Relación del plano oclusal con la altura del ángulo goníaco y proyección del mentón / Relation of the occlusal plane with the height of the gonial angle and projection of the chin

Introducción: hemos observado en nuestra práctica ortodóncica una gran cantidad de pacientes con plano oclusal inclinado, con un ángulo goníaco alto y postero-rotación mandibular. Todo parece indicar que el plano oclusal juega un papel muy importante en el desarrollo de las maloclusiones. Objetivo: mostrar en el presente caso clínico de un niño, si existe una correlación entre la inclinación del plano oclusal, la altura del ángulo goníaco, la longitud de la rama mandibular y la proyección del mentón antes y después, al corregirlo y hacerlo más horizontal con tratamiento ortodóncico. Caso clínico: paciente masculino de 11 años de edad, hiperdivergente, clase II esquelética severa, perfil convexo, apiñamiento dental superior e inferior, clase II molar, incompetencia labial severa, mordida profunda, overjet aumentado, mentón retrusivo, cervicales rectificadas y anterorotación de cabeza. El tratamiento de ortodoncia se realizó con brackets Roth slot 22 y extracciones de primeros premolares superiores e inferiores y primeros molares superiores (siendo reemplazados por los terceros molares superiores), curvas inversas, cierre de espacios con pérdida de anclaje y ajuste oclusal. Resultados: al finalizar el tratamiento, se logró mejorar la estética facial, un ángulo goníaco más desarrollado con mayor crecimiento vertical, mayor proyección del mentón, un plano oclusal más horizontal, un adecuado overbite y overjet, clase I molar y canina, antero-rotación mandibular, buena intercuspidación, oclusión funcional y excelente estabilidad oclusal sin retención, mejoría en lordosis cervical y posición de la cabeza. Conclusiones: la corrección de un plano oclusal inclinado en niños y adolescentes hiperdivergentes, puede mejorar de manera importante el vector de crecimiento, ayudar a un mayor desarrollo en la altura del ángulo goníaco y longitud de la rama mandibular, proyección del mentón al corregirlo y hacer el plano oclusal más horizontal con la mecánica ortodóntica de curvas inversas; por lo tanto, en el presente caso clínico: sí existe una correlación muy importante entre la inclinación del plano oclusal, la altura del ángulo goníaco y la proyección del mentón antes y después del tratamiento ortodóncico (AU)

Introduction: we have observed in our orthodontic practice a large number of patients with inclined occlusal plane, with a high goniac angle and posterior mandibular rotation. Everything seems to indicate that the occlusal plane plays a very important role in the development of malocclusions. Objective: to show in the present clinical case of a child, if there is a correlation between the inclination of the occlusal plane, the height of the goniac angle, the length of the mandibular branch and the projection of the chin before and after, when correcting it and making it more horizontal with orthodontic treatment. Case report: an 11 year old male patient, hyperdivergent, severe skeletal class II, convex profile, upper and lower dental crowding, molar class II, severe labial incompetence, deep bite, increased overjet, retrusive chin, rectified cervicals, and anterorotation of the head. Orthodontic treatment was performed with Roth slot 22 brackets and extractions of upper and lower first premolars and upper first molars (being replaced by upper third molars), inverse curve, space closure with loss of anchorage and occlusal adjustment. Results: at the end of the treatment, it was possible to improve facial aesthetics, a more developed gonial angle with greater vertical growth, greater chin projection, a more horizontal occlusal plane, an adequate overbite and overjet, molar and canine class I, mandibular anterorotation, good intercuspidation, functional occlusion and excellent occlusal stability without retention, improvement in cervical lordosis and head position. Conclusions: the correction of an inclined occlusal plane in hyperdivergent children and adolescents can significantly improve the growth vector, help further development in the height of the gonial angle and length of the mandibular ramus, chin protection when correcting it and making the most horizontal occlusal plane with the orthodontic mechanics of inverse curves; therefore, in the present clinical case: there is a very important correlations between the inclination of the occlusal plane, the height of the gonial angle and chin projection before and after orthodontic treatment (AU)

Four-year follow-up study of onlay and occlusal veneer restorations on posterior teeth / 北京大学学报(医学版)

Objective:To investigate the survival rate and clinical failure reasons of onlay and occlusal veneer restorations retrospectively,and to put forward valuable suggestions for the selection of clinical in-dications.Methods:A total of 102 patients and 124 teeth treated by one of the authors from 2016 to 2019 were subjected to CAD/CAM lithium silicate reinforced glass-ceramic onlay or veneer restorations of premolars and molars,including 43 teeth with pulp vitality,81 endodontic treated teeth,and occlusal thickness of restoration was 1.5 mm.After four years of restoration,retrospective surveys were conducted to record the survival rate of restorations,the causes of restoration failure,and patient satisfaction rates,and the survival rate of restorations between vital teeth and endodontic treated teeth and among restored teeth was statistically analyzed by Chi-square test.Results:The survival rates of restorations on vital teeth and endodontic treated teeth were 95.5％and 90.0％,respectively,the average survival rate was 90.2％.The survival rates of vital teeth were higher than those of endodontic treated teeth without statis-tical difference.There was also no statistically significant difference among the tooth locations.The cau-ses of failure included the cracking of the restoration,the loss of the restoration,the fracture of the abut-ment teeth,secondary caries below the adjacent contact point,and food impaction caused by the loose-ning of the adjacent contact point.The overall patient satisfaction rate was 91.5％.Conclusion:The 4-year survival rate of glass-ceramic onlays and occlusal veneers is lower than that of the full crown restora-tion,and there are more complications than that of the single-crown restorations.The design of the resto-ration should be carefully selected based on the vitality of the abutment tooth and the remaining amount of tooth tissue.When there is too little tooth structure left,a post and crown should be selected for restora-tion.Adequate strength and thickness of the restoration should be ensured to prevent food impaction.Due to the small amount of abutment tooth preparation,it has the advantages of less stimulation of the pulp and periodontal tissue,and can be recommended as a trial restoration.

