Challenges of Using Scoring Systems for the Assessment of Molar Incisor Hypomineralisation.

The dental professional is exposed to complex challenges daily, posed by molar incisor hypomineralisation (MIH). These range from understanding its etiology through to determining the most effective strategies for clinical management of the problem. Beyond any doubt, the choice of the diagnostic scoring system to be used for recording the condition is included among these challenges. To a certain degree, this is understandable since the development of specific diagnostic tools for recording the occurrence of MIH takes place parallel to the ongoing discoveries about the problem. Therefore, the aim of this chapter is to present different MIH scoring systems that have previously been proposed in the literature for detecting MIH and discuss their applications, advantages, and limitations.

Understanding the Enamel Disintegration and Posteruptive Breakdown of Demarcated Opacities on Molar Incisor Hypomineralisation.

This review aims to present scientific knowledge regarding the demarcated opacities of molar incisor hypomineralisation (MIH) and factors that clarify the occurrence of posteruptive enamel breakdown. The demarcated opacities have distinct boundaries with the adjacent nonaffected enamel and may vary in color among white, creamy, yellow, and brownish. The hypomineralised enamel is more porous and less organized than the nonaffected enamel. As a result of the reduced mineral content and higher protein content, the hypomineralised enamel shows a progressive reduction in its mechanical properties according to the opacity feature. Chemically, the protein content of MIH opacities is abnormally high, mainly composed by albumin, which is a serum protein usually not found in mature enamel. The highest protein content is seen in brown opacities, followed by yellow and white opacities, both with higher protein content than nonaffected enamel. The fact that the hypomineralised enamel is more fragile than the nonaffected enamel is supported not only by laboratorial findings but also by clinical prospective studies that observed an aggravation of MIH over time, as well as the correlation between the color of the demarcated opacities and the risk of posteruptive enamel breakdown. A better understanding about the microstructure of the hypomineralised enamel has relevant implications for the clinical approach of the condition. In the clinic, besides a comprehensive assessment of anamnesis and clinical data, it is advisable to record the color and the location of the opacities by tooth surface in order to support the treatment decisions and estimate a prognosis for MIH patients.

Re-Establishing the Esthetics of Incisors in Patients with Molar Incisor Hypomineralisation.

The awareness of molar incisor hypomineralisation (MIH) has led to its increased clinical detection, consequently drawing more attention to its associated complications. This text offers an overview of the esthetic management of anterior teeth affected by MIH, a condition characterized by enamel defects that present significant cosmetic challenges. The focus is on the clinical presentation of MIH characteristics, considering the depth of lesions and the clinical aspects, and the treatment protocols available, despite a lack of extensive scientific evidence. To the best of the current scientific knowledge, the text evaluates the potential of minimally invasive procedures, as well as the use of traditional composite resin techniques and their possible combinations, highlighting the critical role of esthetic considerations for the impacted anterior teeth. The chapter is augmented with five illustrative clinical cases that display the practical application of these treatment approaches. These examples articulate the clinical decision-making process and personalized restorative strategies, aiming to balance function with enhanced esthetic results. The described cases act as a roadmap for clinicians tackling the complexities of MIH treatment in the context of limited empirical evidence, providing insights into achieving both satisfactory and esthetically pleasing outcomes for patients suffering from this condition.

Impact of Molar Incisor Hypomineralisation on Quality of Life.

Oral health-related quality of life (OHRQoL) is a multifaceted concept that surpasses an exclusively clinical perception and includes functional, social, emotional, and environmental issues. The measure of OHRQoL represents a holistic approach for research and clinical practice. Negative impacts of oral conditions on OHRQoL in childhood can reflect on health development, especially in a life stage marked by social and cognitive maturation. Therefore, such problems can impact negatively on the daily lives of the individuals and their families. Individuals with molar incisor hypomineralisation (MIH) experience more frequent posteruptive breakdown, an elevated risk of tooth decay, filling failures, the need for recurrent dental treatment, and a higher prevalence of dental hypersensitivity. Children with severe MIH may struggle with everyday activities, such as brushing their teeth, speaking, smiling, chewing, and consuming hot or cold foods. MIH-affected incisors may exhibit opacities that can impact the aesthetics of their smiles. This condition may discourage children from smiling and can indirectly affect their parents as well. The management modalities are focused on solving functional, aesthetic, and hypersensitivity problems and to evaluate OHRQoL values before and after therapies. Therefore, this chapter aims to discuss how MIH affects the OHRQoL of children and the questionnaires that can be used to evaluate that impact.

