Oxygen regulates epithelial stem cell proliferation via RhoA-actomyosin-YAP/TAZ signal in mouse incisor.

Stem cells are maintained in specific niches that strictly regulate their proliferation and differentiation for proper tissue regeneration and renewal. Molecular oxygen (O2) is an important component of the niche microenvironment, but little is known about how O2 governs epithelial stem cell (ESC) behavior. Here, we demonstrate that O2 plays a crucial role in regulating the proliferation of ESCs using the continuously growing mouse incisors. We have revealed that slow-cycling cells in the niche are maintained under relatively hypoxic conditions compared with actively proliferating cells, based on the blood vessel distribution and metabolic status. Mechanistically, we have demonstrated that, during hypoxia, HIF1α upregulation activates the RhoA signal, thereby promoting cortical actomyosin and stabilizing the adherens junction complex, including merlin. This leads to the cytoplasmic retention of YAP/TAZ to attenuate cell proliferation. These results shed light on the biological significance of blood-vessel geometry and the signaling mechanism through microenvironmental O2 to orchestrate ESC behavior, providing a novel molecular basis for the microenvironmental O2-mediated stem cell regulation during tissue development and renewal.

DISP1 deficiency: Monoallelic and biallelic variants cause a spectrum of midline craniofacial malformations.

PURPOSE: DISP1 encodes a transmembrane protein that regulates the secretion of the morphogen, Sonic hedgehog, a deficiency of which is a major cause of holoprosencephaly (HPE). This disorder covers a spectrum of brain and midline craniofacial malformations. The objective of the present study was to better delineate the clinical phenotypes associated with division transporter dispatched-1 (DISP1) variants. METHODS: This study was based on the identification of at least 1 pathogenic variant of the DISP1 gene in individuals for whom detailed clinical data were available. RESULTS: A total of 23 DISP1 variants were identified in heterozygous, compound heterozygous or homozygous states in 25 individuals with midline craniofacial defects. Most cases were minor forms of HPE, with craniofacial features such as orofacial cleft, solitary median maxillary central incisor, and congenital nasal pyriform aperture stenosis. These individuals had either monoallelic loss-of-function variants or biallelic missense variants in DISP1. In individuals with severe HPE, the DISP1 variants were commonly found associated with a variant in another HPE-linked gene (ie, oligogenic inheritance). CONCLUSION: The genetic findings we have acquired demonstrate a significant involvement of DISP1 variants in the phenotypic spectrum of midline defects. This underlines its importance as a crucial element in the efficient secretion of Sonic hedgehog. We also demonstrated that the very rare solitary median maxillary central incisor and congenital nasal pyriform aperture stenosis combination is part of the DISP1-related phenotype. The present study highlights the clinical risks to be flagged up during genetic counseling after the discovery of a pathogenic DISP1 variant.

Diagnosing celiac disease in children using oral manifestations.

PURPOSE: Celiac disease (CD) may be frequently undiagnosed due to the absence of characteristic gastroenterologic symptoms in many CD patients. Our objective was to diagnose CD by utilizing documented oral manifestations such as Recurrent Aphthous Stomatitis (RAS) and Molar-Incisor Hypomineralization (MIH). METHODS: The study comprised sixty children who presented with complaints of RAS lesions. The MIH group consisted of 40 children, while the control group comprised 20 children without MIH lesions, ranging in age from 7 to 13 years. After the dental examination, all children were given a questionnaire to assess whether they had any previous history of general symptoms related to CD. Following that, diagnostic testing for celiac disease were conducted, including serological tests such as Tissue transglutaminase IgA (tTG-IgA), Endomysium Antibody (EMA), and Total IgA, as well as genetic tests for HLA-DQ2 and HLA-DQ8. RESULTS: The statistical analysis, conducted using Fisher's Exact, Yates' Continuity Correction, Fisher Freeman Halton, and Student's t tests, revealed no significant differences between the groups (p < 0.05). Within the MIH group, 3 children exhibited border tTG-IgA values, while another 3 had positive tTG-IgA results. Two of these 6 children had also positive EMA and HLA results. Following a biopsy procedure, these two children were ultimately diagnosed with celiac disease (CD). CONCLUSIONS: In this study, while children initially presented to the clinic with complaints of recurrent aphthous stomatitis (RAS), 2 children (5% of the MIH group) were diagnosed with CD shortly after the onset of MIH lesions. CD enhanced the likelihood of observing some oral manifestations particularly recurrent aphtous stomatitis and developmental enamel defects. We recommend that dentists be cautious about diagnosing CD when RAS lesions and DEDs and/or MIH lesions are present, whether or not other indications of this systemic disease exist.