Biomechanical difference between resin ceramic crown and zirconia all-ceramic crown implant restorations in three occlusal relationships / 中国组织工程研究

BACKGROUND:In implant restoration in the aesthetic area,zirconium dioxide is gradually becoming the most commonly used upper restorative material and has achieved better clinical results.Resin-ceramic composite,a new type of dental restorative material,begins to try to be used as an upper restorative material in implant restoration,but there is less research on the application of this material in implant restoration. OBJECTIVE:To compare the biomechanical differences between resin ceramic crowns and zirconia all-ceramic crown implant restorations in three occlusal relationships for restoring maxillary central incisors. METHODS:The cone-beam CT image data of a patient with single-crown implant restoration of maxillary central incisor were selected,and the maxillary bone model was extracted by using Mimics 21.0 software,and the model was imported into Solidworks 2020 software.The crown,adhesive,abutment,central screw,and implant were modeled,and the model of single-crown implant restoration of maxillary central incisor was assembled.After giving the model material property parameters(resin-ceramic composite and zirconia for the upper restoration materials)in ANSYS Workbench 2021 R1 software,three occlusal relationships(edge-to-edge occlusion,normal overjet and deep overbite)were simulated and loaded to analyze the stress distribution of the resin-ceramic crown and zirconia all-ceramic crown implant restoration models. RESULTS AND CONCLUSION:(1)The stress concentration areas in the implant restoration models of the resin-ceramic crown group and the zirconia all-ceramic crown group in different occlusal relationships were distributed in the upper restoration loading point,the abutment-implant connection,the implant neck and the surrounding bone tissue.As the occlusal relationship changed from the edge-to-edge to normal and deep overbite,the peak equivalent forces of the restorative abutment,central screw,implant,and bone tissue in both the resin-ceramic and zirconia all-ceramic crown groups gradually decreased.The highest peak equivalent forces were observed for the upper restorations in deep overbite.The zirconia all-ceramic crown group had the highest peak equivalent force in the adhesive layer in the edge-to-edge relationship,and the resin-ceramic crown group had the highest peak equivalent force in the adhesive layer in the deep overbite.(2)In the edge-to-edge occlusion,the peak equivalent force of the adhesive layer and central screw in the resin-ceramic crown group was slightly smaller than that in the zirconia all-ceramic crown group,and there was no significant difference between the two groups in the peak equivalent force at the upper restoration,restoration abutment,implant,and bone tissue.The peak stresses in the upper restoration,adhesive layer,and central screw of the resin-ceramic crown group were slightly less than those of the zirconia all-ceramic crown group at normal fit,and there were no significant differences between the two groups in the peak equivalent forces at the restoration abutment,implant,and bone tissue.In deep overbite,the peak adhesive,abutment,and central screw stresses were greater in the resin-ceramic crown group than in the zirconia all-ceramic crown group,with no significant differences in the upper restorations,implants,or bone tissue.(3)The results showed that the upper restorative material had no significant effect on the stress distribution of the implant and bone tissue,and had some effects on the stress distribution of the upper restoration,adhesive,restoration abutment,and central screw,but the difference was not significant.The occlusal relationship has a significant influence on the stress distribution in all structures and bone tissue of the implant restoration.The resin-ceramic crowns have a buffering effect on the stresses in the case of edge-to-edge and normal occlusion.

Finite element analysis of the effect of bone on occlusal adjustment of right upper first molar implants / 中国组织工程研究

BACKGROUND:Bone tissue remodeling is closely related to stress loading.Currently,there are few studies or guidelines on the relationship between bone and occlusal adjustment of implant prostheses and there is also a lack of scientific evidence. OBJECTIVE:To investigate the effects of different implant occlusal gaps on stress distribution,stress peak and displacement at the implant-bone interface under Ⅰ-Ⅳ bone conditions by a finite element method. METHODS:After scanning the equal-scale tooth model with an optical scanner,equal-scale models of the upper right first molar Straumann 4.8×8 mm BL RC implant and its related components was constructed using Solidworks 2022.Then,using Mimics,Geomagic,and Solidworks software,the maxillary and mandibular bone models of class Ⅰ-Ⅳ bones were established based on the bone classification proposed by ZARB and LEKHOLM in the literature,and the NORTON and TRISI bone density classification method.The models were assembled with the occlusal gaps of 0,20,40,60,80,and 100 μm for the restorations,and an additional set of homogeneous models without density ratio settings was constructed for comparison.After the above models were imported into Hypermesh for meshing,the material assignment,boundary constraints and parameter setting were performed for the finite element analysis.Finally,250 N was used as the loading force to simulate the maxillary and mandibular stress conditions.Stress distribution,peak stress and displacement of the implant-bone interface in each group of models were analyzed and compared. RESULTS AND CONCLUSION:Under the same loading conditions,the stresses in the implant restorations were evenly distributed with the occlusal contact points.When the occlusal gap reached 80 and 100 μm,stress interruptions occurred in the implant crowns under class Ⅰ bone and class Ⅱ,Ⅲ and Ⅳ bones,respectively.The displacement of the implant-bone interface was mainly concentrated in the cortical bone region around the implant and transmitted down the long axis of the implant to the cancellous bone region at the bottom.With the changes of class Ⅰ-Ⅳ jaw bones,the displacement and Von Mises stress in the cortical bone region increased in all groups,and were greater than those in the cancellous bone region.The Von Mises stress in the cancellous bone region was similar to that in the cortical bone region except that it showed a downward trend from class Ⅱ bone.However,when the occlusal gap increased,the stress and displacement peak values in the cortical bone and the cancellous bone showed a decreasing trend.The stress of the implant-bone interface was between 20 MPa and 60 MPa when the occlusal gap was 0-40 μm for class Ⅱ-Ⅳ bones and 60 μm for class Ⅳ bone,and the stress of the other groups was less than 20 MPa.The Von Mises stress was mainly concentrated in the neck of the implant,and the peak value of von Mises stress in class Ⅱ-Ⅳ bones with the occlusal gap of 20 μm was higher than that(144.10 MPa)in class Ⅰ bone with the occlusal gap of 0 μm.In the homogeneous model with different elastic moduli,the distribution of stress and displacement was more uniform than that in the heterogeneous model and the occlusal space should increase with the decrease of jaw bone density in clinical practice.To conclude,from the perspective of biomechanics,the alveolar bone should be taken into account in the occlusal adjustment of implant denture.An occlusal gap of 20-40 μm between a single dental implant and a natural tooth in the opposite jaw is a relatively suitable solution for occlusal adjustment under different bone conditions.However,due to the particularity of finite element analysis method,it needs to be further studied in combination with clinical practice.