Fluctuating arch symmetry: a comparison of two methods of assessment - applicability and efficiency.

INTRODUCTION: Symmetry is balance, some correspondence in the size, form, and arrangements of parts on opposite sides of a plane, line, or point. The opposite of this concept is asymmetry, or imbalance. OBJECTIVE: This retrospective study compared two methods for assessing arch symmetry with linear measurements based on triangles, to determine their applicability and efficiency. METHODS: Two groups were enrolled: children (n=20) and adults (n=20), and the arch symmetry was assessed from linear measurements. Method 1: the incisor-canine (INC), canine-molar (CM), and incisor-molar (INM) distances (paired t-test and Pearson correlation). Method 2: a mathematical equation between the cusps measurements of the canines and the distobuccal of the first molars leading to result 1 (t-test for one sample and bootstrapping analysis). Dental casts were digitized and analyzed using a software program. The Bland-Altman test compared the methods (α=0.05). RESULTS: The Bland-Altman test revealed concordance between the methods; however, separately the results were different: In method 1, the mandibular arch did not demonstrate correlation (children, INC r=0.33; CM r=0.45; INM r=0.51; adults, CM r=0.46; INM r=0.35), however, the maxilla revealed a strong correlation in children and a strong/moderate correlation in adults. In method 2, both arches were symmetrical (p>0.05). CONCLUSION: Method 1 may be appropriate during orthodontic treatment, and method 2 may be indicated for final treatment. These methods are useful; however, only method 1 identified the side of asymmetry. The methods can contribute to future studies in syndromic and non-syndromic patients, before and after orthognathic surgeries and orthodontic treatment, comparing results.

Root volume measurements of maxillary canines and lateral incisors in patients with unilateral maxillary canine impaction.

OBJECTIVE: This study aimed to assess root volumes of maxillary canines and adjacent lateral incisors in patients with unilateral maxillary canine impaction. METHODS: This cross-sectional study was performed on cone-beam computed tomography (CBCT) scans of 100 patients (49 females and 51 males) with unilateral maxillary canine impaction. The images were loaded in Planmeca Romexis Viewer, and root layers between the cementoenamel junction and apex were reconstructed at 600-µm intervals. At each layer, the root boundary was marked, and finally, the root volume was calculated by multiplying the layers' area by the thickness of 600 µm. The root size of canines and lateral incisors was compared between the impaction and normal eruption sides. RESULTS: Sixty-two patients showed buccal canine impaction, and 38 presented palatal impaction. The mean root volume of canines on the impaction side was significantly greater than that on the normal eruption side; either the tooth was buccally or palatally impacted (p<0.001). The lateral incisors on the side of buccally-impacted canines showed a significantly smaller root volume than that of the contralateral side (p<0.001). However, there was no significant difference in the root size of lateral incisors between the two sides in cases presenting palatal canine impaction (p=0.177). CONCLUSION: The difference in root volume of canines between the two sides can serve as an indicator of canine impaction. The reduction in the root size of the lateral incisor on the side of the buccally impacted canine may be due to root resorption created by pressure from the canine's crown.

Orthodontic movement after regenerative endodontic procedure in mature permanent tooth associated with dens invaginatus: a case report with 4-year follow-up.

BACKGROUND: Regenerative endodontic procedures (REPs) are innovative treatments aimed at restoring damaged dental structures. However, the effect of orthodontic movement on REP-treated teeth is not well understood and may have significant long-term consequences. This study aimed to evaluate the impact of orthodontic movement on a mature permanent tooth associated with dens invaginatus that has undergone a regenerative endodontic procedure (REP). CASE PRESENTATION: This report describes the case of a 13-year-old healthy male who presented with pulp necrosis and a chronic apical abscess (tooth number 2.2). Following REP according to the American Association of Endodontists' guidelines, the patient began non-extraction orthodontic treatment with fixed appliances after a 9-month healing period, which lasted 17 months in the upper arch. Subsequent follow-ups at 24, 36 and 48 months post-REP revealed an asymptomatic state with minimal cervical discoloration and diminished cold sensitivity. Radiographic analyses revealed periapical healing, mild apical remodeling on tooth 2.2, and moderate apical remodeling on other maxillary incisors. The treated tooth displayed a positive response to both REP and orthodontic treatment, yet further research is required to determine the long-term effects of orthodontics on REP-treated teeth. CONCLUSION: Orthodontic movement following REPs in mature permanent teeth is feasible and do not seem to prone teeth to orthodontic tooth resorption. Our experience indicates that a 9-month healing period allows successful orthodontic outcomes following REPs. Nonetheless, the predictability of outcomes and the ideal healing period before orthodontic movement is initiated remain to be established.