The association between serum vitamin D status and dental caries or molar incisor hypomineralisation in 7-9-year-old Norwegian children: a cross-sectional study.

BACKGROUND: Research focusing on the association between serum vitamin D and oral health outcomes in children, such as dental caries and molar incisor hypomineralisation (MIH), shows inconsistent results. Previous studies have predominantly investigated dental caries and MIH as dichotomized outcomes, which limits the information on their distribution. In addition, the methods used for analysing serum vitamin D have varied. The present study aimed to investigate potential associations between serum vitamin D status measured by Liquid Chromatography with Tandem Mass Spectrometry (LC-MS/MS) and the prevalence, as well as the number of teeth, affected by dental caries or MIH among 7-9-year-old Norwegian children. METHODS: The study had a cross-sectional design and included 101 children aged 7-9 years. Serum 25-hydroxyvitamin D (25(OH)D) was measured and included as continuous (per 25 nmol/l) and categorised (insufficient (< 50 nmol/l) and sufficient (≥50 nmol/l)) exposure variables. Adjusted negative binomial hurdle models were used to investigate the potential associations between serum vitamin D and the oral health outcomes (dental caries and MIH) adjusted for sex, age, body mass index, season of blood draw, and mother's educational level. RESULTS: Of the 101 children in the total sample, 27% had insufficient vitamin D levels (< 50 nmol/l). The descriptive analysis indicated that the children with insufficient vitamin D levels had a higher prevalence (33.3%) and a higher number of teeth affected by dental caries (mean (SD) = 0.7 (1.4)), compared to children with sufficient levels of vitamin D (21.6% and mean (SD) = 0.4 (0.8), respectively). The same holds for MIH, with a higher prevalence (38.5%) and a higher number of teeth affected (mean (SD) = 1.2 (2.3)), compared to children with sufficient levels of vitamin D (30.1% and mean (SD) = 0.8 (1.6), respectively). However, in the adjusted hurdle model analysis, neither the prevalence or number of teeth affected by caries or MIH showed statistically significant associations with having insufficient or lower vitamin D levels. CONCLUSIONS: Vitamin D status was not significantly associated with the prevalence and number of teeth affected by caries and MIH among the participating children. Large prospective studies with multiple serum vitamin D measurements and oral examinations throughout childhood are warranted to elucidate the relationship.

Association of Molar Incisor Hypomineralization with Hypomineralized Second Primary Molars: An Updated Systematic Review with a Meta-Analysis and Trial Sequential Analysis.

INTRODUCTION: There is a correlation between molar incisor hypomineralization (MIH) and hypomineralized second primary molars (HSPM), but this relationship has not been definitively confirmed. The purpose of this systematic review and meta-analysis was to reevaluate whether children with HSPM are more affected by MIH than non-HSPM children. METHODS: A systematic search was conducted in four databases (PubMed, Embase, Web of Science, and the Cochrane Library) for literature, published up to December 2022. Two independent reviewers conducted the study search and screening, quality assessment, and data extraction according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The risk-of-bias assessment of all included cohort studies and case-control studies was assessed by the Newcastle-Ottawa Scale (NOS), and cross-sectional studies were assessed using the Agency for Healthcare Research Quality (AHRQ) scale. RevMan 5.4 software was used for all data analyses, with odds ratios (ORs) and 95% confidence intervals (CIs) as the effect measures. Sensitivity and subgroup analyses were conducted to identify the potential sources of heterogeneity among the studies. Publication bias was tested and corrected by funnel plots and Egger's test. Trial sequential analysis (TSA) was performed using TSA 0.9.5.10 Beta software to control for type-1 and type-2 errors. RESULTS: A total of 12 studies involving 8,944 children were included in this meta-analysis. Compared with the non-HSPM group, the HSPM group had an increased likelihood of MIH (OR = 10.90, 95% CI = 4.59-25.89, p < 0.05). All the included studies were of moderate-to-high quality. TSA and sensitivity analyses suggested the robustness of this outcome. CONCLUSION: This systematic review demonstrated a certain correlation between HSPM and MIH, suggesting that HSPM can play a predictive role in the occurrence of MIH. Further high-quality, multicenter, and large-sample longitudinal studies are highly recommended.