Efficiency of mixed and rigid occlusal stabilization splints: Randomized clinical trial

Abstract Occlusal stabilization splints are the most common treatment for controlling the deleterious effects of sleep bruxism. This study aimed to evaluate the effectiveness of a low-cost, mixed occlusal splint (MOS) compared to that of a rigid splint. A randomized clinical trial was performed on 43 adults of both sexes with possible sleep bruxism and satisfactory dental conditions. They were divided into rigid occlusal splint (ROS) (n = 23) and MOS (n = 20) groups. Masticatory muscle and temporomandibular joint (TMJ) pain intensity (visual analog scale), quality of life (WHOQOL-BREF), indentations in the oral mucosa, anxiety, and depression (HADS), number of days of splint use, and splint wear were evaluated. All variables were evaluated at baseline (T0), 6 months (T6), and 12 months (T12) after splint installation (T0), and splint wear was evaluated at T6 and T12. Student's t-test, Mann-Whitney U test, non-parametric Friedman's analysis of variance for paired samples and pairwise multiple comparisons, Pearson's chi-square test, two-proportion z-test, non-parametric McNemar's and Cochran's Q, and Wilcoxon tests were used (p < 0.05). In both groups, there was a decrease in TMJ pain and pain intensity over time and improvements in the quality of life scores. At T6, there was a higher rate of splint wear in the MOS group than in the ROS group (p = 0.023). The MOS showed a higher rate of wear than the rigid splint but had similar results for the other variables. Therefore, the use of a mixed splint appears to be effective in controlling the signs and symptoms of sleep bruxism.

The impact of occlusal forces on the longevity of restorations

The longevity of dental restorations like fillings, crowns, and bridges is critically influenced by occlusal forces exerted during biting and chewing. These forces vary among individuals based on diet, masticatory habits, and the structural soundness of the dental arch and can range from 11 to over 450 Newtons, depending on circumstances. The choice of restorative material is important for withstanding these forces. While amalgam is durable, modern dentistry has shifted towards aesthetic restoratives such as composite resins and ceramics. However, these materials respond differently to occlusal forces. Ceramics might fracture under excess load, whereas composite resins resist wear but can degrade over time due to other factors. Precision in restoration is crucial to preventing undue occlusal forces that might lead to restoration failure. Tools like T-scan assist in this precision. The manner and distribution of occlusal forces, along with the health of the periodontal ligament, are critical for restoration durability. Bruxism, a parafunctional habit, can significantly impact restorations, necessitating protective measures like occlusal splints and patient education. The interplay of occlusal forces and the chosen restorative material greatly affects the success and lifespan of dental restorations.

Comportamiento Mecánico de un Premolar Humano Sano Sometido a Fuerzas Funcionales y Disfuncionales en un MEF / Mechanical Behavior of a Healthy Human Premolar Subjected to Functional and Dysfunctional Forces in a FEM

El propósito de este estudio fue analizar el comportamiento mecánico de la estructura dental sana de un primer premolar inferior humano sometido a fuerzas funcionales y disfuncionales en diferentes direcciones. Se buscó comprender, bajo las variables contempladas, las zonas de concentración de esfuerzos que conllevan al daño estructural de sus constituyentes y tejidos adyacentes. Se realizó el modelo 3D de la reconstrucción de un archivo TAC de un primer premolar inferior, que incluyó esmalte, dentina, ligamento periodontal y hueso alveolar considerando tres variables: dirección, magnitud y área de la fuerza aplicada. La dirección fue dirigida en tres vectores (vertical, tangencial y horizontal) bajo cuatro magnitudes, una funcional de 35 N y tres disfuncionales de 170, 310 y 445 N, aplicadas sobre un área de la cara oclusal y/o vestibular del premolar que involucró tres contactos estabilizadores (A, B y C) y dos paradores de cierre. Los resultados obtenidos explican el fenómeno de combinar tres vectores, cuatro magnitudes y un área de aplicación de la fuerza, donde los valores de esfuerzo efectivo equivalente Von Mises muestran valores máximos a partir de los 60 MPa. Los valores de tensión máximos se localizan, bajo la carga horizontal a 170 N y en el proceso masticatorio en la zona cervical, cuando la fuerza pasa del 60 %. Sobre la base de los hallazgos de este estudio, se puede concluir que la reacción de los tejidos a fuerzas funcionales y disfuncionales varía de acuerdo con la magnitud, dirección y área de aplicación de la fuerza. Los valores de tensión resultan ser más altos bajo la aplicación de fuerzas disfuncionales tanto en magnitud como en dirección, produciendo esfuerzos tensiles significativos para la estructura dental y periodontal cervical, mientras que, bajo las cargas funcionales aplicadas en cualquier dirección, no se generan esfuerzos lesivos. Esto supone el reconocimiento del poder de detrimento estructural del diente y periodonto frente al bruxismo céntrico y excéntrico.

