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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Is there a rise of prevalence for Molar Incisor Hypomineralization? A meta-analysis of published data.

Since Molar Incisor Hypomineralization was first described as a pathologic entity, public perception often suggests a considerable rise in prevalence of the respective disease. Since there are still considerable doubts regarding the etiology and-accordingly-prevention of MIH and respective therapeutic approaches are difficult this question is of considerable clinical and public interest. Accordingly, a systematic literature search in accordance with the PRISMA guidelines for systematic reviews on Medline, Cochrane Database, EMBASE, LILACS, Web of Science, Google scholar, Scopus was performed to retrieve original articles reporting the prevalence of MIH as defined by the European Academy of Pediatric Dentistry (EAPD). From initially 2360 retrieved titles, 344 full texts were assessed for possible inclusion and finally 167 articles of mainly moderate to high quality and based on data of 46'613 individuals were included in the meta-analysis. All studies published before 2001 had to be excluded since it was not possible to align the findings with the EAPD classification. Studies varied considerably regarding cohort size (25 to 23'320, mean 1'235)) and age (5.6-19 y, mean 9.8 y). Over all studies, the weighted mean for the prevalence for MIH was 12.8% (95% CI 11.5%-14.1%) and no significant changes with respect to either publication year or birthyear were found. A sub-analysis of eleven studies reporting on the prevalence in different age groups, however, revealed strong evidence for an increasing prevalence between the years 1992 (3%) and 2013 (13%).Therefore, based on data from cross-sectional studies a possible rise in prevalence of MIH remains unclear. Future prospective large-scale studies under standardized examination conditions with an emphasis on examiner calibration are needed to gain better understanding in the evolution of the prevalence of MIH.

Influence of alveolar bone thickness and bucco-palatal inclination on root resorption of lateral incisors in unilateral maxillary impacted canines: a retrospective observational study.

BACKGROUND: This study aimed to investigate the potential associations between alveolar bone thickness, bucco-palatal inclination of maxillary lateral incisors, and lateral incisor root resorption in patients with unilateral maxillary impacted canines (UMICs). METHODS: A total of three hundred and five subjects (120 males, 185 females; mean age, 16.39 years; standard deviation, 4.04) with UMICs were included. Canine position and root resorption were assessed using CBCT. UMICs were divided into palatal, buccal and mid-alveolus groups (PICs, BICs and MAICs), with 117, 137 and 51 subjects, respectively. Alveolar bone thickness and bucco-palatal inclination of lateral incisors were measured using the Dolphin software. RESULTS: The prevalence of lateral incisor root resorption was significantly lower in the BICs (13.9%) than MAICs (29.4%) and PICs (29.1%). Alveolar bone thickness of the apical area was smaller in UMICs with lateral incisor root resorption than no resorption in both PICs (8.33 ± 1.64 vs 10.53 ± 2.55 mm) and BICs (8.94 ± 1.85 vs 10.76 ± 2.28 mm). Furthermore, lateral incisors on the impacted side were more buccally inclined in PICs with lateral incisor root resorption than no resorption, while in both BICs and MAICs, there was no statistical difference between lateral incisor root resorption than no resorption. Moreover, alveolar bone thickness of the apical area, rather than bucco-palatal inclination of lateral incisors, was significantly correlated with lateral incisor root resorption both in PICs and BICs. CONCLUSIONS: Lateral incisor root resorption is less common in BICs. Thinner alveolar bone thickness at the apical area of lateral incisors can be considered as a potential risk factor for lateral incisor root resorption in UMICs.

Effect of force direction and impaction angulation during dilaceration impacted central incisor traction: a finite element analysis.

BACKGROUND: The effects of traction forces at different angles on impacted central incisors(ICI)with varying inverted angles (IA) may be different. The objective of this study was to analyze the biomechanical effects of different force directions (FD) on developmentally inverted ICI with multi-angle variations and to offer insights and guidance for the treatment of inverted ICI. METHODS: Three-dimensional finite element method was employed to simulate clinical scenarios of inverted ICI traction. As such, 0.2 N of force (direction: antero-superior angles of 90°, 100°, 110°, 120°, and 130° relative to the long axis of the inverted ICI crown) was applied to the inverted ICI with inverse angles (IA) of 40°, 30°, 20°, 10° and 0°. Inverted ICI apical displacement and Von Mises stress on periodontal ligament (PDL) and alveolar bone were compared. RESULTS: IA and FD showed minimal influence on the stress distribution in the PDL, as higher stresses were concentrated in the apical region. The higher stresses in the alveolar bone are focused on the cervical and apical regions of the tooth. In particular, IA exerts a more significant impact on stress distribution in the alveolar bone than FD. The influence of IA on the apical displacement of inverted ICI is larger than that of FD. CONCLUSIONS: To promote the health of the root and periodontal tissues, it is recommended to use an angle of 100°-110° relative to the long axis of the ICI crown when dealing with a large IA (> 20°) developmentally inverted ICI. Conversely, an angle of 110°-120° can be used.