Radiographic evaluation of enamel thickness of permanent teeth: relevance and applicability.

OBJECTIVE: This descriptive observational study aimed to determine clinically relevant and applicable data of enamel thickness (ETH), considering the mesio-distal differences of anterior and posterior permanent teeth and their relationships. MATERIAL AND METHODS: The sample consisted of right-sided standardized radiographs of 34 individuals (21 females and 13 males), aged between 13 and 24 (average 16) years, with all permanent teeth intact and without crowding. Four periapical and four interproximal radiographs were obtained and digitized. ETH measurements (mesial to distal contact points at the dentin-enamel junction) were performed after correction for radiographic image magnification. The Students' t-test was applied to the differences between paired means, with the Pearson correlation to evaluate the correlation between them. RESULTS: The mesial and distal ETH increased from the anterior to the posterior teeth. Incisor ETH ranged between 0.60 and 0.84 mm. Canines, premolars, and molars were more than 1.0 mm thick, and molar enamel reached values between 1.26 and 1.44 mm. CONCLUSION: Distal ETH was significantly greater than the mesial ETH, and progressively thicker from the anterior to posterior teeth. Interproximal reduction (IPR) of the lower central and upper lateral incisors should be avoided, reduced, or performed on their distal surfaces. There is a positive and significant correlation between ETH and the mesial and distal surfaces of the teeth. Periapical radiographs and evaluation of the remaining ETH are necessary in cases of retreatment. The location and number of tooth size discrepancies should be considered in treatment planning and appropriately compensated with IPR.

Exploring access cavity through non-carious cervical lesions: Impacts on instrumentation, obturation, and fracture resistance in mandibular incisors.

AIM: To compare the effects of Cervical Access Cavity (CervAC) and Traditional Access Cavity (TradAC) on root canal preparation, root canal filling, and fracture resistance in mandibular incisors. METHODOLOGY: Twenty recently extracted and intact mandibular incisors were initially scanned using a micro-CT device. The specimens were anatomically matched to create two groups (n = 10). A wedge-shaped non-carious cervical lesion (NCCL) was created on the buccal aspect of all teeth using a double-faced segmented diamond disc. In group 1, a TradAC was prepared, whilst in group 2, access was created through the simulated NCCL using a round diamond bur 1012. After root canal preparation with Rotate instruments sizes 15/0.04, 20/0.04, and 25/0.04, the teeth were scanned again and evaluated for root canal volume and surface area, static voxels, volume of removed dental tissue, and dentine thickness. After that, the root canals were filled using the single-cone technique, teeth were restored with composite resin, and subsequently rescanned to calculate the volume of filling materials and voids. Then, the restored teeth were subjected to fracture resistance tests using a universal testing machine. Statistical comparisons between groups were performed with the Mann-Whitney test or the Student's t-test, with a statistical significance level of 5%. RESULTS: Statistical comparisons indicated no significant differences between groups in terms of root canal volume, surface area, static voxels, removed root dentine, root canal filling volume, percentage of voids, or fracture resistance load (p > .05). Conversely, teeth prepared with TradAC showed a significantly higher percentage of dental tissue removed from the crown (p = .001) and a greater volume of filling material remnants in the pulp chamber (p < .001) compared to the CervAC group. A significantly lower percentage reduction in dentine thickness was observed only on the mesial aspect of root at Level 1 in TradAC group (p = .008). CONCLUSIONS: CervAC can be considered a viable alternative approach in the presence of NCCL in mandibular incisors.

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.

Measurement of the mandibular canal and mandibular incisive canal using cone beam tomography in adults from South Brazil.

