Endocrown Feasibility for Primary Molars: A Finite Element Study.

OBJECTIVE: To study the possibility of using pediatric endocrowns to restore the second primary molar using three-dimensional (3D) finite element analysis. DESIGN: A 3D finite element model was built for a pediatric mandibular molar, starting with laser scanning a naturally extracted tooth. The access cavity had an elliptic shape with 6 mm width, 4 mm height, and 2 mm depth with a wall taper angle of 5 degrees.Two materials (Zr and E-max) were tested for the endocrown and two cementing materials (glass ionomer and resin cement) with 20 to 40 µm thickness. Twelve case studies were reported within this research as the applied load of 330 N was tested with three angulations vertical, oblique at 45 degrees, and laterally. RESULTS: Twelve linear static stress analyses were performed. The resultant stresses and deformations' distribution patterns did not alter much, and values were within the threshold of physiological tolerance. Deformations were negligibly changed with changing endocrown and cement materials. In contrast, endocrown stresses indicated zirconia endocrown would have a long lifetime, while E-max one will have a relatively short lifetime. CONCLUSIONS: Analysis results indicated that bone was negligibly affected by changing endocrowns and cementing materials. Both tested endocrown materials can be used safely. Zirconia endocrowns may have a much longer lifetime than E-max.

Pediatric Stainless-Steel Crown Cementation Finite Element Study.

OBJECTIVE: To study the effect of using different cement types under pediatric stainless-steel crown (SSC) around mandibular second primary molar using three-dimensional (3D) finite element analysis. MATERIALS AND METHODS: A 3D finite element model was built for pediatric mandibular molar by laser scanning of natural extracted tooth. Four types of cement (zinc phosphate, glass ionomer, resin-modified glass ionomer, and resin) of 200 µm layers thickness were tested under a stainless-steel crown of 130-µm thickness. Twelve case studies were reported within this research, as the applied load of 330 N was tested with three angulations: vertical, oblique at 45°, and laterally. RESULTS: Linear static stress analysis was performed. The resultant stresses and deformations' distribution patterns did not change with cement type, while the values were altered. All deformations and stresses were found within the normal range. CONCLUSIONS: Analysis results indicated that using stiffer cement material increases tooth structure stresses and reduces crown body stresses and deformations, while bone was nearly insensitive to cement type.

Evaluation of a novel fixed-space maintainer made of light-cured acrylic resin: an in vitro study.

To evaluate a fixed-space maintainer made of light-cure acrylic resin (LCAR) for its flexural and shear bond strength using different bonding systems to the enamel. 45 extracted primary teeth were selected. They were randomly divided into three equal groups (n = 15) along with the type of adhesive system (Tetric Flow, Transbond XT, and Fuji Ortho LC) used for bonding (LCAR) to the tooth surface. Surfaces were treated; LCAR was attached to the treated surfaces using a split Teflon mold. For flexural strength testing, ten bars of LCAR were made using another Teflon-split mold. Shear bond strength and mean flexural strength values were evaluated by a universal testing machine. The highest values of bond strength were recorded for Transbond XT, followed by Tetric Flow, while the lowest values were for Fuji Ortho LC. Various groups had a significant difference as investigated by ANOVA. ARI scores showed no significant difference in debond sites. Mean value and standard deviation of flexural strength for LCAR were 82.83 ± 5.2. LCAR has superior mechanical properties and could be an alternative to currently-in-use space maintainer though in vivo and in vitro trials are needed to progress the ultimate design of LCAR.

Empathy of dental students towards children after behaviour guidance lectures and clinical experience.

