Comparative analysis of optical microscopy, scanning electron microscopy, and micro-computed tomography on measurements

Abstract: Microscopic measurements are widely used in scientific research and the correct equipment to perform these evaluations could be critical to determine study results. Regarding microscopic measurements, three of the most used methods are: Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and Micro-computed Tomography (MCT). It is important to select the best method for assessing diverse parameters, considering operational characteristics of the method, the equipment efficiency, and the machinery cost. Aim: Therefore, the main objective of this study was to define which is the most useful measurement method for assessing magnitudes below 0.4 mm. Methods: Ten dental implants, with known dimensions as defined by the manufacturer were randomly distributed. Two blinded observers assessed the distance between the second and the third screw vortex of the implants using three suggested methods. The true distance was defined to be 0.5 mm. Results: The assessed distances were: 0.597±0.007mm for OM, 0.578±0.017mm for SEM, and 0.613±0.006mm for MCT. The assessed distances were significantly different when the methods were compared (P>0.01). All measurements were into the CAD tolerances. Conclusion: It was possible to conclude that linear easurements between 595 and 605 µm could be performed by any of the described technologies (AU)

Avaliação da eficiência antibacteriana de géis e pomadas utilizados no interior de implantes / Assessment of the efficiency of antibacterial gels and ointments used inside dental implants

Diversas substâncias antibacterianas são utilizadas nos parafusos dos componentes sobre implantes para prevenir a proliferação bacteriana no interior destes e a microinfiltração bacteriana. Este estudo tem como objetivo comparar a eficiência de diversas concentrações dos géis de clorexidina (1%, 2% e 2,5%) e tetraciclina (1%, 2% e 2,5%) e a pomada Neosporin, antibacterianos utilizados no interior de implantes. A eficiência antibacteriana foi determinada pelas zonas de inibição obtidas por meio do método de difusão em ágar, em placas previamente semeadas com Escherichia coli (ATCC 35218). O diâmetro da inibição antibacteriana foi mensurado (mm) e estatisticamente analisado (One-way ANOVA, α = 0.05). De acordo com os resultados deste estudo, os géis de tetraciclina 1%, 2% e 2,5% apresentaram maior halo inibitório, sendo estatisticamente significante, com médias de halos de 14,8 mm, 15,4 mm e 15,3 mm, respectivamente, enquanto que os géis de clorexidina 1%, 2% e 2,5% apresentaram médias de halos de 6,31 mm, 6,31 mm e 6,36 mm; a pomada de Neosporin® apresentou halo, com média de 3,28 mm, sendo os menores halos de inibição. Pode-se concluir que os géis de tetraciclina apresentam maior eficiência na atividade antibacteriana, sendo, dentre os materiais testados, o gel de tetraciclina a 1% o mais indicado para ser utilizado por não apresentar diferenças significantes em relação a outras concentrações desta substância (AU).

To prevent bacterial microleakage and growth, several antibacterial substances are randomly used inside dental implants. This study aimed to compare the efficiency of three antibacterial substances in different concentrations, used inside implants: chlorhexidine gel (1%, 2% and 2.5%) and tetracycline gel (1%, 2% and 2.5%) and Neosporin ointment. Antibacterial efficiency was determined by the diameter of inhibition zones obtained through agar diffusion method on plates previously seeded with Escherichia coli (ATCC 35218). The diameter of the antibacterial inhibition was measured (mm) and submitted to statistical analysis (One-way ANOVA, α= 0.05). According to the results of this study, statistically significant differences were observed among the substances. Tetracycline gels have presented the largest growth inhibition zones with means of 14.8 mm (1%)15.4 mm (2%) and 15.3 mm (2.5%), while chlorhexidine gel had mean zones of 6.31 mm (1%), 6.31 mm (2%) and 6.36 mm (2.5%); Neosporin® ointment had the lower zones with an average of 3.28 mm. It can be concluded that tetracycline gels are more effective against the antibacterial activity (AU).

Fracture Resistance of Internal Conical and External Hexagon: Regular and Narrow Implant-Abutment Assemblies.

