Evaluation of the Sealing Ability of Direct versus Direct-Indirect Veneer Techniques: An In Vitro Study

Backgrounds. Marginal discoloration, microleakage, wear, and marginal fractures are all prevalent problems with composite veneers, and this scenario leads the esthetic outcome to deteriorate with time, resulting in patient discontent. Aim of the Study. The study’s goal was to determine the marginal sealing ability of composite laminate veneers when employing two types of veneer techniques: direct and direct-indirect veneers, as well as two types of composite resin: nanohybrid and microfilled composite resin restorations, using dye penetration method. Materials and Methods. In this study, forty extracted human teeth were utilized. Following a standardized veneer preparation on the labial surface of the teeth, they were separated into two groups of 20 teeth each, using the following composite application techniques: group A: direct veneers and group B: direct-indirect veneers. Following that, each major group was separated into two subgroups of ten teeth each, based on the type of composite employed: subgroup 1 used nanohybrid composite resin, while subgroup 2 used microfilled composite resin. All of the samples were kept in distilled water, thermocycled, and soaked in 2% basic fuchsine dye. These specimens were sectioned and examined under a stereomicroscope for dye penetration at the gingival margin. The data was analyzed using independent T -tests using SPSS 22. Result. Using direct-indirect veneer technique with nanohybrid composite resin material resulted in the most negligible dye penetration at the gingival margin, while using direct veneer technique with microfilled composite resin material resulted in the maximum dye penetration. For both composite materials, gingival microleakage was lower when using the direct-indirect veneer technique than when using the direct technique, and the difference was statistically significant ( P < 0.05 ). In both techniques, gingival microleakage was lower with nanohybrid composite than with microfilled composite, and the difference was statistically highly significant ( P = 0.001 ). Conclusion. The sealing ability of the gingival margin of tooth/composite interface is better when applying direct-indirect veneer technique with nanohybrid composite resin than that of direct veneer technique with microfilled composite resin material.

Esthetic-functional reconstruction of posterior teeth with direct restorations (a case report)

Teeth restoration in respect with anatomy and function with direct composite restoration does not lose its relevance for many years. The driving factor for the widespread use of direct restorations is satisfactory aesthetic results, simplicity and high speed of their implementation, and relatively low cost. Moreover, dental restorations in direct technique are constantly being improved due to the unprecedented growth of technologies in the production of dental materials and equipment, which are now living their golden age. This article presents a clinical case of replacing old incompetent fillings with impaired marginal fit of the posterior teeth with highly aesthetic and functional composite restorations.

Modeling and analysis of 3D radiative heat transfer in combustor

Compared with wall emission, gas thermal radiation is much more complicated because of its nongray and volumetric property. In this paper, a numerical method is established to calculate 3D radiative heat transfer in combustor by modelling radiative transfer as well as nongray radiative properties of combustion gases. Energy exchanges caused by thermal radiation and conduction are calculated and compared in a rectangular combustor, which shows the significant role of thermal radiation in heating fuel-air mixtures and prompting internal combustion reactions. Besides, radiative heat flux on the wall is also quite obvious although a non-contacting flow case, revealing the special challenges for thermal protections brought by radiant energy. Lastly, increasing the working pressure means much more participating species in radiative transfer process and the radiative effects will be also magnified. The numerical method in this paper provides a direct technique to analyze the role of thermal radiation in complex thermochemical reactions while the application case proves the necessity of coupling a high-accuracy radiation model when simulating combustion and flame propagation.

Restorative Treatment of Amelogenesis Imperfecta with Prefabricated Composite Veneers

This case report presents the use of prefabricated composite veneers for restorative treatment of amelogenesis imperfecta (AI). This technique bridges the gap between a conventional direct technique and a conventional indirect technique and introduces an alternative semidirect restorative technique for AI patients. The aim of this case report is to describe restoration of a young girl with severe AI using prefabricated composite veneers and to discuss the benefits and limitations of this technique compared to the alternative restorative techniques.

Development of experimental vibro-acoustic transfer function for a system with combined rolling-sliding motion

Combined rolling-sliding contact is present in popular non-linear systems such as cam-follower, gears, clutches, and brakes. These systems produce significant noise due to complex contact between the components during operation. The noise generated is a strong function of the contact parameters and excitation to the system. The objective of this study is to develop a transfer function to quantify the vibro-acoustic noise for various contact conditions. Acceleration, reaction forces, and acoustic pressure measurements are made on a cam-follower setup with combined rolling-sliding contact. Experiments are performed under different conditions of friction, lubrication, load, and speed. Contact forces are back-calculated using the kinematics. The transfer function relating the acoustic pressure to different forces is estimated. It is observed that the contact parameters govern the transfer function and hence the vibro-acoustic systems. The developed transfer function is useful in designing better sub-systems with combined rolling-sliding contact to reduce noise exposure, as a direct technique to relate the contact parameters to the noise does not exist. This study can be extended to other complex systems such as gears and clutches.