Variation of chin morphology and mandibular incisor length in different facial divergence patterns: New insights from CBCT records.

AIM: Evaluate constitutional differences in chin morphology and volume, and mandibular tooth size, between different facial divergence patterns. MATERIALS AND METHODS: The sample consisted of 284 pretreatment cone beam computed tomography (CBCT) images of growing and non-growing patients who were stratified into 4 groups based on mandibular plane inclination to cranial base (SN) angle. Linear and angular measurements were made on the lateral CBCT images: mandibular lateral incisor crown (I-C) total (I-A) lengths, the distances between point D (centre of symphysis) and both incisor apex (D-A) and menton (D-Me) and between cemento-enamel junction and menton (CEJ-Me); chin width at the level of the central incisor apex (CWA) and point D (CWD); and the angles of the anterior and posterior symphyseal slopes. The volume of the symphysis was measured using a specialized 3D imaging software. Group differences and associations between parameters were gauged through the three-way ANOVA analysis. RESULTS: I-C, I-A, D-A, D-Me and CEJ-Me were greater in the hyperdivergent group (p < .001). CWA and CWD were wider in the hypodivergent group (p = .003). Volume of the chin and inter-slope angles were similar in all groups (p > .05). The anterior slope angle decreased with hyperdivegence (p < .005) in opposite pattern to the posterior slope angle (p < .005). CONCLUSIONS: Shape differences in mandibular symphysis were observed between opposite divergence patterns. Mandibular incisors were longer with hyperdivergence and shorter with hypodivergence. However, chin volumes were similar across divergence groups. These findings underline the role of genetic and environmental factors that impact facial growth.

Apical incisor root resorption due to ectopic maxillary canine eruption: Association with time of diagnosis and type of intervention in a retrospective population-based cohort study.

OBJECTIVES: The primary aim was to study upper incisor severe apical root resorption (RR) related to ectopic canine eruption and its association with timing of diagnosis and type of intervention conducted. The secondary aim was to correlate resorption with other dental anomalies. MATERIALS AND METHODS: Digital journals and radiographic material of all ectopic maxillary canines registered in 2012 in the regional public paediatric dental clinics in the Council of Aarhus were inspected retrospectively. Data related to 10 variables were retrieved. Post-treatment radiographs were used for evaluation of incisor RR. RESULTS: A total of 260 ectopic maxillary canines were diagnosed in 2012. The majority were found in the 9-13-year-old age group (0.8% prevalence within the total population). In all, 244 canines were assessed for eligibility and 181 had adequate final radiographs for evaluation of RR. Among ectopic maxillary canines, 9.4% caused severe incisor RR to neighbouring teeth. Timely palpation for canine eruption significantly reduced the odds for upper incisor resorption by 80%. Multiple regression showed that when the permanent canine cannot be palpated and the deciduous has been extracted, delaying the first X-rays was associated with a 38% odds ratio increase for RR for each year of delay after the age of 10 years. No significant associations were found between incisor RR and intervention conducted or other dental anomalies. CONCLUSION: Palpation of erupting maxillary canines is crucial for timely diagnosis of ectopic eruption and initiation of treatment to avoid RR. If the canine cannot be palpated at 10 years of age, radiographic examination is highly recommendable.

Which are the clinical consequences of Molar Incisor hypomineralization (MIH) in children and adolescents? Systematic review and meta-analysis.

