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.

Correlation between vertical dimension of occlusion and different facial measurements among a sample of sudanese adults / Correlación entre la dimensión vertical de la oclusión y diferentes medidas faciales en una muestra de adultos sudaneses

Aim: This study aimed to evaluate the correlation between vertical dimension of occlusion (VDO) and various facial measurements in a sample of Sudanese adults. Material and Methods: A total of 113 dental students (33 males and 80 females) with a mean age of 21.7±1.26 years were enrolled in this study. Different facial measurements including (Eye-Mouth, Eye-Eye, Eye-Ear, and Ear Height) were compared with two different measurements of VDO: N-Gn (from the tip of the nose to the tip of the chin), and Sn-Me (from the base of the nose to the bottom of the chin). Pearson's correlation coefficient test was utilized for the correlation between the measured parameters. A p-value of less than 0.05 was considered significant for all analyses. Results: A significant positive correlation was shown between all measured facial distances and both measured VDO distances. Though, the strongest correlation was seen for the eye-mouth distance (r= 0.725, p<0.001), while the weakest was for ear height (r= 0.254, p= 0.007). A paired t-test revealed a significant longer N-Gn distance than Sn-Me distance. Also, it has been shown that there were no significant differences between right and left sides of the face. Conclusion: The distance measured from the outer canthus of the eye to the angle of the mouth can be used to predict Subnasale-Menton (Sn-Me) distance.

Objetivo: Este estudio tuvo como objetivo evaluar la correlación entre dimensión vertical oclusal (DVO) y varias medidas faciales en una muestra de adultos sudaneses. Material y Métodos: Un total de 113 estudiantes de odontología (33 hombres y 80 mujeres) con una edad media de 21,7 ± 1,26 años se inscribieron en este estudio. Se compararon diferentes medidas faciales que incluyen (ojo- boca, ojo-ojo, ojo-oído y altura de la oreja) con dos medidas diferentes de DVO: N-Gn (desde la punta de la nariz hasta la punta del mentón) y Sn -Yo (desde la base de la nariz hasta la parte inferior del mentón). Se utilizó la prueba del coeficiente de correlación de Pearson para la correlación entre los parámetros medidos. Un valor de p inferior a 0,05 se consideró significativo para todos los análisis. Resultados: Se mostró una correlación positiva significativa entre todas las distancias faciales medidas y ambas distancias DVO medidas. Sin embargo, la correlación más fuerte se observó para la distancia ojo-boca (r=0,725, p<0,001), mientras que la más débil fue para la altura de las orejas (r=0,254, p=0,007). Una prueba de t pareada reveló una distancia N-Gn significativamente más larga que la distancia subnasal-mentón. Además, se ha demostrado que no hubo diferencias significativas entre los lados derecho e izquierdo de la cara. Conclusión: La distancia medida desde el canto externo del ojo hasta el ángulo de la boca puede utilizarse para predecir la distancia subnasal-mentón.

Fiberglass versus cast metal posts: a practical review based on mechanical properties / Pinos de fibra de vidro versus metal fundido: uma revisão prática baseada em propriedades mecânicas

The current review aimed to compare the mechanical properties and clinical behavior of fiberglass and cast metal posts. It included in-vitro studies, finite element analysis, clinical studies, and systematic reviews that evaluated fiberglass and metal posts with reliable methodologies. The reports in the literature diverge on tooth failure modes and stress distributions in the root according to different posts. Investigations suggest that fiberglass posts are preferable because their elastic modulus is similar to dentin. Other studies mention that the flexibility of fiber posts may damage the interface. The fracture load values of different studies could not be compared. The presence of a ferrule seems beneficial. Cast metal posts provide higher characteristic strength to the set but with more unfavorable failures. Intraradicular posts with a lower elastic modulus produce more stress between the cement layer and dentin. In conclusion, fiberglass and cast metal posts can be used with a ferrule. Cast metal posts seem more appropriate for weakened teeth. The presence of a ferrule benefits the system. Weakened teeth tolerate higher loads when restored with cast metal posts, but when these posts fail, the only solution is tooth extraction. Clinical follow-ups cannot yet detect differences between the survival rates of intraradicular fiberglass and cast metal posts (AU)