PURPOSE: To identify and measure the distance from the dental apices to the mandibular (MC) and mandibular incisive (MIC) canals, the diameter of the MC and the distances of the mental foramen (MF). METHODS: In this retrospective study, cone-beam computed tomography scans of 144 adult patients (males and females) from a dental school in South Brazil were evaluated. Cross-sections were selected on the MC and the MIC paths, perpendicular to the mandibular base, and measurements were taken from the dental apices to the mandibular cortices. The measurement and location of the mandibular and mental foramen on both sides were compared. Paired t-tests compared sides, while Student's t-tests compared sexes (P < 0.05). RESULTS: The distance from the dental apices to the upper wall of the MC was closest in the third molar and farthest in the central incisor region. In both sexes and sides, the path of the MC is in most cases lingually in the molar regions and moves to the buccal region from the second premolar. The MF emerges in the regions between the premolars or near the second premolar. CONCLUSION: The results of this study highlight the importance of evaluating specific individual characteristics of a given population.

Biomechanical impact of labiolingual diameter on endodontically treated anterior teeth with crown restoration under occlusal loading.

OBJECTIVE: To evaluate the effect of the labiolingual diameter and construction of an endodontically treated (ET) anterior tooth with crown restoration on stress distribution and biomechanical safety under occlusal loading. METHODOLOGY: Three-dimensional finite element models were generated for maxillary central incisors with all-ceramic crown restorations. The labiolingual diameters of the tooth, defined as the horizontal distance between the protrusion of the labial and lingual surfaces, were changed as follows: (D1) 6.85 mm, (D2) 6.35 mm, and (D3) 5.85 mm. The model was constructed as follows: (S0) vital pulp tooth; (S1) ET tooth; (S2) ET tooth with a 2 mm ferrule, restored with a fiber post and composite resin core; (S3) ET tooth without a ferrule, restored with a fiber post and composite resin core. A total of 12 models were developed. In total, two force loads (100 N) were applied to the crown's incisal edge and palatal surface at a 45° oblique angle to the longitudinal axis of the teeth. The Von Mises stress distribution and maximum stress of the models were analyzed. RESULTS: Regardless of the loading location, stress concentration and maximum stress (34.07~66.78MPa) in all models occurred in the labial cervical 1/3 of each root. Both labiolingual diameter and construction influenced the maximum stress of the residual tooth tissue, with the impact of the labiolingual diameter being greater. A reduction in labiolingual diameter led to increased maximum stress throughout the tooth. The ferrule reduced the maximum stress of the core of S2 models (7.15~10.69 MPa), which is lower compared with that of S3 models (19.45~43.67 MPa). CONCLUSION: The labiolingual diameter exerts a greater impact on the biomechanical characteristics of ET anterior teeth with crown restoration, surpassing the influence of the construction. The ferrule can reduce the maximum stress of the core and maintain the uniformity of stress distribution.

Integrated correlation analysis of the thickness of buccal bone and gingiva of maxillary incisors.

OBJECTIVE: This study aimed to validate the integrated correlation between the buccal bone and gingival thickness of the anterior maxilla, and to gain insight into the reference plane selection when measuring these two tissues before treatment with implants. METHODOLOGY: Cone beam computed tomography (CBCT) and model scans of 350 human subjects were registered in the coDiagnostiX software to obtain sagittal maxillary incisor sections. The buccal bone thickness was measured at the coronal (2, 4, and 6 mm apical to the cementoenamel junction [CEJ]) and apical (0, 2, and 4 mm coronal to the apex plane) regions. The buccal gingival thickness was measured at the supra-CEJ (0, 1mm coronal to the CEJ) and sub-CEJ regions (1, 2, 4, and 6 mm apical to the CEJ). Canonical correlation analysis was performed for intergroup correlation analysis and investigation of key parameters. RESULTS: The mean thicknesses of the buccal bone and gingiva at different levels were 0.64~1.88 mm and 0.66~1.37 mm, respectively. There was a strong intergroup canonical correlation between the thickness of the buccal bone and that of the gingiva (r=0.837). The thickness of the buccal bone and gingiva at 2 mm apical to the CEJ are the most important indices with the highest canonical correlation coefficient and loadings. The most and least prevalent subgroups were the thin bone and thick gingiva group (accounting for 47.6%) and the thick bone and thick gingiva group (accounting for 8.6%). CONCLUSION: Within the limitations of this retrospective study, the thickness of the buccal bone is significantly correlated with that of the buccal gingiva, and the 2 mm region apical to the CEJ is a vital plane for quantifying the thickness of these two tissues.

The efficiency of a customized distalizer with Variety SP® screws anchored on palatal miniscrews for upper molar distalization.

