Evaluation of Microstrain in the Regions Surrounding Morse Taper and External Hexagon Implants.

OBJECTIVE: The aim of this study was to compare the Morse taper (MT) + titanium base (Ti-Base) abutment with the external hexagon (EH) + Ti-Base abutment by using the strain gauge method in the mesial, distal, and apical-buccal areas around these types of implants. MATERIALS AND METHODS: This study investigated two groups, MT and EH, each comprising five polyurethane samples with a dental implant in the area of artificial tooth 15 (3.75 × 11.5 mm) of a dental manikin. The strain gauges were glued to the mesial, distal, and apical-buccal polyurethane areas of all samples in relation to the implant. Ti-Base nonangled abutments measuring 5.0 × 4.7 × 1.0 mm (DSP, Brazil) were installed on the implants in each group. Ten identical zirconia crowns were constructed by scanning and milling and were subsequently cemented onto the Ti-base abutments with calcium hydroxide cement. Then, an axial load of 100 N was applied to the occlusal region of the zirconia crowns, and strain gauge measurements were taken. STATISTICAL ANALYSIS: Strain gauge data were assessed by a two-way analysis of variance (ANOVA) with "implant connection" and "strain gauge position" factors, followed by the Bonferroni test (p < 0.05). RESULTS: The MT group exhibited a statistically significant reduction in microstrain in the mesial and apical strain gauge measurements compared to the EH group. CONCLUSION: The MT group exhibited less microstrain in the mesial and apical areas of the polyurethane samples near the implant. Consequently, the MT connection was considered more biomechanically advantageous.

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.

Abutment on Titanium-Base Hybrid Implant: A Literature Review.

An increase in the use of Computer-Aided Design (CAD) and Computer-Aided Manufacturing (CAM) technologies challenges the conventional prosthetic fabrication procedures that are practical and centered on a digital workflow for the patient, especially for dental implants. Increasing workflow of digital restoration work, considering computer-used CAM for restoration technology systems and also fast/CAM for building restoration technology; fast/CAD, also known as abut-Base, has increased interest. Studies on adaptation of different restorative materials, on titanium (Ti)-base abutments, traction, and transformed cycling have become relevant. The objective of this work was to research, through literature studies, on restoration-type abutments. A total of 24 articles were found after searching the following terms in PubMed/Medline, Scopus, and Embase databases: "ti-base AND abutment." Twenty-one manuscripts selected from the inclusion and exclusion criteria. After an analysis of these articles, it was concluded that the Ti-base abutment and components from the same manufacturer as the Implant should be used preferably; milled monolithic crowns designed to adapt to the Ti-base the hybrid abutment-crown assembly does not affect torque maintenance after thermal aging; the saliva and cleaning protocol of the Ti-base bonding surfaces can influence the operations of the Ti-base crowns; Ti-base and Crown surface treatment is recommended for better applicability and stability results, and the superiority of resin-based cements compared with other types of cements.

Comparison of Techniques for Obtaining Centric Relation Based on the Reproducibility of the Condylar Positions in Centric Relation-A Systematic Review.

The objective of this systematic review was to compare centric relation (CR) techniques that belong to the same method of obtaining CR (guided, graphical, or physiological method), to verify which CR technique within each method of obtaining CR generates the greatest reproducibility of the condylar positions (or mandibular position) in CR. The PubMed, Cochrane Library, SciELO, Scopus, and Web of Science databases were searched for articles published up to May 5, 2021. The search terms were combinations of "dental centric relation" (MeSH), with each of the following terms (individually): "reproducibility of findings" (MeSH); "jaw relation record" (MeSH); "chin point"; "gothic arch"; "bimanual manipulation"; "swallowing" (MeSH); and "jig." Inclusion criteria: clinical studies in English; individuals without temporomandibular dysfunction and with complete or almost complete dentition or complete edentulous; and comparison between CR techniques belonging to the same method of obtaining CR based on the reproducibility of condylar positions in CR. For each method of obtaining the CR, the following CR techniques were considered: guided method (chin point guidance and bimanual manipulation); graphic method (intraoral and extraoral gothic arch tracing); and physiologic method (swallowing and tongue retrusion along the palate). A total of 1692 articles were screened. After the inclusion and exclusion criteria were applied, six articles were included in this review. None of the included studies evaluated edentulous individuals. All included articles compared CR techniques of the guided method. Three articles concluded that the bimanual technique showed greater reproducibility of the condylar positions in CR than the chin point guidance technique, two articles showed equivalence between these techniques, and 1 article concluded that the chin point guidance technique showed greater reproducibility of the condylar positions in CR than the bimanual technique. Thus, in this systematic review, the bimanual technique was often superior (generated greater reproducibility of the CR) or at least equivalent to the chin point guidance technique. Therefore, for individuals with complete dentition and without temporomandibular disorders, the bimanual technique is more recommended.

