Microwave disinfection of facial silicone prostheses, part 2: Mechanical properties.

STATEMENT OF PROBLEM: Part 1 of this 2-part study determined that microwave disinfection did not degrade the color stability of facial silicone prostheses. However, investigations on the effects of microwave disinfection on the mechanical properties of different silicone elastomers are lacking. PURPOSE: The purpose of this in vitro study was to examine the mechanical properties of commonly used colored facial silicone elastomers before and after microwave disinfection over a simulated 1.5-year period. MATERIAL AND METHODS: Six commonly used facial silicone elastomers: MDX4-4210, MDX4-4210/Type A, M511, A-2186, VST-50, and A-2000 were combined with functional intrinsic silicone pigments and opacifier (red, yellow, blue, and white). A total of 288 specimens were fabricated (n=12). Half of the specimens were tested for mechanical properties as the baseline, while the other specimens were tested after microwave disinfection. Microwave disinfection was performed with 660 W, 6 minutes of exposure time, and microwaved for 18 cycles to simulate 1.5 years of usage (one 6-minute exposure monthly). For mechanical property testing, all specimens were tested for tensile strength and percentage elongation (ASTM D412), tear strength (ASTM D624), and hardness (ASTM D2240). For each property, a 2-way ANOVA (silicone type and microwave disinfection factors) and Tukey multiple comparison test were performed using the R statistical software program (α=.05). RESULTS: Following microwave disinfection, tensile strength and percentage elongation of A-2000 increased significantly (P<.05). MDX4-4210, MDX4-4210/Type A, and A-2000 showed significant increases in their hardness (P<.001). Tear strength also increased significantly for MDX4-4210 and VST-50 (P<.05). Among the materials tested (ranked from highest to lowest value,=not statistically significant different), for tensile strength, VST-50>A-2186=A-2000>MDX4-4210/Type A=M511=MDX4-4210 (P<.05). For percentage elongation, VST-50>MDX4-4210/Type A>A-2186>M511=A-2000=MDX4-4210=M511 (P<.05). For hardness, A-2000=A-2186>M511=VST-50>MDX4-4210>MDX4-4210/Type A (P<.05). For tear strength, VST-50>A-2186>A-2000>M511>MDX4-4210/Type A=MDX4-4210 (P<.05). CONCLUSIONS: Overall, the mechanical properties of all the silicones tested were not adversely affected by microwave disinfection. VST-50 showed the best mechanical properties among the materials tested both before and after microwave disinfection. Microwave energy is a safe method of disinfecting the silicone elastomers tested in this study.

Training of novice surgeons using dynamic computer assisted dental implant surgery: An exploratory randomized trial.

BACKGROUND: Dynamic Computer Assisted Implant Surgery (CAIS) systems have been shown to improve accuracy of implant placement, thus training in the use of such systems is becoming increasingly important. There is a scarcity of research on how to implement dynamic CAIS training in the settings of postgraduate university education. PURPOSE: To determine the effectiveness of two modes of CAIS training programs on motor skill acquisition of novice surgeons. MATERIALS AND METHODS: Thirty-six postgraduate students without experience in dynamic CAIS systems were randomly assigned to a distributed training program (3 training sessions over 3 days) or a massed training (3 training sessions over the same day). A post-test involving the placement of one implant was conducted for both groups, 7 days after completion of the training. Surgical time and implant accuracy were recorded and analyzed, using independent t-tests, with 0.05 significant level. RESULTS: Both groups reached the accuracy benchmarks expected by current standards in the use of CAIS. No significant differences with regards to accuracy were found between the groups, but a trend was documented favoring performance of distributed (mean difference-0.4, 95% confidence interval-0.7-0.1) in the accuracy at platform level. Distributed training students performed faster than massed for the third trial (mean difference-95.0, 95% confidence interval-178.8 to -11.2). CONCLUSIONS: Novice students reached the accuracy benchmarks with the use of CAIS through both a massed and a distributed training program, while there was a strong but marginally not significant trend for higher accuracy in the distributed group. Students who received the training in the distributed format over the process of different days, performed faster. Trial registered in Thai Clinical Trials Registry: https://www.thaiclinicaltrials.org/show/TCTR20230109002. This clinical trial was not registered prior to participant recruitment and randomization.

Effect of Different Post Materials and Adaptability on Fracture Resistance and Fracture Mode in Human Endodontically Treated Teeth.

Objective: To investigate the effect of different post materials and adaptability on fracture resistance and fracture mode of endodontically treated teeth. Materials and Methods: Sixty extracted human mandibular premolars were selected and divided into 6 groups (n = 10) according to the restorative method after endodontic treatment: no ferrule presented and restored without fiber post (Group C), 2.0 mm ferrule presented and restored without fiber post (Group CF), restored with D.T. Light-Post (Group PDT), restored with anatomically customized D.T. Light-Post, relined with resin composite (Group ADT), restored with Hi-Rem prosthetic post (Group PHR), and restored with anatomically customized Hi-Rem prosthetic post, relined with resin composite (Group AHR). After restoring with core build-up materials, all specimens were loaded at 45° in a universal testing machine until failure. Visual inspection of all specimens for fracture modes was performed. The data were analyzed using one-way ANOVA, and the fracture mode was reviewed using the chi-square test. Results: Anatomically customized groups presented statistically significant higher fracture resistance than prefabricated groups and group C (P < 0.05). Without post, group CF displayed significantly higher fracture resistance than group C (P < 0.05). Group C, CF, PDT, and PHR showed some specimens with unfavorable fractures. Conclusions: Anatomically customized posts presented highest fracture resistance among all groups. There was no significant difference in fracture mode across all groups.