SUMMARY: The purpose of this study was to analyze the mechanical behavior of the healthy dental structure of a human mandibular first premolar subjected to functional and dysfunctional forces in different directions. It was sought to understand, under the contemplated variables, the areas of stress concentration that lead to structural damage of its constituents and adjacent tissues. The 3D model of the reconstruction of a CT file of a lower first premolar was made, which included enamel, dentin, periodontal ligament and alveolar bone considering three variables: direction, magnitude and area of the applied force. The direction was directed in three vectors (vertical, tangential and horizontal) under four magnitudes, one functional of 35 N and three dysfunctional of 170, 310 and 445 N, applied to an area of the occlusal and/or buccal face of the premolar that involved three stabilizing contacts (A, B and C) and two closing stops. The results obtained explain the phenomenon of combining three vectors, four magnitudes and an area of force application, where the values of effective equivalent Von Mises stress show maximum values from 60 MPa. The maximum tension values are located under the horizontal load at 170 N and in the masticatory process in the cervical area, when the force exceeds 60%. Based on the findings of this study, it can be concluded that the reaction of tissues to functional and dysfunctional forces varies according to the magnitude, direction, and area of application of the force. The stress values turn out to be higher under the application of dysfunctional forces both in magnitude and in direction, producing significant tensile stresses for the dental and cervical periodontal structure, while under functional loads applied in any direction, no damaging stresses are generated. This supposes the recognition of the power of structural detriment of the tooth and periodontium against centric and eccentric bruxism.

Relationship between the occlusal plane and three different levels of ala-tragus line in a sample of sudanese adults / Relación entre el plano oclusal y tres niveles diferentes de la línea ala-trago en una muestra de adultos sudaneses

Aim: Correct orientation of the occlusal plane plays a vital role in achieving the perfect occlusal balance and function of complete dentures. This study aimed to evaluate the most reliable posterior reference point of the ala-tragus line (ATL) concerning occlusal plane (OP) in a sample of the dentate Sudanese population. Materials and Methods: A total of 150 subjects with healthy and well-aligned permanent teeth were randomly selected. Right lateral profile photographs were taken with subjects having a fox plane placed intra-orally, contacting the occlusal plane. Reference points corresponding to inferior, middle, and superior borders of the tragus and inferior border of the ala of the nose were marked on photographs. The angles between the lines were measured using the Auto-CAD software program, and the most parallel relationship was determined. Descriptive statistics in terms of means and standard deviations were presented. Independent t-test and one-way ANOVA tests were used to compare as appropriate. A p-value < 0.05 was considered significant. Results: The mean angle formed by the OP and ATL was 8.5±3.69º for the superior level, 4.68±3.13º for the middle line, and 2.89±2.57º for the inferior line. A significant difference was found between the means of the three angles (p< 0.001), while no significant difference (p> 0.05) was found between both genders regarding the measured angles. Conclusions: The line joining the inferior border of the ala of the nose with the inferior border of the tragus of the ear was the most reliable line in terms of parallelism to determine the occlusal plane orientation.

Antecedentes: La orientación correcta del plano oclusal juega un papel vital para lograr el equilibrio oclusal perfecto y la función de las prótesis completas. Este estudio tuvo como objetivo evaluar el punto de referencia posterior más confiable de la línea ala-trago (ATL) con respecto al plano oclusal (OP) en una muestra de la población dentada de Sudán. Materiales y Métodos: Se seleccionaron aleatoriamente un total de 150 sujetos con dientes permanentes sanos y bien alineados. Se tomaron fotografías de perfil lateral derecho de sujetos a los que se les colocó un plano de zorro intraoralmente, en contacto con el plano oclusal. En las fotografías se marcaron los puntos de referencia correspondientes a los bordes inferior, medio y superior del trago y al borde inferior del ala de la nariz. Los ángulos entre las líneas se midieron utilizando el programa de software Auto-CAD y se determinó la relación más paralela. Se presentaron estadísticas descriptivas en términos de medias y desviaciones estándar. Se utilizaron prueba-t independiente y prueba ANOVA unidireccional para las comparaciones, según correspondiera. Se consideró significativo un valor de p<0,05. Resultados: El ángulo medio formado por OP y ATL fue de 8,5±3,69º para el nivel superior, 4,68±3,13º para la línea media y 2,89±2,57º para la línea inferior. Se encontró una diferencia significativa entre las medias de los tres ángulos (p< 0,001), mientras que no se encontró diferencia significativa (p>0,05) entre ambos sexos con respecto a los ángulos medidos. Conclusión: La línea que une el borde inferior del ala de la nariz con el borde inferior del trago de la oreja fue la línea más confiable en términos de paralelismo para determinar la orientación del plano oclusal.

A Study of Post Insertion Problems in Removable Partial Dentures in Kashmiri Population – A Survey Based Research

The aim of this study is to collect data of various post insertion problems in removable partial dentures which were examined in the department of prosthodontics in government dental college srinagar. Around 200 patients were included in the study . The various problems that could be found in removable partial dentures include pain, discomfort, inflammatory conditions, problems in speech, loose dentures, occlusal problems, difficulty in deglutition, residual ridge resorption and altered taste perception.