OBJECTIVE: This systematic review was conducted to address the following research question: "What are the clinical consequences (outcome) of Molar Incisor Hypomineralization (MIH) (exposure) in children and adolescents (population/patient)?". MATERIAL AND METHODS: After defining the strategy, a search was performed in different databases (MEDLINE via Pubmed, Cochrane Library, BBO, LILACS, Scopus, Web of Science, Embase) and Grey literature in August 2023. Cross-sectional observational studies that identified clinical consequences of MIH (dental caries, post-eruptive structural loss, atypical restorations, hypersensitivity and tooth extraction) were included. The risk of bias was assessed following the Joanna Briggs Institute protocol for cross-sectional studies. Meta-analyses were conducted for each outcome, taking into account the number of patients and teeth. The effect measure considered was the prevalence; random-effects model was adopted. Heterogeneity was assessed using I2 statistics and prediction intervals (PI). RESULTS: A total of 903 studies were identified; 41 were selected for qualitative analysis and 38 for quantitative analysis. Twenty eight studies were classified as presenting uncertain risk of bias, 11 as low risk and 3 as high risk of bias. The prevalence levels, ranked from highest to lowest and considering the tooth and patient units, respectively, were: caries lesions (0.252 - 95% CI 0.158-0.375; 0.512 - 95% CI 0.385-0.639); hypersensitivity (0.286 - 95% CI 0.190-0.407; 0.417 - 95% CI 0.197-0.674), post-eruptive fracture (0.125 - 95% CI 0.099-0.158; 0.257 - 95% CI 0.145-0.412); atypical restorations (0.048 - 95% CI 0.030-0.077; 0.167 - 95% CI 0.096 - 0.274); tooth extraction (0.012 - 95% CI 0.007-0.019; 0.090 - 95% CI 0.019 - 0.331). All meta-analyses resulted in heterogeneity greater than 85%, with the exception of the outcome "tooth extraction" according to the tooth unit (I2 = 57.83). This heterogeneity may be attributed to factors such as differences in the location where the study was realized, the socioeconomic conditions of the studied population, the asymmetric nature of MIH, and patient age. CONCLUSION: The most common consequences of MIH are caries lesions, hypersensitivity, and post-eruptive breakdown. (PROSPERO:CRD42020201410).

What can impact on the presence of carious lesions in first permanent molars? Revisiting the association between MIH and caries.

OBJECTIVE: Assess whether the independent variables (IV) such as number of MIH-affected molars, MIH severity, past caries experience, visible plaque index (VPI), gingival bleeding index (GBI), age, and gender affect the presence of caries lesion (DMF_s) in first permanent molars, considering or not atypical restoration in MIH-affected molars as a previous caries lesion. METHODS: A sample of 476 schoolchildren, aged 6-10 years, were evaluated for MIH and caries diagnosis, using the Severity Scoring System (MIH-SSS) and the International Caries Detection and Assessment System (ICDAS), respectively. From the ICDAS, the DF-s/ D-s and df-s were calculated. The Zero-inflated Negative Binomial Regression was used to evaluate the impact of the IV on the dependent variable, considering or not the restorative component in MIH-affected molars. RESULTS: When the presence of caries was evaluated with the restorative component, age, MIH severity and past caries experience had a significant impact on the dependent variable (R2 = 0.176). Without the restorative component in MIH-affected molars, only age and past caries experience were statistically significant (R2 = 0.167). CONCLUSION: Since in the case of MIH teeth restoration may be attributed to post-eruptive breakdown rather than previous caries lesions, in the present study MIH did not influence the presence of caries lesions in the MIH-affected molars showing that restoration is not an adequate parameter for measuring the historical occurrence of caries. CLINICAL RELEVANCE: The first permanent molars may not necessarily be at an increased risk of caries due to MIH if the etiological factors for caries development are effectively managed.

Effect of the filling technique on the filling removal from oval-shaped canals.

OBJECTIVES: This ex vivo study aimed to evaluate the influence of different filling techniques on the filling removal from oval root canals filled with bioceramic sealer. METHODS: Thirty-six mandibular incisors with single oval canals were filled with bioceramic sealer following the techniques (n = 12): single-cone, modified McSpadden, or continuous wave of condensation, and scanned by micro-computed tomography (micro-CT). The filling was removed using the Clearsonic ultrasound tip and Reciproc system up to the R40 instrument, and the working time was recorded. The teeth were scanned again by micro-CT. Percentage of remnant volume (mm³) of the filling material, dentin thickness, and root canal transportation were measured. The data was analyzed using parametric and non-parametric tests with a significance level of 5%. RESULTS: It took more time to remove the filling material using the continuous wave of condensation technique (p < 0.05), followed by the modified McSpadden and single-cone techniques. There was no difference (p > 0.05) when comparing the percentage of remaining filling material among the three groups, nor did it among the segments of each tooth. There was also no difference in the analysis of dentin thickness and transportation when comparing the groups (p > 0.05). CONCLUSIONS: The filling technique did not influence the amount of remaining filling material, dentin thickness, and transportation. The working time was longer with thermoplastic filling techniques. CLINICAL RELEVANCE: Endodontic retreatment in teeth filled with bioceramic sealers increases with their use. Several techniques are used to fill the root canals, thus, it is important to know whether the filling technique influences the non-surgical endodontic retreatment.