PURPOSE: The aim of this study was to compare the maximum load on the elastic limit of internal conical (IC) implants with regular external hexagon (REH) and narrow external hexagon (NEH) implants. MATERIALS AND METHODS: Thirty cylindrical implants were divided in 3 groups (n = 10): REH (3.75 mm); NEH (3.3 mm); IC (3.5 mm). The implants were evaluated by means of cantilever bending loads using a mechanical testing machine. A strain qualitative analysis and the corresponding angles were analyzed. Using single factor analysis of variance with Tukey Test and Friedman Test (P < 0.05) the statistical analysis for data were performed. RESULTS: REH (294.37 N) and IC (294.37 N) groups presented statistically greater Fle than NEH (189.16 N). Regarding to the strain, there were no significant differences among groups. However, there were a greater number of fissures and more fractures present on NEH group. CONCLUSION: The IC implant with smaller diameter did not result in reduction of elastic limit when compared with the REH implants. Nevertheless, the reduction of 0.45 mm of the hexagonal connection implant's diameter has significantly diminished the elastic limit.

A conservative approach to retrieve a fractured abutment screw - Case report.

INTRODUCTION: Regarding implant-supported prostheses, the most reported types of complications are related to loosening or fracturing of abutment or prosthesis screws. This case report shows a series of procedures that allowed a conservative solution for a fractured screw. It avoided removing the implant and also allowed the same prosthesis to be used after guided-drilling the fractured screw and re-tapping the implant internal threads. The same prosthesis was replaced immediately after the procedure. PATIENT: A 67-year-old male patient, who had a fractured abutment screw of the lower left first molar implant. The patient decided for the conservative treatment option and an attempt was made to remove the fractured screw. DISCUSSION: Parafunctional habits can generate excessive occlusal forces, which are risk factors associated with loosening and fracturing implant screws and even the fixtures themselves. This case report focus on the probable causes, difficulties and risks associated with this procedure and it also discusses the alternative approaches. CONCLUSION: The purposed treatment allowed a time and money saving resolution for fractured abutment screws.

Substituição e estética imediata na região anterior da maxila utilizando implante Drive e munhão anatômico / Replacement and immediate aesthetic in the anterior maxilla using Drive implants and anatomic trunnion

O aumento da exigência estética na reabilitação com implantes provocou uma mudança nos conceitos de tratamento dentro da Implantodontia. Novas técnicas vêm sendo desenvolvidas no intuito de diminuir o tempo de tratamento, minimizando também o custo e o trauma cirúrgico e psicológico dos pacientes, principalmente em regiões com envolvimento estético. A substituição imediata em Implantodontia consiste na instalação de implantes em alvéolos frescos imediatamente após a extração dentária e a confecção de um provisório diretamente sobre implante, na mesma sessão clínica. Isto é possível quando é alcançada uma estabilidade primária suficiente para que este implante seja submetido a cargas funcionais controladas. A técnica de substituição e estética imediata é um procedimento que oferece elevados índices de sucesso, uma vez que permite a diminuição do tempo de espera pela prótese definitiva, menor número de intervenções cirúrgicas, eliminação da utilização de prótese provisória re¬movível ou adesiva e favorece a manutenção dos tecidos peri-implantares, além de oferecer um relativo conforto psicológico ao paciente. O objetivo deste trabalho é relatar um caso clínico de substituição e estética imediata de um incisivo central superior fraturado, discutindo as vantagens desta técnica.

The demand for aesthetic results in reatment with dental implants has increased resulting on a change in Implantology. New techniques were developed in order to reduce the time of treatment minimizing costs, surgical and psychological trauma to the patients, especially in regions with aesthetic involvement. Immediate replacement consists on installing implants in fresh alveolus immediately after tooth extraction and preparation of a provisional crown directly over the implant, all in the same clinical session. This is possible when achieved enough primary stability is achieved, so the implant is subjected to controlled functional loads. The replacement and immediate aesthetics technique has a high success rate, since it allows re¬duction on the waiting time for definitive prosthesis, smaller number of surgeries, elimination of use of adhesive or removable prosthesis, assists the preservation of peri-implant tissues, besides offering elative psychological comfort to the patient. The objective of this study was to report a case of immediate replacement of a fractured maxillary central incisor, discussing the advantages of this technique.

