Permanent Molars Research Articles

Literature review and case study: unveiling the complexities of mandibular second molar with three distal canals.

The occurrence of morphological deviations in root canal anatomy is challenging and can influence treatment outcomes. While mandibular second molars typically have 2 roots and 3 canals, a unique case emerged in a 23-year-old Indian male with a symptomatic permanent left mandibular second molar showing three distal, two mesial canals, and two roots. The tooth presented as non-mobile but tender on percussion. The patient was diagnosed with symptomatic irreversible pulpitis with symptomatic apical periodontitis. The presence of mid distal canal was radiographically and visually confirmed with the aid of limited FOV cone-beam computed tomography and the dental operating microscope. Successful nonsurgical root canal treatment with 6-month follow-up has been documented in this case report.

Three-dimensional finite element analysis of occlusal stress on maxillary first molars with different marginal morphologies restored with occlusal veneers

BackgroundThere are differences in the research results regarding which edge design of occlusal veneers can achieve the best long-term success rate as a relatively new fixed prosthesis restoration method. Further research is needed. The three-dimensional finite element method was used to conduct stress analysis on occlusal veneers of maxillary first permanent molars with different thicknesses and margin preparation designs. The aim of this study was to provide mechanical research evidence and a reference for exploring standardized clinical protocols for the design of occlusal veneer restorations of maxillary first molars.MethodA 3Shape (Intraoral Scanner) was used to scan the maxillary first molar teeth in vitro, after which 3D printing was carried out. Three different edge designs were applied to identical teeth: straight-beveled finishing line(SFL), chamfer finishing line(CFL), and standard cuspal inclination(SCI). Preparation was carried out with a thickness of 0.5 mm. Using the surface deformation feature, the occlusal veneer was thickened to 0.5 mm and 1.0 mm, and periodontal ligaments were added. They were then placed into the upper and lower jaws and dental arches. Finite element analysis was performed after applying bite force dispersion to the loading area on the mandible following dynamic contact.Results(1) As the thickness increased, the maximum Von Mises stress in the occlusal veneers SFL and CFL also increased, while the SCI exhibited the opposite trend. (2). The trend of the maximum Von Mises stress in the adhesive layer decrease gradually with increasing thickness of the occlusal veneer. The stresses of the SFL and CFL is concentrated primarily at the edge position below the functional cusp, resulting in relatively low adhesive stress. However, in the SCI group, the maximum stress at the edge of the adhesive layer exceeds the maximum shear strength of commonly used adhesives.ConclusionsUnder the experimental conditions, the mechanical properties of the maximum Von Mises stress in the SFL, CFL, and SCI occlusal veneers meet clinical needs. Incorporating the minimally invasive concept of tooth preservation, a thickness of 1.0 mm are optimal for glass ceramic occlusal veneers on maxillary first molars.

To Treat or to Extract Necrotic First Permanent Molars Between 8 and 12 Years of Age: A Retrospective Cohort Study.

Background: First permanent molars (FPM) are highly susceptible to decay before the age of 15. When they are severely affected, the decision between conservation and extraction arises, particularly considering the potential for the second permanent molar (SPM) to replace the FPM. This cohort study aimed to evaluate clinical practices regarding FPM pulp necrosis treatment in children aged eight to twelve in two hospital departments in the Paris region. A second objective was to evaluate the one-year outcomes of the two therapies. Methods: A retrospective analysis was conducted using computerized billing software to identify patients aged eight to twelve who underwent either extraction or root canal treatment (RCT). Data collected included sex, age, arch involved, number of decayed surfaces, presence of Molar Incisor Hypomineralization (MIH), presence of infection, and treatment type. Results: A total of 66 patients were included, representing 61 extracted teeth and 23 RCT. Three main decision criteria were identified: presence of MIH (p < 0.005), extent of decay (p < 0.05), and SPM Nolla's stage. A total of 48% of the patients were seen at one year. A total of 16 of the 32 extractions and five of the nine RCTs had favorable evolution (p = 1). Conclusions: The question of whether to perform RCT or extraction of necrotic FPM in children aged eight to twelve is difficult to assess. It appears that five criteria need to be considered before the decision: possibility of long-term sealed coronal reconstruction, SPM Nolla's stage, follow-up possibilities, arch concerned, and presence of third permanent molar.