Oclusión basada en evidencia: rompiendo paradigmas / Occlusion based on evidence: breaking paradigms

La odontología basada en evidencias es una metodología que busca que las decisiones clínicas diarias que toman los profesionales en estomatología se encuentren fundamentadas en la evidencia científica, en ella se integran las experiencias clínicas, las necesidades, las preferencias del paciente y la evidencia clínicamente relevante más actual analizada por pares. Estos pilares son parte del proceso en la toma de decisiones para la atención al paciente. La odontología basada en evidencias surge de las exitosas experiencias obtenidas con el desarrollo e implementación de la medicina fundamentada en pruebas, al aplicar el método científico en la evaluación, planificación y toma de decisiones de las prestaciones sanitarias, sobre todo a través de los estudios controlados. En general, toda la práctica odontológica ha tenido grandes avances basados en evidencias, con hechos verídicos comprobados, pero los conceptos fundamentales de oclusión no han tenido una mejora cimentada en el conocimiento científico, prueba de ello es que se siguen ocupando teorías y conceptos de las filosofías de oclusión en la rehabilitación de muchos pacientes, seguimos creyendo en mitos y sofismas que no han podido ser demostrados. En esta revisión, demostramos los grandes avances en los conceptos de oclusión e invitamos a todos los odontólogos a romper los paradigmas de la oclusión antigua sin evidencias científicas y a utilizar las herramientas del método científico en la práctica clínica odontológica (AU)

Evidence-based dentistry is a strategy that seeks to ensure that the daily clinical decisions made by the dental professional are based on scientific evidence. It integrates the clinical experience of the dentist, the needs and preferences of the patient, and the most current relevant clinical evidence. All three are part of the decision-making process for patient care. Evidence-based dentistry arises from the successful experiences obtained with the development and implementation of evidence-based medicine, applying the scientific method in the evaluation, planning and decision-making of health benefits, especially through controlled studies. In general, all dental practice has had great advances based on evidence, with proven true facts, but the fundamental concepts of occlusion have not had an improvement based on scientific knowledge, proof of this is that theories and concepts continue to be used. of the philosophies of occlusion in patient rehabilitation, we follow myths and sophisms that have not been demonstrated, in this review, we demonstrate the great advances in the concepts of occlusion and we know all dentists to break the paradigms of the old occlusion without scientific evidence (AU)

Fuerza de ruptura y adaptación marginal de carillas oclusales confeccionadas con CAD/CAM composite, cerámica híbrida y feldespática fijadas con distintos medios cementantes / Breaking strength and marginal adaptation of occlusal veneers made with CAD / CAM composite, hybrid ceramic and feldspathic fixed with different cementing medium

Resumen Objetivos: a) Comparar la fuerza de ruptura (FR), adaptación marginal externa (AME) y angulación intracuspídea (AI) entre carillas oclusales confeccionadas con composite, cerámica híbrida y feldespática obtenidas con sistemas CADCAM fijadas con distintos medios cementantes y b) evaluar si el medio cementante, la AME y la AI influyen en la FR. Materiales y métodos: 50 premolares conformaron 6 grupos de acuerdo a la combinación de los materiales Cp, omposite Paradigm MZ100 (P), Cerámica híbrida VitaEnamic (VE), Cerámica feldespática Vitablocks Mark II (F) con los cementos Variolink N curado dual (VN) o resina compuesta Z100 calentada (RC): Grupo 1 (n=10) P-VN, Grupo 2 (n=10) P-RC, Grupo 3 (n=10) VE-RC, Grupo 4 (n=10) VE-VN, Grupo 5 (n=5) F-VN, Grupo 6 (n=5) F-RC. Los dientes preparados y acondicionados recibieron carillas confeccionadas utilizando el Sistema Cerec 3. Luego, fueron sometidas a fuerzas compresivas en una máquina de ensayos universal, aplicando una carga con una velocidad de desplazamiento igual a 0,5 mm/ minuto hasta el cese por fractura catastrófica. Previo a realizar los ensayos se midió la AME en sus cuatro caras y la AI. Resultados: Se obtuvieron valores de mayor FR para los Grupos 1 y 2, que se diferenciaron significativamente de los otros 4 grupos (p<0,05). El medio cementante no influyó sobre la FR (p>0,05). Hubo diferencias con relación a los materiales y la AME favoreciendo al Grupo 1 (p<0,05). Conclusiones: Las carillas oclusales confeccionadas en composite con sistemas CAD-CAM (Paradigm MZ100) necesitaron mayor fuerza para provocar su ruptura y registraron menores desadaptaciones.

Abstract Aims: a)To compare the breaking strength (BS), external marginal adaptation (EMA) and intracuspid angulation (ID) between occlusal veneers made with composite, hybrid ceramic and feldspathic obtained with CAD-CAM systems fixed with different cementing medium and b) to evaluate the effect that the cement, the EMA and ID have on the BS. Materials and methods: 50 premolars formed 6 groups according to the combination of the Composite Paradigm MZ100 (P), VitaEnamic hybrid ceramic (VE), Vitablocks Mark II feldspathic ceramic (F) with the dual-cured Variolink N (VN) or Z100 Heated Composite Resin (RC): Group 1 (n10) P-VN, Group 2 (n10) P-RC, Group 3 (n10) VERC, Group 4 (n10) VE-VN, Group 5 (n5) F-VN, Group 6 (n5) F-RC. The teeth received a preparation and were conditioned, subsequently, they received occlusal veneers using the Cerec 3 System. They were then subjected to compressive forces in a Testing Machine, applying a load with a speed of movement equal to 0.5 mm/ minute until it stopped due to catastrophic fracture. Before carrying out the tests, the EAM was registered in four faces and the ID was measured. Results: Higher BS were obtained for Groups 1 and 2, which differed significantly from Groups 3,4,5 and 6 (p<0.05). The cementing medium did not influence the BS (p>0.05). There were differences in relation to the materials and the EMA favoring Group 1 (p<0.05). Conclusions: The occlusal veneers made in composite with CAD-CAM systems (Paradigm MZ100) required greater force to cause their rupture and registered less misadaptations.

