Steel drills versus zirconia drills on heat generation at the surgical site of dental implants: A systematic review and meta-analysis.

Objective: The aim was to evaluate the difference in the heat generated between zirconia (Zr) and steel (SS) drills, during implant site preparation. Material and methods: This systematic review followed the PRISMA methodology criteria and used the JBI Critical Assessment Guidelines for Quasi-Experimental Studies for quality assessment. The electronic search was conducted by using the PubMed/MEDLINE, Embase, and Cochrane Library databases to January 2023. The formulated population, intervention, comparison, outcome (PICO) question was "Do zirconia drills generate less heat than steel drills during implant site preparation?". The meta-analysis was based on an inverse variance (IV) method. Results: This review included 10 studies in vitro that used zirconia drills compared to steel drills with or without coatings. The meta-analysis indicated a significant difference between Zr drills and SS drills, with a lower bone temperature variation with Zr drills. Conclusions: Despite the limitations of this review, it was concluded that Zr drills had significantly less temperature variation than SS drills.

Effect of Chlorhexidine and Tea Tree Oil on Reducing the Number of Oral Microorganisms.

OBJECTIVES: Thus, the aim of this study was to compare the effect of using two preoperative mouthwashes (0.12% chlorhexidine and 0.2% tea tree oil) on the number of colonies of oral microorganisms. MATERIALS AND METHODS: Forty participants who needed to be rehabilitated with dental implants were included in this study. They were randomly divided into two groups (chlorhexidine group and tea tree group; n = 20, each). For each group, saliva samples were collected at four different times: T0 (initially)-before using the mouthwash, T1-after 1 minute of using the mouthwash, T10-after 10 minutes of using the mouthwash, and T60-after 60 minutes of using the mouthwash. At T0 and T1, saliva samples were collected before implant placement surgery, and at T10 and T60, saliva samples were collected during surgery. In each group, one saliva sample was collected at each evaluated time point for each patient, totaling 4 saliva collections per patient. MSB agar (Mitis-Salivarius-Bacitracin) and BHI agar (Brain Heart Infusion) culture media were used in each group. Microbial colony counts were performed using a magnifying glass and recorded in CFU (colony forming units)/mL. Statistical analyses were performed using the Friedman, Mann-Whitney U and Wilcoxon tests (p < 0.05). RESULTS: Based on MSB agar culture medium, at T0, the number of Streptococcus mutans colonies in the chlorhexidine group was significantly higher compared with the tea tree group (p <0.05; MSB agar). The chlorhexidine group showed significantly lower CFU/mL values for Streptococcus mutans at T1, T10, and T60 compared with the tea tree group (p <0.05; MSB agar). Based on BHI agar culture medium, at T0, the chlorhexidine group showed a significantly lower value of CFU/mL compared with the tea tree group (p < 0.05; BHI agar). At T1, T10, and T60, the chlorhexidine group showed significantly lower CFU/mL values compared with the tea tree group (p <0.05; BHI agar). CONCLUSION: Chlorhexidine is more indicated as a preoperative mouthwash than tea tree oil, due to its significantly more effective antimicrobial action.

Effects of rehabilitation with complete dentures on bite force and electromyography of jaw and neck muscles and the correlation with occlusal vertical dimension.