Quality of Life, Satisfaction, Occlusal Force, and Halitosis after Direct and Indirect Relining of Inferior Complete Dentures.

OBJECTIVE: The aim of this study was to compare the direct relining technique with the indirect relining technique in relation to quality of life, satisfaction with the relining, occlusal force, and halitosis of users of acrylic complete dentures. MATERIALS AND METHODS: Twenty bimaxillary edentulous individuals were selected. They had to use the same pair of complete dentures for a minimum of 1 year and a maximum of 5 years. The subjects were randomly divided in groups of direct relining and indirect relining of the inferior denture (n = 10). Both groups received the same silicone-based relining. The clinical tests verified the quality of life (Oral Health Impact Profile in edentulous individuals), the satisfaction with the relining, the occlusal force, and halitosis. The tests (halitosis and occlusal force) were performed initially (before the relining), immediately after the relining, and 30, 60, 90, and 180 days after the relining. The questionnaires (quality of life and satisfaction with the relining) were performed initially (before the relining), and 30, 60, 90, and 180 days after the relining. STATISTICAL ANALYSIS: Analysis of variance and the Tukey test were used (p < 0.05). RESULTS: There was no statistical difference comparing the two techniques in all the evaluations (p < 0.05). There was a significant statistical difference for the factor of time in all clinical tests for each relining technique (p < 0.05). The quality of life and satisfaction with the relining increased significantly 30 days after the relining when compared with the initial time point, for both techniques (p < 0.05). The occlusal force increased significantly after 90 and 180 days when compared with the initial time point, for both techniques (p < 0.05). Halitosis decreased significantly immediately after the relining when compared with the initial time point, for both techniques (p < 0.05). CONCLUSION: Independent of the relining technique used, there was an increase in the quality of life, satisfaction with the relining, and occlusal force, as well as a reduction in the level of halitosis. Both techniques generated similar results and therefore can be options in clinical practice.

Dentistry and Intensive Care Unit: A Brief Report.

OBJECTIVE: The aim of this study is to verify whether removable dentures of patients admitted to an intensive care unit (ICU) are niches of microorganisms that can cause pathologies (Staphylococcus aureus, Candida spp., and enterobacteria). MATERIALS AND METHODS: Fifteen patients who were denture wearers (removable partial denture and complete denture) were included in this study. Patients must wear their dentures daily, and these dentures must have acrylic parts. Microbial biofilm was collected from the acrylic part of one denture of each patient. Then, the biofilm was seeded on different culture media: Sabouraud agar, blood agar, MacConkey agar, and mannitol salt agar. In this study, biochemical evaluations of microorganisms were performed. STATISTICAL ANALYSIS: The percentage of dentures with the microorganism identified by each culture medium was calculated. RESULTS: In total, 100% of the dentures were positive for Staphylococcus spp. (blood agar) and Candida spp. (Sabouraud agar); 33.3% of the dentures were positive for S. aureus (Mannitol salt agar); and 13.3% of the dentures were positive for Shigella spp. (MacConkey agar). CONCLUSION: Removable dentures of patients (removable partial dentures and complete dentures) admitted to an ICU are niches of microorganisms that can cause pathologies.