Comportamiento de la maloclusión funcional e interferencias oclusales en niños con dentición mixta

Introducción: las interferencias oclusales no controladas precozmente pueden producir desviación de la mandíbula en sentido anteroposterior o transversal. El manejo de las mordidas cruzadas se debe iniciar en el momento del diagnóstico, preferiblemente en edades tempranas, con el fin de tratarlas en el nivel primario de prevención. Objetivo: determinar el comportamiento de la maloclusión funcional causada por interferencias oclusales en niños con dentición mixta de la Escuela Primaria Mártires del Corynthia, entre octubre de 2019 y junio de 2021. Materiales y métodos: se realizó un estudio observacional descriptivo de corte transversal en la Escuela Primaria Mártires del Corynthia, del Área de Salud José Jacinto Milanés, del municipio de Matanzas, entre octubre de 2019 y junio de 2021. El universo estuvo conformado por 66 niños. Se utilizó una planilla de recolección de datos y se solicitó el consentimiento informado a los tutores de los niños. Resultados: las edades donde los niños presentaron mayor afectación fueron de 6 a 7 años y de 8 a 9 años, ambos rangos con un 10,6 %. El 27,3 % presentó interferencias oclusales y mordida cruzada posterior unilateral. El 48,5 % fue del sexo femenino y el 30,3 % tenían edades de 6 a 7 años. El 71,2 % eran simétricos y presentaron mordida cruzada posterior unilateral. Los simétricos y con línea media coincidente representaron un 36,4 %. Conclusiones: la maloclusión funcional más frecuente en niños con dentición mixta fue la mordida cruzada posterior unilateral, que se relacionó de manera directa con las interferencias oclusales. Las asimetrías faciales y la línea media desviada estuvieron asociadas a dicha maloclusión.

Introduction: early uncontrolled occlusal interferences can produce anterior-posterior jaw deflection. Management of cross-bites should be initiated at the time of diagnosis, preferably at early ages, in order to treat them at the primary level of prevention. Objective: to determine the behavior of functional malocclusion caused by occlusal interferences in children with mixed dentition from the Martires del Corynthia primary school between October 2019 and June 2021. Materials and methods: a cross-sectional, observational, descriptive study was carried out at the Martires del Corynthia Primary School, of the Jose Jacinto Milanes Health Area, Matanzas municipality, between October 2019 and June 2021. The universe consisted of 66 children. A data collection form was used and informed consent was requested from the children's guardians. Results: the ages where the children presented more affectation were from 6 to 7 years and from 8 to 9 years, both ranges with 10.6%. 27.3% presented occlusal interferences and posterior unilateral cross-bite. 48.5% were female and 30.3% were 6 to 7 years old. 71.2% were symmetrical and presented unilateral posterior cross-bite. Symmetric patients and with a coincident midline represented 36.4%. Conclusions: the most frequent functional malocclusion in children with mixed dentition was the unilateral posterior cross-bite, which was related to occlusal interferences in a direct way. Facial asymmetries and a deviated midline were associated with the before mentioned malocclusion.

Comparison between Simple Planas Indirect Tracks and occlusal splints for treatment of temporomandibular disorder-related headache: a randomized controlled clinical trial / Comparação entre Pistas Indiretas Planas Simples e placas miorrelaxantes para tratamento de dor de cabeça relacionada à disfunção temporomandibular: ensaio clínico randomizado

ABSTRACT BACKGROUND AND OBJECTIVES: Temporomandibular disorder-related headache (TMDH) is a very common clinical condition which manifests as pain around the temples. The treatment recommended in dentistry is occlusal splint. However, there is a device generally used in functional jaw orthopedics, called simple Planas indirect tracks (SPIT), which has been shown to be efficient in managing these headaches. This clinical trial aimed to compare SPIT and occlusal splints in the treatment of TMDH patients. METHODS: This randomized clinical trial included thirty-seven women who had TMDH for more than one year into three groups: GPIT treated with SPIT, GSPLINT treated with a Michigan splint, and a control group (CG) submitted to no treatment. The randomization was paired, that is, each new individual was assigned to a group sequentially. The number of headache days per month, average pain intensity, pain response to masseter and temporalis palpation, and days of pain drug use were collected and analyzed. The follow-up lasted for 3 months. RESULTS: Thirty-seven patients were included but 4 dropped out during treatment and 33 underwent intervention. Patients in GPIT exhibited superior results compared to GSPLINT and CG, with significant differences between groups for almost all variables. In GPIT, the number of headache days was reduced by 87.43%, pain intensity by 66.67%, and days of drug use by 88.42%, with significant improvement in all parameters compared to CG. In GSPLINT, the number of headache days decreased by 44.46% and days of drug use by 36.63%, while pain intensity increased by 46.67%; however, there was no significant difference in any of the parameters compared to CG. CONCLUSION: SPIT may be a good treatment option for patients with TMDH since these appliances have shown much more consistent results than occlusal splints. Further studies and with more individuals will be needed to confirm these findings.

RESUMO JUSTIFICATIVA E OBJETIVOS: A cefaleia secundária à disfunção temporomandibular (CDTM), é uma condição clínica muito comum, com dores nas têmporas. O tratamento padrão na odontologia são as placas miorrelaxantes, entretanto um aparelho da ortopedia funcional dos maxilares, chamado de Pistas Indiretas Planas Simples (PIPS), tem se demonstrado eficiente no controle dessas cefaleias. Este estudo clínico visou comparar as PIPS com as placas miorrelaxantes, no quadro álgico de CDTM. MÉTODOS: Este ensaio clínico randomizado incluiu 37 mulheres portadoras de CDTM há mais de um ano, que foram distribuídas aleatoriamente em três grupos: o GPIPS, no qual as pacientes foram tratadas com PIPS, o GPLACA, com uso de placas miorrelaxantes de Michigan e o grupo controle (GC), sem qualquer tratamento. A aleatorização foi pareada, sendo que cada participante era consecutivamente alocada em um grupo diferente. Foram coletados e analisados dias de cefaleia por mês, intensidade de dores, resposta álgica à palpação de masseter e temporal, bem como os dias de uso de fármacos. O acompanhamento foi de três meses. RESULTADOS: Das 37 pacientes iniciais, 4 desistiram do tratamento e apenas 33 foram submetidos a alguma intervenção. As pacientes do GPIPS apresentaram resultados muito superiores às do GPLACA e do GC, com diferenças significativas entre os grupos em quase todas as variáveis. No GPIPS, os dias de dor diminuíram 87,43%, a intensidade 66,67% e os dias de uso de fármacos analgésicos 88,42%, sendo estatisticamente significante a melhora em todos os parâmetros em relação ao GC. Já no GPLACA, os dias de dor diminuíram 44,46% e os dias de uso de fármacos 36,63%, mas a intensidade da dor aumentou 46,67%, porém sem diferença estatisticamente significante em nenhum parâmetro quando comparado ao GC. CONCLUSÃO: O uso do PIPS pode ser uma boa escolha de tratamento da CDTM, tendo apresentado resultados mais consistentes do que as placas miorrelaxantes. Mais estudos e com mais participantes são necessários para confirmar estes achados.