Bacterial microleakage at the implant-abutment interface in Morse taper implants

AIM: To evaluate the microleakage at the implant-abutment (I-A) interface of Morse tapered implants inoculated with different volumes of bacterial suspension. METHODS: Morse tapered I-A sets were selected and divided in two groups depending on the type of abutment: passing screw (PS) and solid (S), and then subdivided into four subgroups (n=6) according to the suspension volume: PS1: 0.1 µL; PS3: 0.3 µL; PS5: 0.5 µL; PS7: 0.7 µL; S1: 0.1 µL; S3: 0.>3 µL; S5: 0.5 µL and S7: 0.7 µL. A control test was performed to verify the presence of external contamination during the inoculation and the implants were incubated for microbiological analysis. The microleakage was evaluated every 24 h for 7 days by the clarity of solution. After this period, the implants were disassembled for confirmation of bacterial viability. RESULTS: All the specimens with 0.7 µL and one sample of S5 presented turbidity in the control test indicating external contamination, and were excluded from the study. After 7 days of observation, none of the specimens presented positive results for microleakage and the bacterial viability was confirmed in all specimens. The 0.1 µL and 0.3 µL volumes did not present bacterial microleakage, meaning that these volumes may be inadequate for analysis. CONCLUSIONS: None of the sets evaluated showed bacterial microleakage at the I-A interface and the volume of 0.7 µL exceeded the internal capacity of the implants...

Micro-leakage at the implant-abutment interface with different tightening torques in vitro.

OBJECTIVES: This study evaluated the microleakage at the implant/abutment interface of external hexagon (eH) implants and abutments with different amounts of bacteria and tightening torques. MATERIAL AND METHODS: A bacterial suspension was prepared to inoculate the implants. The first phase of this study used nine EH implants and abutments that were divided into three groups with different amounts of bacterial suspension (n=3): V0.5: 0.5 µL; V1.0: 1.0 µL e V1.5: 1.5 µL, and tightened to the manufacturer's recommended torque. The second phase of this experiment used 27 assemblies that were similar to those used in the first phase. These samples were inoculated with 0.5 µL of bacterial suspension and divided into three groups (n=9). T10: 10 Ncm; T20: 20 Ncm and T32: 32 Ncm. The samples were evaluated according to the turbidity of the broth every 24 hours for 14 days, and the bacteria viability was tested after that period. The statistical evaluation was conducted by Kruskal-Wallis testing (p<.05). RESULTS: During the first phase, groups V1.0 and V1.5 was presented with bacterial contamination in all samples after 24 h. During the second phase, two samples from group T10 and one from T20 presented positive results for bacterial contamination. Different amounts of bacterial solution led to overflow and contamination during the first 24 h of the experiment. The tightening torques did not statistically affect the microleakage in the assemblies. However, the group that was tightened to 32 Ncm torque did not show any bacterial contamination. CONCLUSION: After 14 days of experimentation, the bacteria were proven to remain viable inside the implant internal cavity.

Micro-leakage at the implant-abutment interface with different tightening torques in vitro

OBJECTIVES: This study evaluated the microleakage at the implant/abutment interface of external hexagon (eH) implants and abutments with different amounts of bacteria and tightening torques. MATERIAL AND METHODS: A bacterial suspension was prepared to inoculate the implants. The first phase of this study used nine EH implants and abutments that were divided into three groups with different amounts of bacterial suspension (n=3): V0.5: 0.5 µL; V1.0: 1.0 µL e V1.5: 1.5 µL, and tightened to the manufacturer's recommended torque. The second phase of this experiment used 27 assemblies that were similar to those used in the first phase. These samples were inoculated with 0.5 µL of bacterial suspension and divided into three groups (n=9). T10: 10 Ncm; T20: 20 Ncm and T32: 32 Ncm. The samples were evaluated according to the turbidity of the broth every 24 hours for 14 days, and the bacteria viability was tested after that period. The statistical evaluation was conducted by Kruskal-Wallis testing (p<.05). RESULTS: During the first phase, groups V1.0 and V1.5 was presented with bacterial contamination in all samples after 24 h. During the second phase, two samples from group T10 and one from T20 presented positive results for bacterial contamination. Different amounts of bacterial solution led to overflow and contamination during the first 24 h of the experiment. The tightening torques did not statistically affect the microleakage in the assemblies. However, the group that was tightened to 32 Ncm torque did not show any bacterial contamination. CONCLUSION: After 14 days of experimentation, the bacteria were proven to remain viable inside the implant internal cavity.