Associations among the anterior maxillary dental arch form, alveolar bone thickness, and the sagittal root position of the maxillary central incisors in relation to immediate implant placement: A cone-beam computed tomography analysis.

Purpose: This study evaluated the associations of the dental arch form, age-sex groups, and sagittal root position (SRP) with alveolar bone thickness of the maxillary central incisors using cone-beam computed tomography (CBCT) images. Materials and Methods: CBCT images of 280 patients were categorized based on the dental arch form and age-sex groups. From these patients, 560 sagittal CBCT images of the maxillary central incisors were examined to measure the labial and palatal bone thickness at the apex level and the palatal bone at the mid-root level, according to the SRP classification. The chi-square test, Kruskal-Wallis test, and multiple linear regression were used for statistical analyses. Results: Significant differences were found in alveolar bone thickness depending on the arch form and SRP at the apex level. The square dental arch form and class I SRP showed the highest bone thickness at both levels of the palatal aspect. The taper dental arch form and class II SRP presented the highest bone thickness at the apex level of the labial aspect. No association was found between the dental arch form and SRP. Elderly women showed a significant association with thinner alveolar bone. Age-sex group, the dental arch form, and SRP had significant associations with alveolar bone thickness at the apex level. Conclusion: The patient's age-sex group, dental arch form, and SRP were associated with alveolar bone thickness around the maxillary central incisors with varying magnitudes. Therefore, clinicians should take these factors into account when planning immediate implant placement.

The influence of implant design on implant stability in low-density bone under guided surgical template in inexperienced surgeons: A pilot randomized controlled clinical trial using resonance frequency analysis.

INTRODUCTION: There are several factors that greatly influence implant stability with implant design being a paramount factor; however, few studies investigate its impact. AIM: To investigate the implant stability in relation to two different implant designs, a cylindrical shaped single-threaded design (CS/ST) and a tapered shaped double-threaded design (TS/DT) using resonance frequency analysis over the first 8 weeks after implantation. MATERIALS AND METHODS: Twenty-eight implants were randomly allocated using computer-generated random numbers into two groups and were placed as single tooth implant in the posterior arch in human jaw as specimens. iCAT™ CBCT scan (Hatfield, PA) was used to determine the bone density according to Misch's Bone classification. The osseotomy sites were prepared and implants were placed with guided surgical template by inexperienced surgeons which were prepared with the same implant planning software (3shape® implant studio). The implant stability was measured using the resonance frequency analysis Osstell® ISQ (Osstell AB, Sweden) on the implant level over the first 8 weeks at three different time intervals. A mean implant stability quotient (ISQ) value was recorded at each measurement time points. The first ISQ of each implant recorded at the time of implant placement were considered as baseline and were the so-called primary stability. RESULTS: All 28 dental implants were analyzed. A similar pattern of implant stability changes was observed in both implant designs. A significant decreased was found at the first 4 weeks after implantation (p < 0.05) before ascending to maximum cumulative stability by the eighth week (p < 0.05). Between the two groups, TS/DT group had a higher mean ISQ values than that of the CS/ST group at all three observation periods but did not reach statistical significance (p = 0.69). Regarding different types of bone, TS/DT showed a significant difference in mean ISQ values in D4 bone. To date, all 28 implants are in function with no failure/and or complications. CONCLUSIONS: The difference in implant design did not significantly influence the implant stability. TS/DT shows superiority over CS/ST when placed in D4 bone and offer a significant advantage due to their positive bounce back of the ISQ values by the eighth week after implant installation. CLINICAL TRIAL REGISTRATION: TCTR20211020005.

A randomized clinical trial on the accuracy of guided implant surgery between two implant-planning programs used by inexperienced operators.

STATEMENT OF PROBLEM: Various static implant planning software packages have been developed for the purpose of static computer-assisted implant surgery. However, how different software programs affect the accuracy of implant placement is unclear. PURPOSE: The purpose of this clinical study was to evaluate and examine the difference in posterior implant positioning between the planned and placed positions when inexperienced operators, following a fully guided implant surgery protocol, used 2 static implant planning software packages. MATERIAL AND METHODS: Twenty-four participants who needed single posterior implant placement were randomly divided into 2 groups based on the used implant planning software program (coDiagnostiX, n=12; Implant Studio, n=12). The dataset of the placed implant position, generated by digitizing the implant impression, was superimposed on the planned implant position. The number of horizontal, angular, and vertical deviations of the placed implants were measured for each software package and statistically analyzed with the independent t test (α=.05). RESULTS: The coDiagnostiX group presented with a mean horizontal deviation at the entry point (DE) of 1.07 ±0.36 mm, mean angular deviation (DA) of 3.52 ±1.64 degrees, and mean depth deviation (DD) of -0.71 ±0.29 mm, while the mean DE, mean DA, and mean DD in the Implant Studio group were 0.97 ±0.33 mm, 3.77 ±2.16 degrees, and -0.84 ±0.30 mm, respectively. Statistically, no significant differences were found between coDiagnostiX and Implant Studio programs for all these results (P>.05). CONCLUSIONS: Acceptable accuracy of implant positioning can be expected by inexperienced operators if they follow the guidelines of either of the 2 software packages. Both the coDiagnostiX and Implant Studio programs showed similar results, with a shallower than planned implant depth of 0.71 and 0.84 mm, respectively.