Micro-computed tomographic analysis of the morphology of maxillary lateral incisors.

OBJECTIVE: This study aimed to investigate the morphology of maxillary lateral incisors (MxLI) using micro-computed tomography (micro-CT). MATERIALS AND METHODS: The root canal configurations (RCC) of maxillary lateral incisors (MxLI) of a mixed Swiss-German population were examined using micro-CT, 3D imaging, and a 4-digit system code indicating the main root canal from coronal to apical thirds and the main foramina number. RESULTS: The most frequently observed RCC of MxLI were 1-1-1/1 (Vertucci I/Ve I, 80.0%), 1-1-2/2 (Ve V, 7.3%), 1-2-1/1 (Ve III, 6.4%), 2-1-1/1 (Ve II, 1.8%), and 1-1-1/2 (1.8%)(n = 110). Three additional RCC were observed less frequently (0.9%). The MxLI showed one physiological foramen in 89.1%, two in 9.1%, and seldom three (1.8%). Most accessory canals were identified in the apical third of a root (20.0%), and no accessory canals in 72.7% of the samples. CONCLUSIONS: Detailed information on the internal morphology of MxLI of a Swiss-German population is given. The most frequently observed RCC of MxLI is 1-1-1/1 (Ve I). However, accessory canals may occur in all apical thirds, and 20% of all teeth investigated showed a challenging RCC for clinical treatment. CLINICAL RELEVANCE: This study offers clinicians comprehensive data on MxLI morphology, emphasizing the significance of understanding varied RCC and accessory canal presence for improving root canal treatment outcomes. Over 25% of teeth exhibited complex RCC or accessory canals, influencing decisions during root canal treatment.

Comparison of transverse dimensional and incisor changes between wide and narrow orthodontic archwires: a randomized controlled trial.

OBJECTIVES: To clinically compare the effects of broader archwires to standard archwires, using conventional brackets in both cases, on the transverse and incisor changes in maxillary and mandibular arches during leveling and alignment. MATERIALS AND METHODS: Fifty-two patients presenting with crowding were allocated into two groups; one group received the broad Damon archwires while the other received standard 3M OrthoForm III Ovoid archwires. All participants were treated with conventional brackets using similar archwire sequences (0.014, 0.018, 0.016 × 0.022/0.016 × 0.025, 0.019 × 0.025 NiTi/CuNiTi archwires). Digital casts were obtained from alginate impressions before treatment (T0) and six weeks after inserting 0.019 × 0.025 NiTi archwires (T1). Pretreatment (T0) and post-alignment (T1) lateral cephalograms were obtained for each patient. The primary outcomes were the changes in the transverse arch dimensions and incisor inclination. The secondary outcomes were the horizontal and vertical linear changes in incisor position. RESULTS: Complete data were collected for 47 patients. There was a significant increase in arch width during treatment within each group, except for upper inter-molar width in 3M group (P = 0.071). Damon wire induced a statistically significant increase in maxillary inter-second premolar width (P = 0.042), and mandibular inter-first premolar (P = 0.043), inter-second premolar (P = 0.008) and inter-molar widths (P = 0.033) compared to 3M group. The increase in incisor proclination and the linear change in incisor position were significant within each group, with less mandibular incisor proclination (P = 0.004) and horizontal advancement (P = 0.038) in the Damon group. CONCLUSIONS: Damon archwires created a comparatively greater increase in the maxillary inter-second premolar width and the mandibular inter-first premolar, inter-second premolar, and inter-molar widths, and less proclination and horizontal advancement in mandibular incisors. The study provides invaluable evidence that using broad archwires with self-ligating brackets is the reason behind any greater expansion observed in this system rather than the unique mechanical and biological features exerted by the self-ligating system. CLINICAL RELEVANCE: Our results suggest that Damon archwire might be a better alternative compared to the narrower standard archwires that are usually used with conventional brackets, especially in the mandibular arch, in cases where mild to moderate crowding is planned to be resolved with a non-extraction approach. However, as arch expansion in the absence of posterior crossbites raises the question of long-term stability, the reported advantage of the use of wide wires should be interpreted with caution and should be considered in the retention phase, bearing in mind that achieving a good post-treatment occlusion is important for enhancing post-treatment stability.