OBJECTIVE: To assess the effectiveness of a customized distalizer with Variety SP® screws anchored on palatal miniscrews for upper molar distalization. METHODS: Seventeen patients aged between 12.5 and 24 years underwent distalization with a customized distalizer. Lateral cephalogram and cast analysis were performed before and after distalization. Linear and angular parameters of the upper first molar, first premolar, and central incisor were assessed. RESULTS: Distalization with the force passing near the center of resistance (CRes) of the upper first molars resulted in distal movement, with minimal distal tipping (2.8 ±â€Š0.45°, p< 0.05). However, distalization passing occlusal to the CRes led to greater distal tipping (13.6 ±â€Š1.63°, p< 0.05). Statistically significant spontaneous distal tipping and distal movement of the upper first premolars occurred, with a mean of 6.2 ±â€Š1.24° (p< 0.05) and 0.68 ±â€Š0.34 mm (p< 0.05), respectively. The positional change of the upper central incisors presented a mean of -0.23 ±â€Š0.1 mm (p> 0.05) and 2.65 ±â€Š1.1° (p< 0.05). Upper first molar intrusion was statistically significant, with a mean of 0.88 ±â€Š0.2 mm (p< 0.05). Upper right and left first molars rotation towards palatal midline presented mean of 4.1 ±â€Š0.19° (p< 0.05) and 3.4  ±â€Š0.1° (p< 0.05), respectively. Additionally, the distance between upper right and left first molars increased significantly, with a mean of 2.54 ±â€Š0.01 mm (p< 0.05). CONCLUSION: The study successfully demonstrated the efficiency of molar distalization without anchorage loss using a customized distalizer anchored on palatal miniscrews.

Ultrasonic activation of adhesive systems increases bond strength and intratubular penetration of resin cement in root dentin subjected to radiation therapy.

OBJECTIVE: This study aimed to evaluate the effect of ultrasonic activation of etch-and-rinse and self-etch adhesive systems on the bond strength of resin cement to irradiated root dentin. MATERIALS AND METHODS: Eighty human maxillary anterior teeth were distributed into 8 groups (n = 10), according to the type of adhesive system used (etch-and-rinse and self-etch), the ultrasonic activation of the adhesive systems, and the dentin condition (irradiated or non-irradiated - 70 Gy). Endodontic treatment was performed followed by fiberglass post-space preparation. After fiberglass posts' luting, the roots were transversely sectioned on dentin discs and submitted to the push-out bond strength test (0.5 mm/min). The fractured specimens were analyzed under a stereomicroscope and Scanning Electron Microscope (SEM) for failure mode classification. One of the dentin discs was analyzed under SEM to evaluate the characteristics of the adhesive interface. RESULTS: Irradiated specimens had lower bond strength than non-irradiated specimens (P < 0.0001). Ultrasonic activation of both adhesive systems increased the bond strength of the resin cement to irradiated dentin (P < 0.0001). Radiotherapy significantly affected the failure mode in the middle (P = 0.024) and apical thirds (P = 0.032) (adhesive failure). CONCLUSION: Non-irradiated specimens had a more homogeneous adhesive interface. When ultrasonically activated, both adhesive systems showed a greater number of resinous tags, regardless of the dentin condition. CLINICAL RELEVANCE: Ultrasonic activation of adhesive systems is a feasible strategy to enhance fiberglass posts retention in oncological patients.

Analysis of morphology and symmetry of the root canal system of incisors, premolars and mandibular molars using CBCT.

Knowledge of root canal internal anatomy and its variations is important forproper endodontic treatment. It is therefore necessary to investigate morphological aspects among different dental groups in the same patient to define the best protocol for the case. AIM: To evaluate the morphology and symmetry of homologous incisors, premolars and mandibular molars using cone beam computed tomography (CBCT). MATERIALS AND METHOD: Descriptive statistical analysis was performed for the frequency of categorical variables, and a chi-square test or Fisher 's exact test was used to test whether gender and side were associated with number of roots, number of canals, and Vertucci's classification. Forty-five CBCT scans were evaluated, and 444 mandibular teeth were analyzed. The number of roots, number of canals, classification of the canals in each root according to Vertucci and presence of a symmetrical relationship between pairs of posterior teeth were analyzed. RESULTS: The resuls showed that 74% of mandibular central incisors had type I root canal, 26% of mandibular lateral incisors had type I and, with a significant difference in the number of canals between males and females (p < 0.05). In mandibular first premolars, 70.5% had type I; and in mandibular second premolars, 98.5% had type I. Mandibular first molars had two roots in 98% of the cases. Second mandibular molars had two roots in 92.5% of the cases, one root in 6%, and three roots in 1.5%. Symmetry between central incisors was higher in females than in males. CONCLUSIÓN: Teeth of the same group can have different morphologies in the same patient.