O objetivo da presente revisão foi comparar as propriedades mecânicas e o comportamento clínico de pinos de fibra de vidro e núcleos metálicos fundidos. Estudos laboratoriais, analise por elementos finitos, estudos clínicos e revisões sistemáticas que avaliaram pinos de fibra de vidro e metálicos, com metodologia confiável foram selecionados. A literatura mostra-se bastante controversa sobre os modos de falha do dente e a distribuição de tensões na raiz de acordo com diferentes tipos de pinos. Algumas investigações sugerem que pinos de fibra de vidro são preferíveis porque seu módulo de elasticidade é semelhante ao da dentina, enquanto outras mencionam que a flexibilidade do pino de fibra pode ser prejudicial à interface adesiva. Os valores de carga de fratura em diferentes estudos não podem ser comparados. A presença de férula é benéfica. O núcleo metálico fundido resulta em maior resistência característica do conjunto, mas falhas mais desfavoráveis. Também, pinos com menor módulo geram mais tensão entre a camada de cimento e a dentina. Em conclusão, verificou-se que tanto pino de fibra de vidro como núcleo metálico fundido podem ser utilizados quando a férula está presente. Os núcleos metálicos fundidos parecem ser mais indicados para dentes fragilizados. É evidente que a presença de férula é benéfica para o sistema. Dentes fragilizados toleram cargas maiores quando restaurados com núcleos metálicos fundidos; porém, quando falham, a única solução é a extração do dente. Os acompanhamentos clínicos ainda não são capazes de detectar diferença entre as taxas de sobrevivência dos pinos de fibra de vidro e núcleos metálicos (AU)

Fixed-prosthodontics in Nigerian private practice settings

Context: Private practice dentistry is predominant in Nigeria. Audits of fixed-prosthodontic practice in these settings are rare and will highlight capacity and guide training. This study aimed to assess the scope and quality of fixed-prosthodontic practice in such settings in Nigeria. Objectives: The study sought to assess: Participants' sociodemographic and their diagnostic and preoperative practices. The quality of impression making and operative technique, reviews and maintenance, temporization practices and communication with the laboratory.The range of treatments given and provision of advanced treatments. Materials and Methods: An adapted questionnaire was administered electronically on Nigerian dentists practicing fixed-prosthodontics in private practice settings. Retrieved data underwent descriptive statistics and associations were tested with the Fischer's Exact and Chi-Square tests using IBM SPSS Statistics version 21. Statistical significance was set at p≤0.05. Results: A total of 100 valid responses with a male:female ratio of 2.1:1 from 16 states wereretrieved. Fifty-nine participants had only first degrees and mean experience was 14.3±9.5 years. There were 27 adequate responses with regards to range of treatments offered. Sixty-three participants practiced direct temporization. Twenty-one and 14 participants regularly practiced implantology and CAD/CAM dentistry respectively. Direct temporization was significantly associated with increasing education (X2=6.03, p=0,05) and experience (X2=13.2, p=0.03). Conclusion: Only a few Nigerian dentists in private practice gave an adequate range of treatment. Most of them prefer direct temporization. Implantology and CAD/CAM dentistry practice are improving, but are still not very common.

Research progress on the low-temperature degradation of zirconia in prosthetic dentistry / 中华口腔医学杂志

Zirconia is widely used in the field of dentistry because of its superior mechanical and esthetic characteristics. However, the tetragonal zirconia polycrystal restorations commonly used in clinics will degrade at low temperatures in the oral environment, resulting in increased surface roughness, microcracks, and decreased mechanical properties. Low-temperature degradation of zirconia can be affected by grain size, stress, stabilizer content and type, surface treatment, sintering conditions, and other factors. Through a literature review and analysis, this review summarizes the research progress on the low-temperature degradation of zirconia in prosthetic dentistry to provide references for the improvement of zirconia in clinical and research applications.

Guideline for prosthetic dentistry in elderly patients / 中华口腔医学杂志

China has entered an aging society. The incidence rate of dental defects, dentition defects and edentulism in elderly patients is high, and the number of patients is increasing. The physiological and pathological conditions are complex for the elderly. Moreover, the expectation of dental restoration is also increasing, which is a great challenge in clinic. Currently, few relevant guidelines or standards have been issued nationally or internationally. The Society of Prosthodontics, Chinese Stomatological Association, based on extensive solicitation of opinions and reference to relevant literature, has set an application guideline after extensive discussions and revisions. The guideline covers the common clinical treatment scenarios for prosthetic dentistry in elderly patients. The present guideline consists of general principles, basic workflows and important considerations to provide reference for prosthodontist and relevant medical practitioners.