Effects of socket-shield therapy on inter-implant papilla preservation between upper central and lateral incisors: A case series with 3-5 year follow-up.

OBJECTIVE: Despite significant progress within implant prosthetic therapy, preserving the papilla between two adjacent implants in the esthetic zone, particularly between central and lateral incisors, remains challenging. This case series aims to report a papilla preservation approach between adjacent upper central-lateral incisor implants using the socket-shield technique. CLINICAL CONSIDERATIONS: Six patients with natural dentition received unilateral adjacent central-lateral incisor implants with different socket shield configurations. The esthetic outcomes were clinically assessed after 3-5 years of follow-up. Post-operative papilla fill was evaluated on intraoral images compared to baseline characteristics and the contralateral papilla. Papilla height was preserved in all cases, with minimal alterations observed. CONCLUSIONS: Within the limitations of the present case series, the socket-shield technique demonstrated favorable outcomes in preserving the papilla between adjacent upper central-lateral incisor implants in the midterm follow-up. Clinical studies are warranted to validate these results. CLINICAL SIGNIFICANCE: The socket-shield technique seems promising in preserving the inter-implant papilla between adjacent central-lateral incisor implants.

Molar incisor hypomineralisation: Teaching and assessment across the undergraduate dental curricula in the UK.

BACKGROUND: No consensus exists on how molar incisor hypomineralisation (MIH) should be covered by the undergraduate dental curricula. AIM: To assess the current teaching and assessment of MIH in the UK. DESIGN: A piloted questionnaire regarding the teaching and assessment of MIH was disseminated to paediatric, restorative and orthodontic teaching leads in each UK dental school (n = 16). Data were analysed using descriptive statistics, chi-squared and Kruskal-Wallis tests. RESULTS: Response rates from paediatric, restorative and orthodontic teams were 75% (n = 12), 44% (n = 7) and 54% (n = 8), respectively. Prevention of caries, preformed metal crowns, anterior resin composites and vital bleaching were taught significantly more by paediatric teams (p = .006). Quality of life and resin infiltration were absent from restorative teaching. Orthodontic teaching focussed on the timing of first permanent molar extractions. Paediatric teams were mainly responsible for assessment. Risk factors, differential diagnoses for MIH and defining clinical features were more likely to be assessed by paediatric teams than by others (p = .006). All specialities reported that students were prepared to manage MIH. CONCLUSION: Molar incisor hypomineralisation is primarily taught and assessed by paediatric teams. No evidence of multidisciplinary or transitional teaching/assessment existed between specialities. Developing robust guidance regarding MIH learning in the UK undergraduate curricula may help improve consistency.

Knowledge and management of molar-incisor hypomineralisation amongst dentists in The Netherlands.

BACKGROUND: Molar-incisor hypomineralisation (MIH) is a frequently encountered dental condition in the clinical setting, and correct diagnosis can influence management outcomes. AIM: To assess the knowledge of and attitudes towards the management of MIH amongst dentists in the Netherlands. DESIGN: The study was conducted as a cross-sectional web survey. The questionnaire used included questions regarding respondent characteristics, awareness, knowledge and management of MIH and was distributed through the Royal Dutch Association for Dentistry (KNMT) to a random sample of 900 dentists. Variables were analysed using descriptive statistics, and differences between distinct groups of dentists were tested using the chi-squared test. RESULTS: Respondents consisted of 76.6% general dental practitioners, 9.1% paediatric dentists and 14.3% differentiated (specialist) dentists, with a 25.6% overall response rate. The majority knew the term MIH and its clinical characteristics, and could distinguish MIH from other enamel defects. Regarding aetiological factors, 76.6% reported a genetic component. In an asymptomatic case, 47.3% reported non-invasive treatments. In a mild symptomatic case, treatments from non-invasive to invasive were reported (p < .05). In a severe symptomatic case, the majority reported invasive treatments. Two-thirds of respondents were interested in further clinical training about MIH. CONCLUSIONS: Most respondents knew the term MIH and its clinical characteristics and would like further clinical training about MIH.