Prevention of occlusal caries using VanishTM XT: an 18-month follow-up randomized clinical trial

AimTo evaluate the effectiveness of a light curable resin-modified glass ionomer varnish (VanishTM XT) in the prevention of occlusal caries compared to topical fluoride varnish in newly erupted first permanent molars over 18 months.MethodsA randomized controlled clinical trial was conducted using a split-mouth design. A total of 53 participants aged 6–9 years with 97 pairs of caries-free newly erupted first permanent molars were enrolled in the study. Each molar in the pair was randomly assigned either to the experimental group, which received the VanishTM XT Extended Contact Varnish, or to the control group, which received topical fluoride varnish (VanishTM 5% Sodium Fluoride White Varnish). Follow-ups were performed at 6, 12, and 18 months to evaluate dental caries development.ResultsAt the 6-month follow-up, caries development was significantly higher in the control group (7.8%) than that in the experimental group (0%) (P = 0.031). At the 12-month follow-up, significantly (P = 0.012) more occlusal caries developed in the control group (12.2%) compared to the experimental group (1.2%). At the 18-month follow-up, significantly (P = 0.002) more occlusal caries developed in the control group (14.3%) compared to the experimental group (1.1%).ConclusionCompared to fluoride varnish, VanishTM XT was significantly more effective in preventing caries on the occlusal surfaces of newly erupted first permanent molars at 6, 12, and 18 months.Trial registrationRegistration number at ClinicalTrials.gov: NCT04579536 on 08/10/ 2020, retrospectively registered.

Enhancing pediatric comfort: a comprehensive approach to managing molar-incisor hypomineralization with preemptive analgesia and behavioral strategies.

Preemptive analgesia is an important strategy used in pediatric dentistry to intercept pain signals in neural pathways early, thus mitigating the perception of pain and enhancing overall patient comfort. Pedodontists often encounter challenges in conducting the therapy and managing uncooperative patients, when addressing enamel defects of the Molar-incisor hypomineralization (MIH) type. The aim of this study is to demonstrate the impact of preemptive analgesia on optimizing behavioral management and restorative treatment strategies for immature permanent molars exhibiting severe MIH and Treatment need index 4 (TNI), through the effective control of pain. This study comprised 27 cases with MIH level 3 Posteruptive breakdown (PEB), indicating post-eruptive enamel breakdown, with initial hypersensitivity scores exceeding 4 on the Wong-Baker Scale, was conducted over 12 months, between January 2023-January 2024. Data on pediatric patients aged between 5 years and 4 months and 7 years and 1 month with varying degrees of sensitivity in their permanent first molars before the completion of the eruption process were collected. Pain intensity was systematically evaluated at six specific time points: before and after the administration of analgesic medication as well as during restorative treatment using the Wong-Baker scale and data from the Face, Legs, Activity, Cry, Consolability index (FLACC). Statistical analysis for Wong-Baker scores and FLACC index indicated statistical significance (p < 0.05) for Mann-Whitney and Wilcoxon tests, respectively t-test. The comparison of mean scores recorded before and after preemptive analgesia during rotary instrumentation moments for the Wong-Baker index (4 > 0.29) and for the FLACC index (8.47 > 1.71) indicates the positive influence of administering ibuprofen. In conclusion, preemptive analgesia, alongside standardized anesthesia, significantly improved intraoperative pain management and behavioral outcomes.

Effect of enzymatic chemo-mechanical agents on adhesion of composite resin to dentin of permanent teeth: an in vitro study.