Rehabilitación protésica en odontopediatría y sus efectos en la modificación conductual de un niño / Prosthetic rehabilitation in pediatric dentistry and its effects on the behavioral modification of a child

La caries de la temprana infancia puede afectar severamente la dentición primaria que requiere tratamientos complejos y en ocasiones la extracción del diente afectado. Se presenta informe de caso sobre la rehabilitación dental integral de un paciente de 6 años, la evolución de su comportamiento y la mejora en su calidad de vida, autoestima e interacción social. El plan de tratamiento incluyó una fase de adaptación a la consulta odontológica, eliminación de caries, restauración dental, exodoncias y elaboración de dos prótesis removibles. Al inicio del tratamiento presentó temor y rechazo al tratamiento, pero con el avance del proceso rehabilitador odontológico y la evidencia de los resultados, el comportamiento del niño fue de aceptación y colaboración. Su evolución positiva de comportamiento se presentó también en sus relaciones sociales, aumentó la interacción con otras personas y su participación en juegos con otros niños. La rehabilitación protésica contribuyó a recuperar las funciones de masticación y fonación. La renovación de la estética dental produjo un significativo cambio de conducta, mejora en su autoestima con un impacto psicológico positivo en su calidad de vida

Early childhood caries can severely affect the primary dentition requiring complex treatments and sometimes the extraction of the affected tooth. A case report is presented on the comprehensive dental rehabilitation of a 6-year-old patient, the evolution of his behavior and the improvement in his quality of life, self-esteem and social interaction. The treatment plan included a phase of adaptation to the dental consultation, elimination of cavities, dental restoration, extractions and elaboration of two removable prostheses. At the beginning of the treatment, he presented fear and rejection of the treatment, but with the progress of the dental rehabilitation process and the evidence of the results, the child's behavior was one of acceptance and collaboration. Their positive behavior evolution was also present in their social relationships, increased interaction with other people and their participation in games with other children. Prosthetic rehabilitation contributed to recovering the functions of chewing and phonation. The renovation of dental aesthetics produced a significant change in behavior, an improvement in their self-esteem with a positive psychological impact on their quality of life

Prosthodontic Rehabilitation of Bilateral Maxillary Lateral Incisors Agenesis: A Case Report with One-Year Follow-Up

ABSTRACT@#Globally, non-syndromic tooth agenesis is commonly seen in clinical practice. However, its management is often complex and requires a multidisciplinary team approach for the maximal outcome. While various treatment options are possible, considerations for the treatment are not only based on the dentofacial conditions but also cultural and social background and personal preference of the patient. Thus, patientcentred care approach should always be practised for an optimal outcome. In the present case, a patient with established craniofacial growth presenting with bilateral agenesis of maxillary lateral incisors and over-retained deciduous maxillary left canine sought for aesthetic improvements. The patient did not prefer any orthodontic treatment citing a prolonged treatment duration and sub-optimal motivation as a hindrance. Thus, a prosthodontic only approach was taken by providing a conventional cantilever bridge and ceramic veneers to achieve the aims of treatment. This article discusses the possible limitation of such prosthodontic only solution in managing tooth agenesis.

Fracture resistance and strain analysis of zirconia copings with vertical knife edge and three horizontal finish line designs; chamfer, deep chamfer and shoulder with two cementation techniques / Resistência à fratura e análise de deformação de copings de zircônia com término cervical em lâmina de faca e três términos horizontais; chanfro, chanfro largo e ombro com duas técnicas de cimentação

Objective: The purpose of this in vitro study is to evaluate the effect of four finish line configurations and two cement types on the fracture resistance of zirconia copings. Material and Methods: Forty yttrium tetragonal zirconia polycrystals copings were manufactured on epoxy resin dies with four preparation designs: knife edge, chamfer, deep chamfer 0.5, 1 mm and shoulder 1 mm. The copings were cemented with two cement types (glass ionomer and resin cement); (n = 5). Two strain gauges were attached on each coping before they were vertically loaded till fracture with a universal testing machine. Data were analyzed by 2-way analysis of variance ANOVA (p < .05). Fractured specimens were examined for mode of failure with digital microscope. Results: Knife edge showed the highest mean fracture resistance (987.04 ± 94.18) followed by Chamfer (883.28 ± 205.42) followed by Shoulder (828.64 ± 227.79) and finally Deep chamfer finish line (767.66 ± 207.09) with no statistically significant difference. Resin cemented copings had higher mean Fracture resistance (911.76 ± 167.95) than glass ionomer cemented copings (821.55 ± 224.24) with no statistically significant difference. Knife edge had the highest strain mean values on the buccal (374.04 ± 195.43) and lingual (235.80 ± 103.46) surface. Shoulder finish line showed the lowest mean strain values on the buccal (127.47 ± 40.32) and lingual (68.35 ± 80.68) with no statistically significant difference. Resin cemented copings had higher buccal (295.05 ± 167.92) and lingual (197.38 ± 99.85) mean strain values than glass ionomer copings (149.14 ± 60.94) and (90.27 ± 55.62) with no statistically significant difference. Conclusion: Vertical knife edge finish line is a promising alternative and either adhesive or conventional cementation can be used with zirconia copings (AU)