OBJECTIVES: The purpose of this study was to assess the effects of oral rehabilitation with complete dentures on bite force and electromyography of the suprahyoid and sternocleidomastoid muscles, and their correlation with occlusal vertical dimension (OVD). The research questions were "What are the effects of rehabilitation with complete dentures on bite force and electromyography of suprahyoid and sternocleidomastoid muscles, and how are they correlated with OVD?" MATERIALS AND METHODS: Patients who are wearers of unsatisfactory removable complete dentures were attended in three sessions (T0, T1, and T2). At T0, while the patients still wore the old dentures, they were submitted to bite force and surface electromyographic exams of the suprahyoid and sternocleidomastoid muscles. These exams were repeated, and the OVD was measured while the patients wore their old and new prostheses, 30 days after insertion of the new prosthesis (T1). The exams were repeated 100 days after the insertion of the new prosthesis (T2). The data were submitted to the Shapiro-Wilk normality test, analysis of variance (ANOVA), and Pearson correlation and linear regression, all with 5% significance. RESULTS: Fifteen patients participated in the study. No statistically significant difference was observed for bite force or electromyography in T0, T1, or T2. However, the correlation and regression tests showed important interactions between the OVD and maximum voluntary occlusal bite force, as well as the OVD and electromyography during deglutition for the suprahyoid muscles. CONCLUSION: Rehabilitation did not impact bite force nor the activity of the assessed muscles (electromyography). On the other hand, OVD was shown to be an important factor for bite force, and deglutition of water after rehabilitation. CLINICAL RELEVANCE: This study shows what are the influences of rehabilitation on oral functions and reinforces the importance of corrected reestablishment of OVD because it has been found to be an important factor for bite force and electromyography during deglutition.

Analysis of Color and Hardness of a Medical Silicone with Extrinsic Pigmentation after Accelerated Aging.

OBJECTIVE: The aim of this study is to evaluate the color alteration and shore A hardness of a medical silicone with extrinsic pigmentation, before and after accelerated aging. MATERIALS AND METHODS: Twenty samples (Silastic Q7-4735) were made with an intrinsic pigmentation. This intrinsic pigmentation was composed of a pink pigment (H-109-P, Factor II) and an opacifier (ZnO). All samples had standardized dimensions (45-mm diameter and 2-mm thickness). Half of the 20 samples manufactured subsequently received an extrinsic pigment (Tan FE-215, Factor II). Therefore, two groups were created (n = 10): Group 1, group with intrinsic pigmentation and without extrinsic pigmentation (control) and Group 2, group with intrinsic and extrinsic pigmentation. Samples were submitted to color and Shore A hardness tests, before and after 1,008 hours of aging. STATISTICAL ANALYSIS: Color alteration data were submitted to Student's t-test (α = 0.05). Shore A hardness data were submitted to two-way analysis of variance and Tukey test (α = 0.05). RESULTS: The incorporation of the extrinsic pigment on the silicone did not affect its color (ΔE) when the two groups were compared (p = 0.232). Regarding the hardness test, the interaction between group and period did not interfere with the hardness results(p=0.599). However, the period factor showed that there was a reduction in the hardness of the silicone after aging (p < 0.05). CONCLUSION: In this study, all the hardness and color results of the silicone used were clinically acceptable, regardless of the presence of extrinsic pigmentation.

Surface Characterization of a Glass Fiber Post after Nonthermal Plasma Treatment with Hexamethyldisiloxane.

PURPOSE: To characterize the surface of glass fiber posts (GFP) after different surface treatments and evaluate which method incorporates higher amounts of silicon (Si) particles, as well as to evaluate the bond strength at the post/ composite-cement interface with four different surface treatments of glass fiber posts luted with composite cement. MATERIALS AND METHODS: Twelve glass fiber posts were obtained from the manufacturer. The posts were randomly distributed into four groups (n = 3): Co (control), no surface treatment; S, 70% alcohol and silane (60 s); HF + S, 10% hydrofluoric acid gel (60 s) and silane (60 s); NTP, nonthermal plasma of hexamethyldisiloxane (HMDSO) associated with argon (30 min). The surface of each GFP was characterized through scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Forty GFPs were randomly divided into 4 groups according the surface treatments (n = 10) and cemented with one composite cement (Rely X U200) into artificial canine teeth. The specimens were placed in a universal testing machine and subjected to tensile testing until failure occurred. Statistical analysis of the atomic percentage and bond strength was performed using ANOVA, followed by the post-hoc Tukey test (p = 0.05). RESULTS: EDS graphics showed that the NTP group had a higher Si atomic percentage (at%) than the other groups (p < 0.001). The HF + S group had a higher Si at% than did the Co and S groups. SEM images illustrated that the surfaces of the GFPs were variously modified after different treatments. The NTP group incorporated higher Si levels on the GFP surface and yielded the highest bond strengths (p < 0.005) compared to the other tested groups. CONCLUSION: Treatment with HMDSO + Ar plasma (NTP) incorporated higher Si levels on the surface of the GFPs without inducing critical defects. NTP treatment promoted better bond strength results when compared to the other tested group when GFPs were cemented with composite cement.