To evaluate and compare the effect of two enzymatic chemo-mechanical caries removal agents with conventional caries removal using rotatory instruments on the adhesion of composite resin to dentin of permanent teeth. The sample comprised 30 permanent molars with caries lesions extending to the dentin, randomly distributed into three groups (n = 10 each): 1-Caries removal with rotary instruments (control group); 2-Caries removal with Papacárie Duo® (F&A Laboratório Farmacêutico, São Paulo, Brazil); 3-Caries removal with Brix 3000™ (Brix S.R.L., Carcarañá, Argentina). After caries removal, the specimens were rinsed and dried. Scotchbond Universal™ adhesive (3M, Saint Paul, Minnesota, USA) was actively applied in self-etch mode and light-cured. Resin composite increments were applied using a silicone mold (3 × 3 × 2mm) and light-cured. Shear bond strength (MPa), work-to-debonding (J/m2), and shear modulus (kPa) were evaluated. For statistical analysis, the level of significance was set at 5%. The control group presented significantly higher shear bond strength values (8.50 ± 2.69MPa) compared to the Brix 3000™ group (5.72 ± 1.55MPa, p = 0.008). There were no significant differences between Papacárie Duo® (6.66 ± 0.86MPa) and the other groups (p > 0.05). Regarding work-to-debonding, the Papacárie Duo® group had a significantly higher result (2944.41 ± 450.21J/m2) than the Brix 3000™ group (1189.41 ± 504.13J/m2, p < 0.001) and the control group (967.10 ± 270.01J/m2, p < 0.001). Concerning shear modulus, the control group showed a significantly higher result (558.67 ± 168.96kPa) than the Brix 3000™ group (339.79 ± 143.78kPa, p = 0.008) and the Papacárie Duo® group (223.04 ± 127.30kPa, p < 0.001). While the application of Papacárie Duo® did not negatively affect composite resin adhesion to dentin of permanent teeth, the application of Brix 3000™ reduced adhesive forces, potentially limiting its clinical use. Further investigations are warranted to elucidate the effects of these materials on dentin substrate, particularly through clinical studies.

Restorative options for permanent molars severely affected by MIH

Restorative options for permanent molars severely affected by MIH

Deep caries and pulp exposures management preferences in permanent teeth: A survey amongst Spanish dentists.

To assess Spanish dentists' management preferences for deep caries removal and exposed pulps in permanent teeth. A web-based open and anonymous survey was distributed by social media and a specific website for this project amongst dentists practicing in Spain. The questionnaire comprised 40 questions, divided into five sections: (1) demographic data and professional activity; (2) carious tissue removal; (3) decision-making regarding pulp exposure; (4) direct pulp capping and (5) pulpotomy procedures in permanent teeth. Results were descriptively analysed. Logistic regression (95% CI) analyses and X2 tests were carried out. A total of 538 responses were received. Half the respondents (53.7%) preferred to perform complete caries excavation for shallow and moderate carious dentin lesions, and selective excavation to firm dentin for deep lesions (57.8%). Selective removal to soft dentin and stepwise removal were much less indicated (15.4% and 10.9%, respectively). Exposed pulps in asymptomatic teeth were treated by direct pulp capping (over 80%), decreasing in the presence of reversible pulpitis symptoms (57.1%). If irreversible pulpitis was diagnosed, a pulpectomy would be performed by 53.5% and 89.9% of the respondents in, respectively, immature and mature teeth. Pulpotomy was performed routinely only by 26.4% of the clinicians. Patients' attitudes and priorities were the most relevant criteria when performing direct pulp capping and pulpotomy, together with the history of pain and the presence of bleeding. Regarding the clinical procedure, dry cotton was preferred to obtain haemostasis and Biodentine was the material of election. Caries removal preferences and management of pulp exposure by dentists practicing in Spain deviated from vital pulp treatment guidelines, mainly regarding indications and case selection. Pulp exposure was managed by direct pulp capping in asymptomatic cases, whilst immature permanent molars favoured the indication of pulpotomy when pulpitis was diagnosed. Most clinicians used hydraulic calcium silicate cement, specifically Biodentine, to perform vital pulp treatments. Postgraduate formation and continuing education in caries lesions management and vital pulp treatments were consistently related to more conservative and updated decisions.