Objetivo: O objetivo deste estudo in vitro é avaliar o efeito de quatro configurações de términos cervicais e dois tipos de cimentos na resistência à fratura de copings de zircônia. Material e Métodos: Quarenta copings de zircônia tetragonal policristalina estabilizada por ítrio foram confeccionados em matrizes de resina epóxi com quatro tipos de términos cervicais: lâmina de faca, chanfro, chanfro largo 0,5, 1 mm e ombro 1 mm. Os copings foram cimentados com dois tipos de cimento (ionômero de vidro e cimento resinoso); (n = 5). Dois extensômetros foram fixados em cada coping antes de serem carregados verticalmente até a fratura com uma máquina de teste universal. Os dados foram analisados por análise de variância ANOVA 2 fatores (p < 0,05). Os espécimes fraturados foram examinados quanto ao modo de falha com microscópio digital. Resultados: A Lâmina de faca apresentou a maior média de resistência à fratura (987,04 ± 94,18) seguida pelo Chanfro (883,28 ± 205,42), pelo Ombro (828,64 ± 227,79) e finalmente o Chanfro largo (767,66 ± 207,09), sem diferença estatisticamente significativa. Os copings cimentados com cimento resinoso apresentaram maior média de resistência à fratura (911,76 ± 167,95) em relação aos copings cimentados com ionômero de vidro (821,55 ± 224,24), sem diferença estatisticamente significativa. A lâmina de faca apresentou os maiores valores médios de deformação na superfície vestibular (374,04 ± 195,43) e lingual (235,80 ± 103,46). O término em ombro apresentou os menores valores médios de deformação na superfície vestibular (127,47 ± 40,32) e lingual (68,35 ± 80,68), sem diferença estatisticamente significativa. Os copings cimentados com resina apresentaram maiores valores médios de deformação na superfície vestibular (295,05 ± 167,92) e lingual (197,38 ± 99,85) do que os copings cimentados com ionômero de vidro (149,14 ± 60,94) e (90,27 ± 55,62), sem diferença estatisticamente significativa. Conclusão: O término cervical em lâmina de faca é uma alternativa promissora e a cimentação adesiva ou convencional pode ser usada na cimentação de copings de zircônia. (AU)

Prosthodontic practice during the COVID-19 pandemic: prevention and implications

Abstract: The objective of this review is to identify preventive measures for COVID-19 to safeguard dental professionals providing prosthodontic dental care. Electronic searches were performed in PubMed, Scopus, and Cochrane databases using the following descriptors and/or words: "COVID-19," "SARS-CoV-2," "Dental practice," "Prosthodontics," and "Dental infection control." Prosthodontists are at high risk for exposure to the novel coronavirus through aerosols and possibly contaminated surfaces and indirect contact with dental laboratories and dental technicians through impressions, dental stone casts, and fixed and removable prosthetic appliances. Therefore, preventive measures should be implemented, including performing emergency treatments only, rescheduling patients with suspected disease, disinfecting surfaces and prosthodontic materials with biocidal substances, and using protective equipment such as N95 masks, disposable gowns, and face-shields.

Rehabilitación protésica en paciente pediátrico con displasia ectodérmica / Reabilitação protética em paciente pediátrico com displasia ectodérmica / Prosthetic rehabilitation in pediatric patient with ectodermal dysplasia