Genetic polymorphisms associated with developmental defects of enamel: A systematic review.

BACKGROUND: Polymorphisms in genes related to enamel formation and mineralization may increase the risk of developmental defects of enamel (DDE). AIM: To evaluate the existing literature on genetic polymorphisms associated with DDE. DESIGN: This systematic review was registered in the PROSPERO (CRD42018115270). The literature search was performed in PubMed, Scopus, Web of Science, LILACS, BBO, Cochrane Library, and in the gray literature. Observational studies assessing the association between DDE and genetic polymorphism were included. The Newcastle-Ottawa Scale was used to assess the risk of bias. RESULTS: One thousand one hundred and forty-six articles were identified, and 28 met the inclusion criteria. Five studies presented a low risk of bias. Ninety-two genes related to enamel development, craniofacial patterning morphogenesis, immune response, and hormone transcription/reception were included. Molar-incisor hypomineralization (MIH) and/or hypomineralization of primary second molars (HPSM) were associated with 80 polymorphisms of genes responsible for enamel development, immune response, morphogenesis, and xenobiotic detoxication. A significant association was found between the different clinical manifestations of dental fluorosis (DF) with nine polymorphisms of genes responsible for enamel development, craniofacial development, hormonal transcription/reception, and oxidative stress. Hypoplasia was associated with polymorphisms located in intronic regions. CONCLUSION: MIH, HPSM, DF, and hypoplasia reported as having a complex etiology are significantly associated with genetic polymorphisms of several genes.

Evaluation of a novel, low-cost, 3D printed video laryngoscope with borescope in anesthetized Beagle dogs.

OBJECTIVE: To develop and evaluate a low-cost three-dimensional (3D)-printed video laryngoscope (VLVET) for use with a commercial borescope. STUDY DESIGN: Instrument development and pilot study. ANIMALS: A total of six adult male Beagle dogs. METHODS: The VLVET consisted of a laryngoscope handle and a Miller-type blade, and a detachable camera holder that attached to various locations along the blade. The laryngoscope and camera holder were 3D-printed using black polylactic acid filament. Dogs were premedicated with intravenous (IV) medetomidine (15 µg kg-1) and anesthesia induced with IV alfaxalone (1.5 mg kg-1). The VLVET, combined with a borescope, was used for laryngeal visualization and intubation. Performance was evaluated by comparing direct and video-assisted views in sternal recumbency. The borescope camera was sequentially positioned at 2, 4, 6, 8 and 10 cm from the blade tip (distanceLARYNX-CAM), which was placed on the epiglottis during intubation or laryngoscopy. At the 10 cm distanceLARYNX-CAM, laryngeal visualization was sequentially scored at inter-incisor gaps of 10, 8, 6, 4 and 2 cm. Laryngeal visualization scores (0-3 range, with 0 = obstructed and 3 = unobstructed views) were statistically analyzed using the Friedman's test. RESULTS: Under direct visualization, the 2 cm distanceLARYNX-CAM had a significantly lower score compared with all other distanceLARYNX-CAM (all p = 0.014) because the view was obstructed by the camera holder and borescope camera. With both direct and camera-assisted views, visualization scores were higher at inter-incisor gaps ≥ 4 cm compared with 2 cm (all p < 0.05). CONCLUSIONS AND CLINICAL RELEVANCE: During laryngoscopy and intubation, the VLVET and borescope facilitated both direct and video laryngoscopy at distanceLARYNX-CAM in Beagle dogs when inter-incisor gaps were ≥ 4 cm.

Molar incisor hypomineralisation: A survey of awareness and management strategies among Libyan dentists in Benghazi.