Effectiveness of Chewing Gum After Water Rinsing in Removing Remnants of Sticky Cookies From Posterior Teeth-A Prospective Interventional Study.

To evaluate the effectiveness of chewing sugarless gum (SG) after water-rinsing in removing retained Oreo chocolate cookies (CC) from occlusal surfaces of teeth with and without fissure-sealant (FS). A prospective study was performed on healthy children receiving prophylaxis at the paediatric-dentistry department. Immediately afterward, they chewed two CC. The occlusal surfaces of their posterior teeth were photographed 3 times: after 10 min, after 1 min of water-rinsing and after 4 min of chewing SG. An independent dentist screened all photos for the presence (partial or complete) or the absence of retained CC. Participants included 28 children 7-14-year-old, with 100 primary and 214 permanent molars, of which, 150 teeth had FS. After chewing two CC, 290 (92.4%) teeth had retained CC. Water-swishing removed all, partial or none of the CC in 23%, 72.4% and 4.6% of the teeth, respectively. The effectiveness of chewing SG in completely removing retained CC was significantly higher than water-rinsing (p < 0.001), OR = 43.83, Cramer's V value = 0.871, suggesting a very strong correlation. The presence of FS raised the probability of completely removing retained CC after SG or water-rinsing (p < 0.001, OR = 107.7 and 25.9), with Cramer's V = 0.66 and 0.57, respectively, means a very strong association, as compared to teeth without (For both p < 0.001). Chewing gum for 4 min was significantly more effective than water-rinsing for 1 min in removing retained CC. Moreover, FS considerably decreased the probability of retained CC on occlusal surfaces and increased the effectiveness of SG in removing it.

Predictability of Maxillary Expansion with Invisalign® First: Treatment Planning vs. Outcome

The aim of this study is to retrospectively investigate the predictability of maxillary arch expansion with Invisalign ® First in mixed dentition. In a sample of 64 treated patients, 3D digital models from the ClinCheck® software were compared with post-treatment digital models. Predicted maxillary expansion was related to the final outcome of expansion. At the cuspidal level, there was observed a predictability of 59.68% for deciduous canines, 63.77% for first deciduous molars, 66.99% for second deciduous molars, and 55.61% for first permanent molars. At the gingival level, there was observed a predictability of 49.87% for deciduous canines, 53.11% for first deciduous molars, 53.36% for second deciduous molars, and 45.16% for first permanent molars. The difference between the predicted and achieved expansion was statistically significant (p &lt; 0.05). Within the present limitations, our results suggest that, with Invisalign® First, it is possible to expand the upper arch in mixed dentition in an effective and predictable way. Clear aligners could represent a new and valid alternative for arch expansion in growing patients.

The impact of a rural school-based oral health intervention among primary schoolchildren in Armenia

Abstract Objectives Oral health (OH) interventions are shown to be effective in improving children’s OH status and behavior. This study evaluated the effectiveness of a school-based OH intervention combined with OH educational activities on rural schoolchildren’s OH status and behavior in a rural setting in Armenia. Methods The study population were primary schoolchildren of Mrgashat village, Armavir province, Armenia, and their parents. The intervention included sealant application to eligible permanent molars of children and fluoridization of their teeth twice a year over a two-year period. Educational activities included a training session for children and their parents, and distribution of educational materials among them. Baseline (BL) and follow-up (FU) assessments were conducted before and after the intervention (in 2022 and 2024) to evaluate its impact. Both assessments included clinical examination of children’s OH status by calculating their DMFT/dmft index, and telephone survey among parents on OH knowledge and behavior. The changes in DMFT/dmft index and OH knowledge and behavior scores were measured using paired t-test. Results Overall, 94 children and their parents participated in both BL and FU assessments. There was no significant change in the parental OH knowledge score: 77.4% (SD 14.0) at the BL and 78.7% (SD 13.2) at the FU. Yet, children’s OH behavior score increased significantly: from 44.9% (SD 18.2) at the BL to 60.0% (SD 15.4) at the FU (p &amp;lt; 0.001). Children’s DMFT/dmft index also improved significantly: from 7.31 at the BL to 5.09 at the FU assessment (p &amp;lt; 0.001). Conclusions The study demonstrated the effectiveness of the OH intervention in improving children’s OH status and behavior. Therefore, we recommend expansion of the intervention with inclusion of more rural sites in Armenia, and targeting primary schoolchildren, considering the importance of timely preventive interventions and early development of healthy habits for better OH later in life. Key messages • Oral health interventions among primary schoolchildren covering awareness raising and carries prevention activities result in positive changes in children’s oral health habits and teeth health. • Expansion of this type of interventions with inclusion of new rural sites and conduction of further assessments to explore the long-term effects of such interventions are recommended.