La displasia ectodérmica es un trastorno congénito caracterizado por el desarrollo anormal de dos o más derivados de ectodermo, como el cabello, glándulas sudoríparas, uñas y dientes. Los tipos más comunes son la Hipohidrótica/ Anhidrótica y la Hidrótica. El objetivo del reporte decaso es mostrar las características de un paciente con displasia ectodérmica anhidrótica, el tratamiento odontológico realizado y los resultados logrados. Reporte de caso: Paciente masculino de 5 años con Displasia Ectodérmica Anhidrótica acude en compañía de su madre a la clínica de especialidad de Odontopediatría de la ENES UNAM León, quien reporta como motivo de consulta: "que le coloquen dientes". En la exploración extraoral se observa cabello escaso y fino, ausencia de cejas y pestañas, proquelia, tercio inferior disminuido, en la evaluación intraoralse observa oligodoncia con presencia de dientes cónicos en 52 y 62, en la ortopantomografía se observa en proceso de erupción los dientes 11 y 21. Diagnóstico bucal: Oligodoncia, dientes cónicos, retardo de la erupción, reborde alveolar atrófico-estrecho y disminución de la dimensión vertical. Tratamiento:Rehabilitación de coronas de disilicato de litio en los dientes 52 y 62, prótesis parcial removible con tornillo de expansión en el maxilar superior y, en la mandíbula, prótesis total con tornillo de expansión. Se generó una mejor función masticatoria, fonación, peristaltismo lingual y mayor autoestima del paciente. Conclusiones: La rehabilitación temprana en pacientes con Displasia Ectodérmica y su tratamiento integral, promueve el crecimiento de las estructuras bucales, función, estética y autoestima del paciente

A displasia ectodérmica é um distúrbio congênito caracterizado pelo desenvolvimento anormal de dois ou mais derivados do ectoderma, como cabelos, glândulas sudoríparas, unhas e dentes. Os tipos mais comuns são Hipohidrótico / Anidrótico e Hidrótico. O objetivo do relato de caso é mostrar as características de um paciente com Displasia Ectodérmica anidrótica, bem como o tratamento odontológico realizado e os resultados alcançados. Relato de caso: Paciente do sexo masculino, 5 anos, portador de Displasia Ectodérmica Anidrótica, vai com sua mãe à Clínica de Odontopediatria da ENES UNAM León, quem relata como motivo da consulta "Colocar os dentes". No exame extra-oral, são observados cabelos finos e esparsos, ausência de sobrancelhas e cílios, terço inferior diminuído, no exame intraoral, oligodontia com presença de dentes cônicos 52 e 62, na radiografia panorâmica mostra os dentes 11 e 21. Diagnóstico odontológico: Oligodontia, dentes cônicos, erupção tardia, rebordo alveolar atrófico estreito e diminuição da dimensão vertical. Tratamento:Reabilitação de coroas de dissilicato de lítio nos dentes 52 e 62, prótese parcial removível com parafuso de expansão na maxilar superior e prótese total com parafuso de expansão na mandíbula. Geraram melhor função mastigatória, fonação, peristaltismo lingual e maior autoestima do paciente. Conclusões: A reabilitação precoce em pacientes com displasia ectodérmica e seu tratamento abrangente promove o crescimento das estruturas orais, função, estética e auto-estima do paciente

Ectodermal dysplasia is a congenital disorder characterized by the abnormal development of two or more ectoderm derivatives, such as hair, sweat glands, nails and teeth. The most common types are Hypohydrotic / Anhydrotic and Hydrotic. The objective of the case report is to show the characteristics of a patient with Ectodermal Anhydrotic Dysplasia, as well as the dental treatment performed and the results achieved. Case Report:A 5-year-old male patient with ectodermal anhydrotic dysplasia attends with his mother to the Pediatric dentistry clinic at ENES UNAM León, who reports as a reason for consultation "of having teeth placed". In the extraoral exam, there is an evident lack of eyebrows and eyelashes, thin hair, prochelia and decreased lower facial third is observed. Within

The question about the numerical value and quantitative data transfer of implant prosthodontics-orom experience guidance to digital guidance / 华西口腔医学杂志

The correct implant site design and placement are the basic clinical techniques that must be known for implant restoration. For a long time, most implants have been placed by free hands, and the choice of site is mostly dependent on the accumulation of long-term experience of the surgeon. The selection of implant site guided by this experience analogy logic is often based on the surgeon's level of experience,which often makes it very easy to produce complications related to the implant restoration of the incorrect site. In contrast, a clinical program using digital guidance and real-time measurable verification has emerged based on the restoration-oriented implantation concept, which marks the formation of an accurate, measurable and verifiable whole-process digital implant prototype. Furthermore, from the perspective of surveying, the numerical requirements that digital implant restoration relies on are actually incomplete to the four elements of measurement, which leading to the doubts about its authenticity. This article will question the numbers in implant restoration, and conduct a preliminary demonstration, and propose a new reliable actual measurement and verification method of the correct location and the numerical requirements of the restoration space and a new clinical program that relies on numbers from the perspective of the evolution of digital restoration, guided implantology and actual measurement technology. And this article further discusses the current mainstream implant restoration technology based on experience analogy which cannot effectively support the whole process of digital implant restoration and provides a new logical cognitive basis for the final realization of the entire process of digital implant restoration.