BACKGROUND: Molar incisor hypomineralisation (MIH) is a developmental enamel defect in the first permanent molars and frequently in the incisors. It poses a unique challenge to the dental practitioner because of its nature, clinical presentations and treatment strategies. AIM: This study assessed the perception of Libyan dentists in Benghazi regarding MIH and its management. DESIGN: Paper-based, self-administered questionnaires were distributed to dentists in Benghazi, Libya. The questionnaires investigated the awareness of MIH, knowledge of MIH aetiology, clinical challenges of MIH treatment and choices of restorative management. Descriptive statistics, chi-squared test and binary logistic regression analysis were performed at a significance level of ≤.05. RESULTS: A total of 389 questionnaires were completed and analysed, giving an overall response rate of 76% (389/511). Most participants were female (85%, 332), with an average of 6.05 (SD = 6.24) years of experience. The majority of participants (67%) recognised MIH in their practice. Statistically significant differences in the awareness of MIH and its prevalence were observed according to the type of practice (p ≤ .001) and experience of dentists (p ≤ .001). Dentists working in public dental practice were less familiar with MIH and less likely to report it. Likewise, novice dentists were less aware of MIH than more experienced colleagues. The most reported aetiological factor in MIH was genetics by 60.2% of respondents, followed by environmental contamination (47.6%) and fluorides (42.9%). Most participants (92.3%) considered MIH a clinical problem. Aesthetics and diagnosis were the most reported challenging aspects (59.4% and 44.2%, respectively). The most commonly selected restorative options were high-fluoride glass ionomer cement (43.2%) and preformed metal crowns (41.6%). CONCLUSION: The majority of participants reported awareness of the existence of MIH condition. Nevertheless, variations in estimating MIH prevalence and its proper treatment, as well as factors influencing its treatment and diagnosis, were recorded. It is recommended that the current dental curriculum is reviewed, and scientific evidence providing dental practitioners with updated information on the diagnosis and clinical management of MIH should be circulated.

A retrospective analysis of the patient journey for children with an unerupted maxillary central incisor.

BACKGROUND: Maxillary central incisors (MCI) are the third most impacted teeth. Timely multidisciplinary management is indicated as unerupted incisors can cause functional- and appearance-related distress. AIM: To assess the patient journey for children with unerupted MCI, including referral, clinical assessment, surgical management and follow-up treatment, and highlight areas for improvement, as well as identify factors impacting orthodontic treatment burden (OTB). DESIGN: A retrospective service evaluation of children aged 6-16 years who had surgical management of unerupted MCI under general anaesthetic (GA) between 2018 and 2021. RESULTS: Fifty-two children with 62 unerupted MCI were identified. Mean age at referral was 8.8 years. Most children (82.7%) had supernumerary teeth in the anterior maxilla. Mean time between listing for GA and surgery increased from 4.3 to 15.2 months following the COVID-19 lockdown. Mean age at surgery was 10.4 years. Supernumerary removal and incisor exposure and bond was the most common treatment (56.6%). Most patients required hospital orthodontic treatment post-surgery (65.4%). CONCLUSION: Most children referred were below 9 years (60.1%); these children had reduced OTB compared to those who had been referred at an older age. Stage of root development was also a significant predictor in OTB. An unexpected finding was that conical supernumeraries were found to prevent MCI eruption.

Association between molar-incisor hypomineralisation and dental anomalies.

BACKGROUND: Common etiological factors have been reported in the development of molar-incisor hypomineralisation (MIH) and dental anomalies (DA). AIM: To assess the association between MIH and DAs. DESIGN: A cross-sectional study was performed to evaluate the presence of MIH and other six DAs in a sample of 415 pretreatment records from patients aged 9-18 years. Statistical analyses were performed using the chi-squared and Fisher's exact tests, and logistic regressions. RESULTS: There was statistically significant association between the prevalence of DAs and MIH (CI: 1.43-2.43, φ-coefficient: 0.204, PR: 1.87). Higher percentage of tooth agenesis (CI: 1.37-1.68, φ-coefficient: 0.271, PR: 1.50), maxillary premolar agenesis (CI: 1.70-3.65, φ-coefficient: 0.125, PR: 2.49), mandibular second premolar agenesis (CI: 1.68-3.16, φ-coefficient: 0.172, PR: 2.30) and distoangulation of the mandibular second premolars (CI: 1.31-3.47, φ-coefficient: 0.103, PR: 2.13) was observed among children who had MIH-affected teeth. Individuals with MIH had a 2.95 times greater chance of having DAs (R2 = .153). The number of patients with DAs was higher when the first molar showed severe defects (OR = 4.47; R2 = .149). CONCLUSION: There is a weak association between MIH and DAs. Patients with severe MIH lesions have a slightly higher risk of presenting DAs.