Spontaneous space closure after extraction of young first permanent molar. Retrospective cohort study.

Early compromised first-permanent-molar (FPM) extraction can adversely affect occlusion. However, the current literature does not provide sufficient support for definitive early extraction outcome. This cohort study aimed to evaluate the pattern of post-FPM extraction spontaneous space closure and its pre-extraction indicators. Patients of 7-13 years, with compromised FPM at three-tertiary-centers between 2015 and 2019 were retrospectively screened. Pre-extraction indicators were evaluated (extraction location, direction of the second permanent molar (SPM) long-axis, and SPM Demirjian development stage). Spontaneous space closure pattern was evaluated clinically and radiographically using the American Board of Orthodontics (ABO) grading system. In total, 112 FPMs (73-patients) were identified and five (4.5%) of the extraction sites showed favorable combined-ABO-scores. Distal direction of the SPM long-axis in the maxillary arch significantly decreased the relative risk (RR) of having a SPM rotation/alignment ABO score-1 (P = 0.002; RR = 0.64). For the mandibular arch, Demirjian stage D and E significantly decreased the RR of having ABO score-1 for spacing between the SPMs and second premolars (P = 0.029; RR:0.57, P = 0.004; RR:0.53, respectively) and vertical dimension (P = 0.02; RR = 0.53). The direction of the SPM long-axis and its developmental stage are key indicators of the favorable outcome pattern of spontaneous space closure after FPM early extraction.

Relationship of incidence of radix entomolaris and C-shaped canal in mandibular molars using CBCT: A multi-centre study.

This study aimed to evaluate the relationship of incidence between radix entomolaris (RE) in permanent mandibular first molars (FM) with C-shaped canal (CSC) in permanent mandibular second molars (SM). A total of 1015 cone-beam computed tomography (CBCT) images of permanent mandibular molars from Malaysian patients were collected retrospectively and analysed by researchers from seven dental schools in Malaysia trained in CBCT technology. The presence and absence of RE and CSC were scored as 'yes' or 'no'. The prevalence of FM with RE was 21.2% and SM with CSC was 37.9%. The co-occurrence of RE and CSC in the same quadrant was 6.5% (OR = 1.497, p = 0.014). Female, Chinese and samples from Eastern Peninsular Malaysia were associated with CSC in SM (p < 0.05). The increased appearance of CSC in SM when RE is present in FM makes it imperative for clinicians to be vigilant during examination and diagnosis to prevent potential endodontic mishaps.