Evaluation of the occlusal contact area of molar dental implants comparing two different thicknesses (16 µm and 200 µm) of articulating occlusal papers and forces (200 and 250 N): a pivot in vitro study

Introduction: The goal of this pilot study was to evaluate the differences between checking occlusion on implants crowns using 16 or 200 µm thickness of articulating occlusal paper, and to compare the stained occlusal area between the groups after bite forces of 200 and 250 N. Methods: It was included 10 casts of articulated-type IV gypsum, 10 NiCr crowns, articulating occlusal papers (16 µm and 200 µm thick), and a compression test machine. Compressive forces (200 and 250 N.mm) were applied on models, to check the occlusal contact area of fixed and cemented crowns. The contact areas on the crowns were measured through images obtained by the scanning electron microscope. Statistical tests were performed considering the significant level of 5% (p≤0.05). Results: The stains found using 200 µm of articulating paper were higher than those with 16 µm, independent of the force applied. However, the stains obtained in lower teeth with different strengths (200 and 250N) marked with 16 µm articulating paper were not possible to score. The articulating paper variable had significant statistical results (p=0.002), while the variables force (p=0.443) and articulating paper-force interaction (p=0.607) were not significant. The mean area found in staining using the 200 µm and 16 µm papers was, respectively, 8.3380 mm2 and 3.4759 mm2. Conclusion: It was possible to confirm that 200 µm of articulating occlusal paper showed better and significant results to stain the occlusal area, permitting a more accurate adjustment independent of the force applied.

A comparative study based on the mandibular movement track and the movement parameters of the virtual articulator in simulating occlusal adjustment / 华西口腔医学杂志

OBJECTIVES@#This study aimed to compare the effects of virtual adjustment on occlusal interferences in mandibular posterior single crown and three-unit bridge restorations by using the mandibular movement track and the movement parameters of a virtual articulator.@*METHODS@#Twenty-two participants were recruited. Digital casts of the maxillary and mandibular arches were obtained using an intraoral scanner, and the jaw registration system was used to record the data of the mandibular movement track and the movement parameters of the articulator. Four kinds of restorations with 0.3 mm occlusal interferences were designed with dental design software. In particular, single crowns were designed for teeth 44 and 46, whereas three-unit bridges were designed for teeth 44-46 and 45-47, and the corresponding natural teeth were virtually extracted. Virtual adjustment of the restorations was performed using two dynamic occlusal recordings, namely, the mandibular movement track and the movement parameters of the virtual articulator. A reverse-engineering software was used to measure the root-mean-square of the three-dimensional deviation of the occlusal surfaces between natural teeth and the adjusted restorations. The differences between the two methods of virtual-occlusion adjustment were compared and analyzed.@*RESULTS@#For the same group of restorations, the three-dimensional deviation of the mandibular movement track group were lower than those of the virtual articulator group, and the differences were statistically significant (P<0.05). For the four groups of restorations adjusted by the same method, the three-dimensional deviation of the 46-tooth single crown was the largest and the smallest three-dimensional deviation was that of the 44-tooth single crown. Statistical differences existed between the 44-tooth single crown and the other groups (P<0.05).@*CONCLUSIONS@#For the occlusal design of posterior single crown and three-unit bridge, the mandibular movement track could be a more effective approach to virtual occlusal adjustment than the movement parameters of the virtual articulator.

Imaging study on the relationship between anterior and posterior occlusal planes and temporomandibular osteoarthrosis / 华西口腔医学杂志

OBJECTIVES@#The aim of this study was to compare the anterior and posterior occlusal plane characteristics of patients with different temporomandibular joint osseous statuses.@*METHODS@#A total of 306 patients with initial cone beam CT (CBCT) and cephalograms were included. They were divided into three groups on the basis of their temporomandibular joint osseous status: bilateral normal (BN) group, indeterminate for osteoarthrosis (I) group, and osteoarthrosis (OA) group. The anterior and posterior occlusal planes (AOP and POP) of the different groups were compared. Then, the regression equation was established after adjusting for confounding factors, and a correlation analysis between the occlusion planes and other parameters was performed.@*RESULTS@#SNA, SNB, FMA, SN-MP, Ar-Go, and S-Go were correlated with the occlusal planes. Relative to the BN and I groups, the FH-OP of the OA group increased by 1.67° on the average, FH-POP increased by 1.42° on the average, and FH-AOP increased by 2.05° on the average.@*CONCLUSIONS@#The occlusal planes were steeper in the patients with temporomandibular osteoarthrosis than in the patients without it, and the mandible rotated downward and backward. The height of the mandibular ramus, the mandibular body length, and the posterior face height were small. In clinical practice, attention should be given to the potential risk of temporomandibular joint osteoarthrosis in such patients. In addition, SNB, FMA, SN-MP, Ar-Go, S-Go, and occlusal planes had moderate correlations.