INTRODUCTION: The empathetic behaviour of dentists is essential for perfect patient care. Because the behaviour of child patients in a dental clinic differs from that exhibited by the adults, knowing of empathy of dental students towards the child in the dental clinic is an important concern. METHODS: We distributed a modified form of the Health Professions Student version (HPS-version) of the Jefferson Scale of Empathy (JSE) to dental students in two rounds: (R1) before and (R2) after introducing behaviour guidance subcourse and exposure to 3 clinical experiences with children to measure changes in empathy of dental students towards child patients. The modifications include replacing the "patient" words with "child patients" and translation into Arabic. We checked the internal consistency of the modified form of HPS-version by Cronbach's coefficient alpha test. The significance level was set at 0.05 for all statistical analyses. RESULTS: Out of eighty-one, sixty-five dental students completed the survey and attended a behaviour guidance course and three clinical sessions. The questionnaire showed accepted reliability. There was a significant decrease in the empathy of dental students in R2 than R1 (P < .05). The level of empathy for males was less than female students in both rounds (P < .05). CONCLUSIONS: The clinical interaction of children by dental students inhibits their empathy towards child patients, and a specific training course is needed to improve dental students' empathy towards children since learning behaviour guidance may not sufficient.

Mutans streptococci growth on glass ionomer incorporated with chlorhexidine: in-vivo study / Crescimento de Estreptococos mutans em ionômero de vidro incorporado com clorexidina: estudo in vivo

Background: glass ionomer is one of the most frequently used restorative materials for primary teeth restoration. It has been in use for more than 30 years. Their restoration usefulness is preferential compared to other restorations due to their fluoride release and recharge, chemical adhesion to the structure of the dentin and their range of uses. Increasing the antibacterial efficacy of restorative materials is one of the primary goals to decrease the incidence of recurrent caries. Chlorhexidine is the gold standard antibacterial agent in dentistry. Objectives: the objective of this study is to evaluate the antibacterial effect of Chlorhexidine incorporated with glass ionomer on Streptococcus mutans. Methods: Thirty Children between ages ranged 6-9 years old were selected to participate in this study. Children with bilateral caries in lower second primary molars affecting the occlusal and proximal surfaces without pulpitis were included in the study. All cavities were divided into two groups; group (A) restored with Glass Ionomer and group (B) restored with Glass Ionomer Chlorhexidine mixture. The sound proximal surfaces in all cavitated teeth acted as a control. After one month, two months and three months' plaque samples were obtained and Streptococcus mutans counts were calculated. Results: The number of SM taken from sound proximal surfaces for all groups were not changed significantly in whole periods of study. At the all-time interval, the mean log10 of SM in group B was lower than group A and the difference was statistically significant. There is a significant difference in the mean log10 of SM in group B between the 1St month and the 3rd month. Conclusion: The growth of SM was found to be higher in the sound tooth than in GI groups and in GI group was higher than in CHX- GI mixture up to three months (AU)

Antecedentes: o ionômero de vidro é um dos materiais restauradores mais utilizados na restauração de dentes decíduos. É usado há mais de 30 anos. Sua indicação como material restaurador em comparação a outros baseia-se nas propriedades de liberação e recarga de flúor, adesão química à estrutura da dentina e sua variedade de usos. Aumentar a eficácia antibacteriana de materiais restauradores é um dos principais objetivos para diminuir a incidência de cárie recorrente. A clorexidina é o agente antibacteriano padrão-ouro em odontologia. Objetivos: o objetivo deste estudo é avaliar o efeito antibacteriano da Clorexidina incorporada ao ionômero de vidro no Streptococcus mutans (SM). Métodos: Trinta crianças entre 6 e 9 anos foram selecionadas para participar deste estudo. Crianças com cárie bilateral nos segundos molares decíduos inferiores que afetavam as superfícies oclusal e proximal sem pulpite foram incluídas no estudo. Todas as cavidades foram divididas em dois grupos; grupo A, restaurado com Ionômero de Vidro e grupo B, restaurado com mistura de Ionômero de Vidro /Clorhexidina. As superfícies proximais sadias em todos os dentes cavitados atuavam como controle. Após um mês, dois e três meses, foram obtidas amostras de placa e as contagens de Streptococcus mutans foram realizadas. Resultados: O número de SM retirado da superfície proximal sadia para todos os grupos não foi alterado significativamente nos períodos do estudo. No intervalo de todos os tempos, o log10 médio da SM no grupo B foi menor que no A e a diferença foi estatisticamente significante. Há uma diferença significativa no log10 médio da SM no grupo B entre o 1º mês e o 3º mês. Conclusão: O crescimento da SM mostrou-se maior no dente sadio do que nos grupos A; e no grupo A foi maior que no grupo B até três meses.(AU)