Does selective root canal retreatment preserve the tooth’s fracture resistance? An ex-vivo study

ObjectivesTo assess the tooth’s fracture resistance when submitted to a selective root canal retreatment compared to the conventional approach.Methods33 intact permanent mandibular first molars were selected according to specific criteria. After teeth mounting, the primary root canal treatment was conducted and followed by thermo-mechanical aging procedures to mimic a few clinical conditions. The specimens were randomly divided into three groups (n = 11); a control group in which intact teeth were used and two experimental groups according to the retreatment approach: conventional non-surgical retreatment (Conventional-NSR), and selective non-surgical retreatment (Selective-NSR). Later, the teeth were submitted to a final thermo-mechanical aging procedure and tested regarding their fracture resistance (static fracture test). The maximum load to fracture was recorded as were the types of failure modes (repairable or non-repairable fracture). A proper statistical analysis was conducted, considering a significance level of 5%.ResultsThe Conventional-NSR group showed a mean failure load of 867.7 ± 108.9 N while the Selective-NSR group had 1106.8 ± 159.8 N (P = 0.012). Both retreatment groups showed significantly lower results when compared to the control group. Additionally, the Conventional-NSR group showed higher proportions of non-repairable fractures (54.5%) when compared to both the Selective-NSR (36.4%) and control (18.2%) groups.ConclusionsSelective root canal retreatment preserved the tooth’s fracture resistance compared to the conventional retreatment approach.Clinical trial numberNon-applicable. Conducting the current experiment was limited to obtaining approval from the local Research Ethics Committee at the Faculty of Dentistry, Minia University (Committee No. 105, Registration No. 902, Date: 26/3/2024).

Evaluation of hard tissue characteristics and calcifications in pulp tissue of hypomineralized permanent molars using micro-computed tomography

ObjectivesTo determine and compare pulp volume, dentin mineral density, presence of microcracks, pulp stones, and accessory canals, as well as their localizations in root regions for hypomineralized and healthy teeth. DesignThis study included 60 extracted permanent molar teeth, categorized into hypomineralized and healthy groups (n = 30 each). The hypomineralized group comprised molar teeth with limited white, yellow, or brown opacities, post-eruptive breakdown, or extensive restoration or crown damage. The healthy group included caries-free molar teeth without these characteristics. Using 3D micro-computed tomography images pulp volume, dentin mineral density, and the presence and locations of microcracks, pulp stones, and accessory canals were determined for each group. Statistical analyses were conducted using Independent T-test and Chi-square test, with significance set at p < 0.05. ResultsThere was no statistically significant difference between the groups regarding pulp volume and microcracks (p ≥ 0.05). The number of accessory canals was significantly greater in the cervical (p = 0.011; p < 0.05) and middle (p = 0.010; p < 0.05) regions of the hypomineralized teeth than healthy teeth. Dentin mineral density was statistically higher in the apical, middle, and cervical root regions (p < 0.001; p < 0.05); however, the number of pulp stones was found to be greater in the cervical regions of healthy teeth compared with those with hypomineralization (p = 0.026; p < 0.05). ConclusionThere were lower dentin mineral density measurements, a decreased number of pulp stones in the cervical region, and a greater number of accessory canals in the middle and cervical regions of hypomineralized teeth compared with healthy teeth.

Hipomineralização molar-incisivo - HMI: relato de caso clínico

Molar Incisor Hypomineralization (MIH) is a qualitative defect in the dental enamel that affects one or more permanent molars, where the permanent incisors may also be involved. The objective of this work was to report a clinical case of Molar-Incisor Hypomineralization (MIH) following a choice of treatments according to the different severities present in the patient. The case report is of a patient, 12 years old, female, who attended the Pediatric Dentistry clinic of Faculdade do Amazonas - IAES accompanied by her guardian, with the following main complaint: “I want to remove these stains”. In the extra and intraoral examination, marked opacities ranging from yellow to brown in elements 26 and 17 and white to yellow in dental elements 11, 21, 23 were observed. 11, 21, and 23 and proservation with fluoride varnish after previous prophylaxis on molars 17 and 26. It is concluded that it is very important for the dental surgeon to know how to identify MIH in order to choose the best treatment for each patient with different levels of severity. And in this way, we provide satisfactory results both in the execution of the treatment of choice and in the patient's life, remedying her main complaint.