Implications of occlusal plane in diagnosis and treatment of malocclusion / 浙江大学学报·医学版

Occlusal plane (OP) is one of the essential factors affecting craniofacial morphology and function. The OP not only assists in diagnosing malocclusion but also serves as an important reference for making treatment plans. Patients with different types of malocclusions have different forms of OP. Compared with patients with standard skeletal facial type, the occlusal plane of patients with skeletal class Ⅱ and high angle is steeper, while that of patients with skeletal class Ⅲ and low angle is more even. In orthodontic treatment, adjusting and controlling the OP can promote the normal growth and development of the mandible in most patients with malocclusion during the early stage of growth, while causing favorable rotation of the mandible in some adults with mild-to-moderate malocclusion. For moderate-to-severe malocclusion, the OP rotation by orthodontic-orthognathic treatment can achieve better long-term stability. This article reviews the evolution of the definition of OP and its implications for diagnosing and the guiding treatment of malocclusion.

The removal of three kinds of occlusal veneers by Er: Yag laser / 华西口腔医学杂志

OBJECTIVES@#This study aimed to remove occlusal veneers of varied thicknesses and compositions by Er:Yag laser in vitro and analyze the interfacial microstructure between veneers and tooth that irradiated by laser, by which experimental evidence could be provided to support the non-invasive removal of occlusal veneerby laser.@*METHODS@#Fresh mandibular premolars extracted for orthodontic requirements were collected for tooth preparation. Three kinds of ceramic materials (Vita Suprinity, Vita Mark Ⅱ, and Upcera Hyramic) were selected to fabricate occlusal veneer with different thicknesses (1.0, 1.5, and 2.0 mm). One week later, Er:Yag laser (2.5 W and 3.5 W) was used to irradiate and remove the occlusal veneer and recorded the timespan. After the removal operation, the micro-morphologies of samples were examined by scanning electron microscope.@*RESULTS@#Upcera Hyramic veneer failed to be removed (>20 min); the operation span at 2.5 W, Vita Suprinity (96.0 s±16.0 s) was longer than Vita MarkⅡ(84.5 s±19.5 s) in the 1.0 mm group (P<0.05), and Vita Suprinity (246.5 s±13.5 s) was longer than Vita MarkⅡ(170.0 s±14.0 s) in the 1.5 mm group (P<0.05). At 3.5 W, Vita Suprinity (381.0 s±24.0 s) was longer than Vita MarkⅡ(341.5 s±26.5 s) in the 2.0 mm group.@*CONCLUSIONS@#Increasing laser power could shorten the operation span and facilitate the removal of occlusal veneers with the same thickness and composition. The occlusal veneer was sustained when insufficient laser power was applied. With the same laser power and ceramic thickness, laser penetration could interfere with the integral of the ceramic structure when the laser interacted with the bonding layer. With the same ceramic composition and laser power, the operation span and laser power increased with the thickness of the occlusal veneer. However, the laser was incapable of removing occlusal resin veneer directly.

Study on the fracture resistance of preparation designs of occlusal veneer and fiber posts in pulp-penetrating wedge-shaped defects / 安徽医科大学学报

Objective @# To investigate the effects of different occlusal veneer preparation designs and fiber posts on the fracture load and failure mode of endodontically treated maxillary premolars with pulp-piercing wedge-shaped defect．@*Methods @# 60 maxillary first premolars were randomly divided into group A and group B after Root Canal Therapy (RCT) and severe defects(n = 30) ．Group A was filled with glass fiber post and resin core，and group B was filled with resin core only．Then the occlusal veneer( G2) ，buccal-occlusal veneer( G3) and buccal-proximal-occlusal veneer ( G4 ) were applied to the isolated teeth．The teeth filled with composite resin ( G1 ) and full crown ( G5) were set as negative and positive control respectively，with 6 samples in each group．The sample was subjected to 5 000 hot and cold cycles and 20 000 vertical compression load aging．Finally，all the samples were loaded with static load until the sample broke at the speed of 0．5mm / min．The fracture load and failure mode of each sample were recorded. @*Results @# Both the fracture load in group A and B was G5 ＞G3 ＞G2 ＞G4 ＞G1，and the fracture load in G2，G3，G4，G5 was significantly higher than that in G1 (P＜0. 05) ，and there was no significant difference between group A and B (P＞0. 05) ．The fracture form of G3 was mostly unbonding of the repair body，which was conducive to re-repair．@*Conclusion @#Buccal ( occlusal) veneer is the most effective in repairing pulp-piercing wedge-shaped defects．The fiber post could not significantly enhance the fracture load of the pulp-piercing wedge- shaped defects teeth.

The efficacy of muscle function training combined with occlusal inducer in the treatment of malocclusion in children with OSA / 临床耳鼻咽喉头颈外科杂志

Objective:This study aims to investigate the clinical effectiveness of muscle function training combined with occlusal inducers in the treatment for children's malocclusion after obstructive sleep apnea（OSA） surgery. Methods:A total of 40 pediatric patients who underwent surgery for OSA at Shanghai Children's Medical Center, affiliated with Shanghai Jiao Tong University School of Medicine, from January 2020 to December 2021 were involved in this study. They were divided into a treatment group（n=20） and a control group（n=20）. The treatment group received muscle function training combined with occlusal inducers, while the control group received muscle function training alone. Cephalometric measurements of hard tissues were compared between the two groups before and 12 months after surgery. Additionally, the OSA-18 questionnaire, which includes 18 items to assess the life quality of children with OSA, was filled out before surgery, 6 months after surgery, and 12 months after surgery by these patients. Results:①The scores of sleep disorders, physical symptoms, emotional status, daytime sleepiness and energy status and the degree of influence on guardians in the two groups were significantly improved at 12 months after operation（P<0.05）. The scores of sleep disorders, physical symptoms, emotional status and the degree of influence on guardians in the treatment group were better than those in the control group（P<0.05）. ②Cephalometric data at 12 months after operation showed that the upper and lower alveolar seat angle（ANB）, Overbite, upper and lower central incisor angle（U1-L1） and Overjet in the treatment group were lower than those in the control group at 12 months after operation, and the difference was statistically significant（P<0.05）. Conclusion:Children with OSA can improve the dentition irregularity by muscle function training combined with occlusal inducer after operation, and the effect is better than that of muscle function training alone.