0 conhecimento da anatomia interna e suas variagoes anatómicas é fator importante para o adequado tratamento endodóntico. Portanto, é necessário investigar esses aspectos morfológicos entre diferentes grupos dentários de um mesmo paciente para definir o melhor protocolo para o caso. OBJETIVO: Avaliar a morfologia e simetria de incisivos, pré-molares e molares inferiores homólogos por meio de tomografia computadorizada de feixe cónico (TCFC). MATERIAIS E MÉTODO: Foi realizada análise estatística descri-tiva para a frequéncia das variáveis categóricas e foi utilizado o teste do qui-quadrado ou teste exato de Fisher para testar a relagao entre sexo e lado em comparagao com número de raízes, número de canais e classificagao de Vertucci. Quarenta e cinco TCFC foram avaliadas e 444 dentes inferiores foram analisados. Foram considerados: o número de raízes, o número de canais, o tipo dos canais acordo com a classificagao de Vertucci e a presenga de relagao simétrica entre pares de dentes posteriores. RESULTADOS: Os resultados mostraram que 74% dos incisivos centrais inferiores tinham um canal radicular tipo 1 e 26% tinham dois canais; 73% dos incisivos laterais inferiores, 26%oeram do tipo I, tinham um canal e 27% tinham dois canais, com diferenga significativa no número de canais entre os grupos masculino e feminino (p < 0,05). Nos primeiros pré-molares inferiores, tipo I, um canal foi detectado em 70,5% e dois canais em 29,5%; nos segundos pré-molares inferiores, tipo I, um único canal foi detectado em 98,5%. O primeiro molar inferior foi observado com duas raízes em 98% e tres raízes em 2%o. O segundo molar inferior tinha duas raízes em 92,5% dos casos, uma raiz em 6% e tres raízes em 1,5%. A simetria foi maior nas mulheres em comparagao aos homens nos incisivos centrais. CONCLUSÃO: Pode-se concluir que dentes de um mesmo grupo podem apresentar morfologias diferentes no mesmo paciente.

Traumatic dental injuries and molar incisor hypomineralization: a cross-sectional study of schoolchildren from southern Brazil.

PURPOSE: To describe the prevalence and the variables associated with TDIs in schoolchildren aged 8 to 14 years in Estância Velha city in southern Brazil, placing emphasis on molar incisor hypomineralization. METHODS: Students enrolled in public schools of a medium-sized city in the southern Brazil were selected using cluster random sampling. Clinical examinations assessed molar incisor hypomineralization-MIH (European Academy of Pediatric Dentistry criteria), dental caries (DMFT index), and TDIs (O'Brien's criteria). Socioeconomic and demographic variables were assessed using a standardized questionnaire. Prevalence ratios were estimated using Poisson regression (p < 0.05). RESULTS: 513 students (54.8% female), with a mean age of 11.6 (± 1.9) years, participated in the study. The prevalence of TDIs was 11.3%, with enamel fracture representing 90.4%. The high prevalence of traumatic dental injuries was associated with MIH (PR: 2.22 CI: 1.27; 3.87; p < 0.01) and overjet > 3 mm (PR: 2.03 CI 1.19; 3.45; p < 0.01). CONCLUSION: The sample of schoolchildren from southern Brazil had a low prevalence of traumatic dental injuries. Molar incisor hypomineralization and increased overjet were associated with the higher prevalence of traumatic dental injuries.

Root Regeneration with Photobiomodulation of an Upper Lateral Incisor Associated with Root Resorption Due to an Impacted Maxillary Canine: A Case Report.

