifactorial etiologies of these three concerns mask which factors incline certain people to malocclusion, impaction, and/or joint issues. Deep scientific curiosity about the origins of jaws and dentitions continues to yield rich insights about the developmental genetic mechanisms that underpin healthy craniodental morphogenesis and integration. Mounting evidence from evolution and development (Evo-Devo) studies suggests that function is another mechanism important to healthy craniodental integration and fit. Starting as early as weaning, softer diets and thus lower bite forces appear to relax or disrupt integration of oral tissues, alter development and growth, and catalyze impaction, malocclusion, and jaw joint disorders. How developing oral tissues respond to bite forces remains poorly understood, but biomechanical feedback seems to alter balances of local bone resorption and deposition at the tooth-bone interface as well as affect tempos and amounts of facial outgrowth. Also, behavioral changes in jaw function and parafunction contribute to degeneration and pain in joint articular cartilages and masticatory muscles. The developmental genetic contribution to craniodental misfits and disorders is undeniable but still unclear; however, at present, human diet and jaw function remain important and much more actionable clinical targets. New Evo-Devo studies are needed to explain how function interfaces with craniodental phenotypic plasticity, variation, and evolvability to yield a spectrum of healthy and mismatched dentitions and jaws.

To test in the maxilla and mandible for an association between stage of third-molar (M3) mineralization and space in the jaws for M3 eruption. Mineralization is hypothesized to be delayed not only for impacted M3s but also for M3s with eruption space less than their mesiodistal crown diameter.

Retrospective cone beam computed tomography (CBCT) scans of 37 females and 32 males aged 17-24 years, for a total sample of 197 upper and lower M3s, were used to assess the status of M3 eruption and measure the M3 crown diameter (CD) relative to the length of the retromolar space (RS). Stage of M3 mineralization was then compared between impacted and erupting M3s as well as between two conditions of relative eruption space (RS/CD ≥ 1 versus RS/CD < 1) using Mann-Whitney U tests.

Impacted M3s were at significantly earlier (delayed) stages of mineralization compared to erupting M3s. Mineralization was also delayed for M3s with eruption space less than their mesiodistal crown diameter (e.g. RS/CD < 1). A moderate positive correlation between stage of M3 mineralization and space was seen in both jaws, and was stronger in the mandible.

Our study shows for the first time that stage of M3 mineralization is associated not only with impaction but also with amount of retromolar space, and that these associations are consistent in upper and lower jaws. Present findings underscore that M3 mineralization stage may be a clinically useful predictor of M3 impaction that thus merits further investigation.