Clinical performance of intraoral digital impression for fixed prosthodontics: a Meta-analysis / 华西口腔医学杂志

OBJECTIVES@#To analyze the clinical performance of the intraoral digital impression (IDI) in the fixed prosthodontics.@*METHODS@#Databases of Medline (Ovid), EMBASE, Cochrane Central Register of Controlled Trials, and CNKI were searched for randomized controlled trial (RCT) on the use of IDI in fixed prosthodontics until May 2020. Two reviewers independently screened literature, extracted data, and assessed the risk of bias of included studies. A Meta-analysis was conducted when available.@*RESULTS@#Eleven RCTs involving 618 patients were included in this study. A total of 2 and 3 studies had low and high risks of bias, respectively, and other included studies had a medium risk of bias. Results illustrated that the IDI group could shorten the impression-taken time [SMD=-5.63, 95%CI (-11.25, -0.01), @*CONCLUSIONS@#Evidence indicated a good clinical performance of IDI for fixed prosthodontics. Notably, high-quality studies are expected to further support the conclusion.

Questions about the numerical value and quantitative data transfer of tooth preparation-from experience guidance to digital guidance / 华西口腔医学杂志

Tooth preparation is a common operation in dental clinical practice. This procedure is irreversible and invasive from the point of view of tooth preservation. Conditions of the abutment tooth, treatment methods, and restoration materials for target restoration affect tooth preparation. To achieve the goals of tooth tissue preservation, dental pulp protection, and periodontal health, dentistry professionals agreed on the importance of minimizing the amount of tooth reduction. The foundations for realizing this consensus are as follows. First, the available restoration materials with improved comprehensive performance need less target restoration space. Next, teeth can be prepared under a digital guide, and the real-time measurement of restoration space can be verified due to the invention of digital technologies for the analysis of the quantity and shape of the prepared tooth and tooth measurement. Moreover, guiding methods for preparation have been developed from freehand operation under the naked eye based on accumulated personal experience to digital-guidance jointing microscope. These innovations indicate the creation of a prototype of guided prosthodontics that is precise and applies real-time measurement throughout the process of tooth preparation. From the perspective of the evolution of digital, guided, and micro prosthodontics, this article raised seven questions about the numerical value and quantitative data transfer of tooth preparation and evaluated the authenticity of existing numerical requirements from the perspective of the four elements of measurement. Identifying unified measuring methods and developing measuring tools with a precision of hundred or ten microns will be the key to solving the problem about the authenticity of numerical measurement. Furthermore, this paper summarizes the methods of how to control tooth reduction and explains in depth why the currently dominant tooth preparation technology, which is based on empiricism, cannot effectively achieve the goals in digital prosthodontics. Therefore, we strongly call for rebuilding the digital foundation of prosthodontic treatment immediately.

Standard operating procedure for microscopic tooth preparation / 中华口腔医学杂志

Tooth preparation is the primary and core operation technique for prosthodontics. Microscopic tooth preparation can improve the accuracy and efficiency of the operation. Experts from Society of Prosthodontics, Chinese Stomatological Association formulated the standard operating procedure for microscopic tooth preparation, so as to standardize its design points and operating procedures, highlight the difference between this novel technique and the traditional naked eye tooth preparation and promote the application of microscopic tooth preparation.

Flexural strength of polyether ether ketone high-performance polyether in comparison with base metal alloy and zirconia ceramic / Resistencia a la flexión del poliéter éter cetona poliéter de alto rendimiento en comparación con la aleación de metal base y la cerámica de circonio

Optimal flexural strength is a critical prerequisite for prosthetic frameworks. This study aimed to assess the flexural strength of polyether ether ketone (PEEK) polymer compared to a base metal alloy and high-strength Zirconia ceramic commonly used in prosthodontic treatments. Materials and Methods: In this in vitro, experimental study, 10 bar-shaped samples measuring 18×5×2mm were fabricated of each the PEEK polymer, nickel-chromium base metal alloy and zirconia ceramic. Half of the samples in each group were subjected to 5000 thermal cycles between 5°C - 55°C with 20 seconds of dwell time and 20 seconds of transfer time to simulate oral conditions. All samples then underwent three-point bending test. Two-way ANOVA followed by Tukey's test were applied to compare the mean flexural strength of the groups with and without thermocycling at 0.05 level of significance. Results: The flexural strength of base metal alloy, Zirconia and PEEK was 1387.70±45.50 MPa, 895.13±13.99 MPa and 192.10±5.37 MPa, respectively. The difference was significant among the groups (p<0.001). Thermocycling had no significant effect on the flexural strength of samples in any group (p=0.306). Conclusion: PEEK high-performance polymer had a lower flexural strength than base metal alloy and Zirconia ceramic, and its flexural strength was not affected by thermocycling. PEEK seems to be able to resist masticatory forces in the oral cavity pending further in vitro and clinical studies.