Objective: To present a case report of maxillary lateral incisor root regeneration after severe root resorption, treated with photobiomodulation (PBM). Background: Impacted maxillary canines often come with the risk of maxillary lateral incisor root resorption, which is widely recognized as the predominant adverse effect in these situations. This progressive process of root resorption is currently irreversible, with no known way to reverse it. Materials and methods: A male patient was 14 years old. Radiographically it was observed that canine 23 is impacting against the root of 22 producing signs of root resorption and having a less than 1:1 crown-to-root ratio with mobility grade 1. From the beginning of the treatment, PBM-assisted orthodontics was proposed. To address the patient's dental concerns, the treatment plan outlined the extraction of the deciduous upper left canine tooth leaving the lateral as long as possible in the mouth. During each appointment, PBM was applied with a diode laser. The wavelength was 810 nm, Ap = 0.2 W, 4.4 J, 22 sec every 21 days, 13 applications in total (57.2J), with a 400 µm inactive surgical tip, in a scanning movement, 1 mm from the mucosa while moving following the vestibular surface of the upper left lateral and canine roots. Results: After 12 months, the 22 had root neoformation and complete closure of the apex with vitality. Conclusions: PBM with an 810 nm diode laser in this clinical case promoted root regeneration of an upper lateral incisor, with severe root resorption, owing to an impacted maxillary canine while still vital.

Dental implant and abutment in PEEK: stress assessment in single crown retainers on anterior region.

OBJECTIVE: Stress distribution assessment by finite elements analysis in poly(etheretherketone) (PEEK) implant and abutment as retainers of single crowns in the anterior region. MATERIALS AND METHODS: Five 3D models were created, varying implant/abutment manufacturing materials: titanium (Ti), zirconia (Zr), pure PEEK (PEEKp), carbon fiber-reinforced PEEK (PEEKc), glass fiber-reinforced PEEK (PEEKg). A 50 N load was applied 30o off-axis at the incisal edge of the upper central incisor. The Von Mises stress (σvM) was evaluated on abutment, implant/screw, and minimum principal stress (σmin) and maximum shear stress (τmax) for cortical and cancellous bone. RESULTS: The abutment σvM lowest stress was observed in PEEKp group, being 70% lower than Ti and 74% than Zr. On the implant, PEEKp reduced 68% compared to Ti and a 71% to Zr. In the abutment screws, an increase of at least 33% was found in PEEKc compared to Ti, and of at least 81% to Zr. For cortical bone, the highest τmax values were in the PEEKp group, and a slight increase in stress was observed compared to all PEEK groups with Ti and Zr. For σmin, the highest stress was found in the PEEKc. Stress increased at least 7% in cancellous bone for all PEEK groups. CONCLUSION: Abutments and implants made by PEEKc concentrate less σvM stress, transmitting greater stress to the cortical and medullary bone. CLINICAL RELEVANCE: The best stress distribution in PEEKc components may contribute to decreased stress shielding; in vitro and in vivo research is recommended to investigate this.

Accuracy of Invisalign® aligners in adult patients: a retrospective study of angular tooth movements.

OBJECTIVE: This retrospective study aimed to assess the predictability of Invisalign® aligners regarding rotational, mesio-distal and buccal-lingual tip movements. METHODS: Two materials were included in the analysis - EX30, used until 2013; and SmartTrack, in current use. The study comprised 56 adult patients treated with Invisalign Comprehensive. Data sample were assessed on three sets of digital models; model 1 - initial, model 2 - predicted, and model 3 - achieved. Sixty reference points were marked in each dental arch, and two reference planes assisted the superimposition. The degree of rotation, mesio-distal and buccal-lingual tip was obtained via trigonometric calculations, through a previously published validated method. The accuracy of outcomes was compared according to the types of tooth movement and teeth groups,and the influence of predetermined variables on movement accuracy was also investigated. RESULTS: Rotation and mesio-distal tip did not present any significant difference when comparing EX30 and SmartTrack groups. Only buccal-lingual tip presented a significant difference, incisor and canine groups treated with EX30 aligners presented an increase in accuracy (p= 0.007 and p = 0.007, respectively). For each additional degree planned for rotation movements, there was an increase of 0.35° in the discrepancy, and an increase of 0.40° and 0.41° for mesio-distal and buccal-lingual tip, respectively. EX30 and SmartTrack discrepancies were compared by multilevel linear regression. CONCLUSION: EX30 aligners reached higher accuracy for buccal-lingual tip in anterior teeth. However, for rotation and mesio-distal tip, SmartTrack and EX30 are similarly accurate. The total amount of planned movement has a significant impact on accuracy rates, with a decrease in accuracy for every additional degree.