Chromatic Adaption of Two Universal Composites: Spectrophotometric Analysis

Objective: The purpose of this study was to evaluate the chromatic adaptability and color stability of two different composite resins, Omnichroma and Estelite Bulk-Fill Flow, in Class V restorations at different times. Materials and methods: Standardized Class V cavities were prepared on the labial surface of 34 extracted intact and noncarious human permanent molars. The dental elements were randomly divided into two groups according to the resin composite material. Group 1 was restored with Omnichroma (Tokuyama Dental Corporation Inc., Tokyo, Japan) and Group 2 was restored with Estelite BulkFill Flow Universal (Tokuyama Dental Corporation Inc., Tokyo, Japan). Color properties were assessed using a spectrophotometer, SpectroShadeTM Micro (MHT Optic Research, Niederhasli, Switzerland), at baseline (T0), immediately after Class V restoration (T1), 24 h after restoration (T2) and after thermocycling (T3) (ISO/TS 11405, 2015 protocol). Color difference (ΔE) was analyzed with a Student’s t-test and a Wilcoxon–Mann–Whitney test to evaluate the differences, in terms of chromatic adaptability, between the two materials (inter-group analysis) while Kruskal–Wallis test e Two-way ANOVA statistical tests were used to evaluate the color stability of each material over time (intra-group analysis). Results: Regarding the inter-group analysis, there were no statistically significant differences between the two materials in all the comparisons: T0–T1 (p = 0.9025), T0–T2 (p = 0.2779), T0–T3 (p = 0.4694). Moreover, both groups showed an average ΔE &gt; 2. In the intra-group analysis, no statistically significant differences were observed in either Group 1 (p = 0.954) or Group 2 (p = 0.8654). Conclusions: The in vitro color matching, assessed by spectrophotometry, of the two tested resin composites does not vary at different time intervals. Furthermore, even though both composites use different mechanisms to produce the color the human eye perceives, they show very similar chromatic adaptability.

Incidence and effect of an extra root on the crown morphometry of the maxillary second molars among Malaysian Mongoloids.

This study aimed to investigate whether the presence of two palatal roots on permanent maxillary second molars (MSMs) can affect the crown size and crown's buccolingual and mesiodistal diameters. A retrospective study was conducted using 592 CBCT scans to investigate 1120 MSMs of Mongoloid Malaysians. 3D models were created to assess the four-rooted MSMs and other related teeth carefully. Crown size and crown's buccolingual and mesiodistal diameters were measured for the four-rooted MSM, the adjacent maxillary first molar (MFM), and their antimeres to investigate the effect of the presence of an extra root on the size and morphological features of the crown of these associated teeth. Only six out of the 1120 MSMs displayed four roots (0.53%). The incidence was 0.67% (2/298) for the Malay males and 0.4% (1/247) for the Malay females, with the Malay male having a bilateral occurrence of four-rooted MSM. The incidence was 0.34% (1/294) for the Chinese males, while 0.71% (2/281) was detected in Chinese females. Interestingly, the four-rooted MSMs showed a wider mesiodistal distance than their three-rooted antimeres in three out of four cases. The presence of two palatal roots may also increase the crown's buccolingual diameter. The presence of anatomical variations and the dramatic change in crown measurements can be good indicators of the presence of extra roots, including in some of their related neighbours. This might help dentists to take precautionary measures when performing tooth extractions and endodontic therapy.

Spontaneous space closure after extraction of permanent first molars in children and adolescents: a systematic review and meta-analysis.

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).

The second primary molar in the lower jaw in cases of agenesis of the second premolar; use it or break it?

In cases of agenesis of the mandibular second premolar, a choice can be made from among several treatment options. Besides preserving the second primary molar, it can be decided to close the diastema orthodontically, following extraction of the primary molar. This can be done in several ways: full or partial (hemisection) removal of the primary molar. The procedure for a hemisection initially consists of removing only the distal part of the relevant primary molar, in order to preserve the breadth of the alveolar process and to enable spontaneous mesialization of the first permanent molar. Secondly, the mesial part of the primary molar is removed.