La resistencia a la flexión óptima es un requisito previo crítico para los marcos protésicos. Este estudio tuvo como objetivo evaluar la resistencia a la flexión del polímero de poliéter éter cetona (PEEK) en comparación con una aleación de metal base y cerámica de Zirconia de alta resistencia comúnmente utilizada en tratamientos de prostodoncia. Materiales and Métodos: En este estudio experimentalin vitro, se fabricaron 10 muestras en forma de barra de 18 × 5 × 2mm de cada polímero PEEK, aleación de metal base de níquel-cromo y cerámica de circonio. La mitad de las muestras en cada grupo fueron sometidas a 5000 ciclos térmicos entre 5°C - 55°C con 20 segundos de tiempo de permanencia y 20 segundos de tiempo de transferencia para simular condiciones orales. Todas las muestras se sometieron a una prueba de flexión de tres puntos. Se aplicó ANOVA bidireccional seguido de la prueba de Tukey para comparar la resistencia a la flexión media de los grupos con y sin termociclado a un nivel de significancia de 0.05. Resultados: La resistencia a la flexión de la aleación de metal base, Zirconia y PEEK fue de 1387,70 ± 45,50 MPa; 895,13 ± 13,99 MPa y 192.10 ± 5,37 MPa, respectivamente. La diferencia fue significativa entre los grupos (p<0,001). El termociclado no tuvo un efecto significativo sobre la resistencia a la flexión de las muestras en ningún grupo (p=0,306).Conclusión:El polímero de alto rendimiento PEEK tiene una resistencia a la flexión más baja que la aleación de metal base y la cerámica de circonio, y su resistencia a la flexión no se vio afectada por el termociclado. PEEK parece ser capaz de resistir las fuerzas masticatorias en la cavidad oral, con la necesidad de más estudios in vitroy clínicos.

How many implants are needed for mandibular full-arch rehabilitation?

Aim: To analyze the stress distribution at the peri-implant bone tissue of mandible in full-arch implant-supported rehabilitation using a different number of implants as support. Methods: Three-dimensional finite element models of full-arch prosthesis with 3, 4 and 5 implants and those respective mandibular bone, screws and structure were built. ANSYS Workbench software was used to analyze the maximum and minimum principal stresses (quantitative analysis) and modified von Mises stress (qualitative analysis) in peri-implant bone tissue after vertical and oblique forces (100N) applied to the structure at the cantilever site (region of the first molars). Results: The peak of tensile stress values were at the bone tissue around to the distal implant in all models. The model with 3 implants presented the maximum principal stress, in the surrounding bone tissue, higher (~14%) than the other models. The difference of maximum principal stress for model with 4 and 5 implants was not relevant (~1%). The first medial implant of the model with 5 implants presented the lower (17%) stress values in bone than model with 3 implants. It was also not different from model with 4 implants. Conclusion: Three regular implants might present a slight higher chance of failure than rehabilitations with four or five implants. The use of four implants showed to be an adequate alternative to the use of classical five implants

Dental implants placed buccally to the mandibular canal in molar regions with severe vertical bone loss: case reports

Introduction: Alveolar bone loss in posterior regions of the mandible is a serious limiting factor for the installation of osseointegrated dental implants. New surgical procedures are needed to circumvent the lack of vertical bone. Objective: The objective of this study was to present an alternative technique for dental implants in the lateral posterior region of the mandible in patients with severe vertical ridge atrophy Case Reports: Four patients with the specific anatomical characteristics that met the requirements of the technique were selected. Six implants were inserted buccally to the mandibular canal and were restored after at least two months of healing time. The mean follow up period of the implants was 3 years. No implant was lost during this time. All of them remained in excellent clinical condition and met the aesthetic criteria and functional demands of occlusion. Conclusion: The technique presented here proved to be minimally invasive, safe, conservative and effective as an alternative treatment option for dental rehabilitation in mandibular posterior regions with severe bone atrophy. However, it requires experience, preparation and skill of the professional in order not to damage the inferior alveolar nerve and at the same time install the implant in the correct position, thus allowing its functional and aesthetic rehabilitation.