Photoelastic stress analysis in prosthetic implants of different diameters: mini, narrow, standard or wide.

PURPOSE: This study investigated the biomechanical behavior of screwed partial fixed prosthesis supported by implants with different diameters (2.5 mm; 3.3 mm and 3.75 mm) by using a photoelastic analysis. MATERIALS AND METHODS: Six photoelastic models were fabricated in PL-2 resin as single crowns or splinted 3-unit piece. Models were positioned in a circular polariscope and 100-N axial and oblique (45 degrees) loads were applied in the occlusal surface of the crowns by using a universal testing machine (EMIC). The stresses were photographically recorded and qualitatively analyzed using a software (Adobe Photoshop). RESULTS: Under axial loading, the number of fringes was inversely proportional to the diameter of the implants in the single crown models. In the splinted 3-unit piece, the 3.75-mm implant promoted lower number of fringes regardless of loading area application. Under oblique loading, a slight increase of fringes number was observed for all groups. CONCLUSION: The standard implant diameter promoted better stress distribution than the narrow and mini diameter implants. Additionally, the splinted crowns showed a more uniform stress distribution.

Stress distribution in implant-supported prosthesis with external and internal implant-abutment connections.

OBJECTIVE: This study aimed to investigate the stress distribution in screwed implant-supported prostheses with different implant-abutment connections by using a photoelastic analysis. MATERIALS AND METHODS: Four photoelastic models were fabricated in PL-2 resin and divided according to the implant-abutment connection (external hexagon (EH) and Morse taper (MT) implants (3.75 × 11.5 mm)) and the number crowns (single and 3-unit piece). Models were positioned in a circular polariscope and 100-N axial and oblique (45) loading were applied in the occlusal surface of the crowns by using a universal testing machine. The stresses were photographically recorded and qualitatively analyzed using software (Adobe Photoshop). RESULTS: Under axial loading, the MT implants exhibited a lower number of fringes for single-unit crowns than EH implants, whereas for a 3-unit piece the MT implants showed a higher number of fringes vs EH implants. The oblique loading increased the number of fringes for all groups. CONCLUSION: In conclusion, the MT implant-abutment connection reduced the amount of stress in single-unit crowns, for 3-unit piece crowns the amount of stress was lower using an external hexagon connection. The stress pattern was similar for all groups. Oblique loading promoted a higher stress concentration than axial loading.

Color stability of maxillofacial silicone with nanoparticle pigment and opacifier submitted to disinfection and artificial aging.

The purpose of this study was to evaluate the color stability of a maxillofacial elastomer with the addition of a nanoparticle pigment and∕or an opacifier submitted to chemical disinfection and artificial aging. Specimens were divided into four groups (n = 30): group I: silicone without pigment or opacifier, group II: ceramic powder pigment, group III: Barium sulfate (BaSO(4)) opacifier, and group IV: ceramic powder and BaSO(4) opacifier. Specimens of each group (n = 10) were disinfected with effervescent tablets, neutral soap, or 4% chlorhexidine gluconate. Disinfection was done three times a week during two months. Afterward, specimens were submitted to different periods of artificial aging. Color evaluation was initially done, after 60 days (disinfection period) and after 252, 504, and 1008 h of artificial aging with aid of a reflection spectrophotometer. Data were analyzed by three-way ANOVA and Tukey test (α = 0.05). The isolated factor disinfection did not statistically influence the values of color stability among groups. The association between pigment and BaSO(4) opacifier (GIV) was more stable in relationship to color change (△E). All values of △E obtained, independent of the disinfectant and the period of artificial aging, were considered acceptable in agreement with the norms presented in literature.