Life course socioeconomic position and body composition in adulthood: a systematic review and narrative synthesis

Introduction Multiple systematic reviews have investigated the relation between socioeconomic position (SEP) and body mass index (BMI) throughout the life course. However, BMI does not capture quantity and distribution of fat and muscle, which are better indicators of obesity than BMI, and have been independently linked to adverse health outcomes. Less is known about the relation between SEP and body composition, and the literature has not been reviewed. We therefore systematically reviewed the literature on the association between life course SEP and body composition in adulthood. Methods A protocol was registered on PROSPERO (CRD42019119937), and the review followed PRISMA guidelines. An electronic search of three databases (MEDLINE, Embase Classic + Embase and SPORTDiscus) was conducted. Original studies in the English language were included that examine the association between any recognised measure of SEP at any age and body composition (fat mass, fat-free mass, ratio and distribution) in adulthood, measured using a direct technique, i.e., not an anthropometric measure. A narrative synthesis was conducted. Results A total of 47 papers were included in the final review, none were from low-income countries (LICs). Greater advantage in childhood and adulthood was associated with lower fat levels in high-income countries (HICs). Associations in the opposite direction were found exclusively in middle-income countries (MICs). No studies in MICs reported associations for childhood SEP. For measures of lean mass, the majority of papers reported no association, or greater advantage in adulthood associated with higher lean mass, with little variation between HICs and MICs. Associations in HICs are more often observed in women than men. Conclusion The results indicate that fat measures follow similar patterns to those seen for BMI, and that women in HICs are more likely to experience inequalities in both fat and lean measures. Further research in LICs and MICs is needed.

Direct-Indirect Technique Restoration for Non-Carious Cervical Lesions Treatment: a Case Report

Non-Carious Cervical Lesions are characterized by slow and progressive loss of hard tissue at the level of enamel-cement junction, without bacterial involvement. This work aimed to address a case report of restorative treatment in Class V cavities in multiple premolars using the direct-indirect technique with composite resin. A 42 year-old male patient presented for esthetic restorative treatment with the complaint of severe dentin hypersensitivity and wedged-shaped non-carious cervical lesions affecting the maxillary premolars. The restorative treatment chosen was a direct-indirect technique with composite performed into three sessions as follows: making the class V composite inlays, cementation, and final polishing. The direct-indirect technique as an alternative to the traditional direct technique has the benefits of a better contour of the restoration, since the finishing and polishing are made extraorally. Besides, the control of the polymerization stress and less discomfort to the patient are other advantages. In the case of direct-indirect class V restoration, the advantages far surpass those of the direct technique. Keywords: Hypersensitivity. Tooth Wear. Composites Resins ResumoAs Lesões Cervicais Não Cariosas se caracterizam pela perda lenta e progressiva de tecido duro próximo a junção cemento-esmalte, sem envolvimento bacteriano. Este trabalho tem o objetivo de relatar um caso clínico de tratamento restaurador em cavidades do tipo Classe V em pré-molares pela técnica direta-indireta com resina composta. Paciente do sexo masculino, 42 anos, queixava-se de forte sensibilidade e múltiplas Lesões Cervicais Não Cariosas na forma de cunha nos pré-molares superiores. O tratamento restaurador escolhido foi a técnica direta-indireta com resina composta realizado em três sessões distribuídas em confecção da peça em resina composta, cimentação e polimento final. A técnica direta-indireta surge como alternativa a técnica direta tradicional trazendo como benefícios um melhor contorno da restauração, uma vez que esta é acabada e polida fora da boca, além do controle do estresse de polimerização e menor desconforto ao paciente. A intervenção restauradora direta-indireta se mostra eficaz devido ao fato de conseguir contornar dificuldades encontradas em técnicas restauradoras diretas. Palavras-chave: Hipersensibilidade. Desgaste dos Dentes. Resinas Compostas

EXPERIMENTAL STUDY OF EXOTERMIC EFFECTS INSIDE DENTAL PULP CHAMBER WHEN APPLYING DIRECT TECHNIQUE OF MANUFACTURING TEMPORARY CROWN

The aim of this study is to determine the optimal combination of self-curing resins and type of matrix that provides a minimal temperature increase in the pulp chamber during the fabrication of temporary crowns. Material and methods. We designed as experimental model of direct temporary crown fabrication for extracted and than prepared molars. Intrapulpal temperature rise was measured in vitro conditions during polymerization of Protemp II (3M), Protemp 4 (3M), Visalis Temp (Kettenbach), Structur (Voco) and Carbodent (Stoma). Output and peak temperature findings of self-curing resin polymerization were recorded and values ​​of temperature increase in the tooth chamber were calculated. Two types of materials were used to make external anatomical moulds: 1) silicone impression material Panasil Putty Soft of high and low viscosity and Panasil initial contact Light (Kettenbach) to make two-phase impression; 2) transparent thermoplastic polymer Erkodur (Erkodent), sheet of 1.0 mm thick, vacuum pressed. Results and Discussion. We obtained the following finding of the temperature rise inside the pulp chamber (polymer pattern / silicone matrix): Protemp IV (2,2˚C / 0,2˚C), VisalisTemp (3˚C / 0.3˚C), Protemp II (3,3˚C / 0,5˚C), Structur (3,4˚С/0,6˚С), Karbodent (6.7˚C / 3.0˚C). Conclusions. Exothermic effects during intra oral fabrication of temporary crowns can be minimized by polymerization of resins in the silicone mould as this material can absorb and dissipate heat.

A Technique to Fabricate a New Crown to an Existing Removable Partial Denture

Fabricating a crown for a tooth that serves as an abutment for an existing removable partial denture (RPD) provides a restorative challenge. Typically, the compromised tooth requiring an extra-coronal restoration is initially restored. It is followed by the construction of a new RPD that accurately fits the restored abutment. An increasingly common scenario is that the existing RPD is deemed clinically acceptable and, therefore, does not require replacing. This results in the clinical dilemma of fabricating a crown for an abutment tooth, while also considering how the contours of this restoration will fit with the RPD’s clasps and rests. This can be achieved through the use of various techniques subdivided into indirect, direct and combined indirect-direct. This article describes an indirect-direct technique used in conjunction with the functionally generated path technique to achieve accurately a stable record of the patient’s occlusion in the fabrication of a new crown to an existing RPD.