Introdução: A perda óssea alveolar severa em região posterior de mandíbula é um sério fator limitante para instalação de implantes dentários osseointegráveis. Novas técnicas cirúrgicas são necessárias visando contornar a falta de osso vertical. Objetivo: O objetivo deste estudo foi apresentar uma técnica alternativa de inserção de implante dentário na região posterior lateral da mandíbula em pacientes com atrofia vertical severa de rebordo alveolar. Relatos de casos : Foram selecionados 4 pacientes com características anatômicas específicas que atendiam aos requisitos da técnica. Seis implantes foram instalados lateralmente ao canal mandibular por vestibular e foram restaurados após o tempo de cicatrização de pelo menos dois meses. A média da avaliação de seguimento do implante foi de 3 anos. Nenhum implante foi perdido e todos eles atenderam às exigências estéticas e funcionais da oclusão, estando em ótimas condições clínicas. Conclusão: A técnica mostrou-se minimamente invasiva, segura, conservadora e eficaz como alternativa de tratamento para reabilitação dentária em regiões posteriores de mandíbula com atrofia óssea severa. Entretanto, ela requer experiência, preparo e habilidade do profissional que visa não lesionar o nervo alveolar inferior e, ao mesmo tempo, instalar corretamente o implante em uma posição que permita sua restauração funcional e estética.

Evaluation of the success rates of immediate implant placement in anterior and posterior regions success rates of immediate implant: a retrospective study

Introdution: Immediate implants placement has shown contradictory results inthe posterior region. Objective: The aim of the study was to compare the successrate and predictability of the short-term treatment using immediate implants inanterior and posterior regions. Methods: A total of 1000 dental charts wereanalyzed, of which 43 were included in the study: anterior (n=20) and posterior(n=23). The inclusion criteria were: tooth extraction indication, immediate single-tooth implant placement and at least twelve months of follow-up with functionalimplant. The success rates were based on the criteria I. and II. from the healthscale for dental implants proposed at the International Congress of Oral ImplantDentistry: no pain; no mobility, until 4 mm of bone loss, no exudate. P-value <0.05was considered significant. Results: The total success rate of immediate implantswas 97.7% for immediate implants in function for at least 12 months. The use ofbiomaterial (p=0.03) and temporary prosthesis (p<0.0001) were significantly higherin the anterior group. There was no significant difference in implant failure betweengroups (p=0.47). There was no statistical difference between the groups, consideringage, sex, extraction reason, initial torque immediately following implantplacement, treatment time and implant platform type (p> 0.05). Conclusion: Itmay be concluded that the anterior and posterior regions present a high short-term success rate when the immediate implant technique was used.

Introdução: A utilização de implante imediato em regiões posteriores temapresentado resultados contraditórios. Objetivo: O objetivo deste estudo foicomparar o índice de sucesso e previsibilidade à curto prazo de implantes imediatosinstalados em regiões anterior e posterior. Métodos: Um total de 1000 prontuáriosforam analisados, dos quais 43 foram incluídos neste estudo: Anterior (n=20) eposterior (n=23). Os critérios de inclusão foram: Indicação de extração dentária,instalação de implantes imediatos unitários, no mínimo doze meses de segmentocom implante funcional. Os critérios de sucesso foram baseados na escala desaúde dos implantes dentários do Congresso Internacional de Implantologia Oral,eixo I. e II.: ausência de dor, ausência de mobilidade, ausência de exudato e perdaóssea de até 4 mm. Valor de p<0.05 foi considerado estatisticamente significante.Resultados: O índice de sucesso dos implantes imediatos foi de 97,7% paraimplantes em função por pelo menos 12 meses. O uso de biomaterial (p=0,03) eprótese provisória (p<0,0001) foi significantemente maior em região anterior.Não foi encontrado diferença significante quanto a falha dos implantescomparando os dois grupos (p=0,47). Não houve diferença estatisticamentesignificante entre os grupos, considerando a idade, gênero, motivo da extração,torque inicial, tempo de tratamento e tipo de plataforma do implante (p>0,05).Conclusão: Pode-se concluir que as regiões anterior e posterior apresentaramalta taxa de sucesso a curto prazo quanto a técnica de implante imediato.