Evaluación de la dureza shore a en dos técnicas de impresión con siliconas por condensación bajo la influencia del uso de desinfección química por impresión con solución de clorhexidina al 2 por ciento / Evaluation of hardness in two impression techniques with condensation silicones under influence chemical disinfection with clorhexidine 2 percent

Las siliconas de polimerización por condensación, actualmente, son muy utilizadas en el mercado odontológico. Debido a este hecho, nuestro objetivo fue estudiar la dureza Shore A de dos siliconas de condensación (Zetaplus - Zhermark y Clonage - DFL), simulando dos técnicas de impresión (densa y densa + fluida) bajo la influencia de desinfección química con solución a base de clorhexidina al 2 por ciento (aspersión por 5 minutos). Fueron confeccionados 56 muestras, a partir de matrices metálicas, divididos en 4 grupos para cada técnica de impresión, siendo la mitad de las muestras de cada técnica sometidas a desinfección química. El Test de dureza fue realizada por medio de un durómetro (modelo GSD 709) de acuerdo con las especificaciones D-2240 de la Sociedad Americana para Prueba y Materiales (ASTM), los resultados obtenidos, fueron analizados por medio del Test de análisis de varianza y al Test de Tukey (p<0,05). Se concluyó, que para cualquier condición experimental estudiada se encontró diferencia estadísticamente significativa cuando se analizaron los valores medios de desinfección química, tipo de material y técnica utilizada

Elastomerics materials currently represent a major choice in the dental market as an impression material. The aim of this study was to asses Shore A hardness of two condensation silicones (Zetaplus - Zhermack and Clonage - DFL) using two impression techniques (putty and putty/wash) under influence of chemical disinfection with clorhexidine spray to 2 percent (for five minutes). Fifty-six specimens were made in metallic matrices, subdivided in 4 groups for each impression technique; half of each technique was submitted to chemical disinfection. Hardness test was performed with a durometer (GSD 709) according ASTM specifications (D-2240), the results were submitted to analyses of variance (ANOVA) and Tukey’s test (p<0.05). It was concluded that for all experimental condition, difference statistically significant was found

Lengua Protética Articulada para Paciente Glosectomizado

Patients with oral carcinoma are submitted the surgical excision of the tongue, with or without resection of floor of the mouth or of the bone of the mandible. Prosthodontic rehabilitation for patient submitted the total glossectomy is describe, using lingual prosthesis in silicone adapted in total denture mandible. One lingual prosthesis was fabricated objectifying to recover functions disrupted: speech, mastication and swallowing. Through prosthetic treatment, articulation is improved, food is more easily directed into the esophagus, tissues are protected and socialization is enhanced.

Pacientes con carcinoma bucal quienes deben someterse a remoción quirúrgica de la lengua, con o sin resección del piso bucal o del hueso mandibular. Se describe la rehabilitación protética de pacientes que se sujetan a oclusión total de la lengua, utilizando lengua protética en silicón adaptada a la prótesis total o inferior. Una lengua protética fue confeccionada, con la finalidad restablecer funciones comprometidas: el hablar, masticación y deglución. Por el tratamiento protético, la articulación es optimizada, el alimento es conducido para el esófago más fácilmente, los tejidos son protegidos y la socialización es intensificada.

Pacientes com carcinoma bucal freqüentemente são submetidos à remoção cirúrgica da língua, com ou sem ressecção do assoalho bucal ou do osso mandibular. Reabilitação protética de paciente submetido a glossectomia total é descrita, utilizando língua protética em silicone adaptada à prótese total inferior. Uma língua protética foi confeccionada, a fim de restabelecer funções comprometidas: fala, mastigação e deglutição. Através do tratamento protético, a articulação é melhorada, o alimento é direcionado ao esôfago mais facilmente, os tecidos são protegidos e a socialização é intensificada.