Comparison of the shear bond strength of composite resins with zirconia and titanium using different resin cements.

PURPOSE: The shear bond strength of conventional zirconia (3Y-TZP), translucent zirconia (5Y-PSZ), and titanium alloy (Ti6Al4V) thermocycled using different phosphate monomer resin cements were investigated. METHODS: In this study, 120 specimens of 3Y-TZP, 5Y-PSZ, and Ti6Al4V were cemented to nanocomposite resin cylinders using PANAVIA™ V5 and Rely X™ U200. The bond area and resin cement thickness were controlled as per ISO 29022:2013 and 4049:2009. Each resin cement group was used with/without the Clearfil ceramic primer plus. The shear bond strength of the 12 groups was statistically analyzed using two and one-way ANOVA to determine the properties of the different materials and resin cements (α = 0.05). The mode of failure was observed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). RESULTS: The titanium alloy groups showed better shear bond strength than the zirconia groups (p < 0.05). PANAVIA™ V5 without primer showed significantly lower shear bond strength than other cements in zirconia and titanium alloy specimens (p < 0.05). Titanium alloy with Rely X™ U200 with a Clearfil ceramic primer plus showed the highest shear bond strength (6.37 ± 1.60 MPa). SEM images showed mixed failures in zirconia groups and cohesive failures in titanium alloy groups. CONCLUSION: The titanium alloy showed better shear bond strength than zirconia when the Clearfil ceramic primer plus was used. The primer solution containing MDP and resin cement with phosphoric methacrylate ester showed similar shear bond strength with 3Y-TZP and 5Y-PSZ. The resin cement without phosphate monomers demonstrated the least shear bond strength.

Immunohistochemical assessment of the peri-implant soft tissue around different abutment materials: A human study.

BACKGROUND: Soft tissue reaction to dental implant abutments influences the sustainability of restoration. Several abutment materials, such as titanium and gold alloy, have been introduced for strength and esthetic solutions. Zirconia and titanium-base abutments have also become popular in recent years due to high esthetic demands. PURPOSE: To investigate the immune cell infiltration into the soft tissue in response to different abutment materials. MATERIALS AND METHODS: Twenty dental implants were placed in the posterior regions of 17 patients. Titanium, zirconia, gold alloy, and titanium-base were randomly selected for each patient on the day of surgery. After 8 weeks of healing, the abutments were removed along with 1 mm of peri-implant soft tissue. Immunohistochemical assessment was performed using labeled streptavidin-biotin to identify T cells, B cells, macrophages, plasma cells, and microvascular infiltration. RESULTS: Gold alloy demonstrated an overall higher inflammatory cell infiltration and highest number of CD3+ , CD20+ , and CD 68+ cells (P value <.05). The number of plasma cell and new microvascular infiltrations among abutment materials was not significantly different. CONCLUSION: Titanium, titanium-base, and zirconia abutments showed comparable infiltration profiles; gold alloy abutments showed the highest B-cell, T cell, and macrophage infiltration. None of the abutment materials caused clinical inflammation; hence, they can be effectively used.

Influence of the anterior arch shape and root position on root angulation in the maxillary esthetic area.

PURPOSE: This study was conducted to characterize the relationship of the angulation between the tooth root axis and alveolar bone axis with anterior alveolar (AA) arch forms and sagittal root position (SRP) in the anterior esthetic region using cone-beam computed tomography (CBCT) images. MATERIALS AND METHODS: CBCT images that met the inclusion and exclusion criteria were categorized using a recent classification of AA arch forms and a SRP classification. Then, the angulation of the root axis and the alveolar bone axis was measured using mid-sagittal CBCT images of each tooth. The relationships of the angulation with each AA arch form and SRP classification were evaluated using 1-way analysis of variance and a linear regression model. RESULTS: Ninety-eight CBCT images were included in this study. SRP had a greater influence than the AA arch form on the angulation of the root axis and the alveolar bone axis (P<0.05). However, the combination of AA arch form and SRP was more predictive of the angulation of the root axis and the alveolar bone axis than either parameter individually. CONCLUSION: The angulation of the root axis and alveolar bone axis demonstrated a relationship with the AA arch form and SRP in teeth in the anterior esthetic region. The influence of SRP was greater, but the combination of both parameters was more predictive of root-to-bone angulation than either parameter individually, implying that clinicians should account for both the AA arch form and SRP when planning implant placement procedures in this region.

A Clinical Resonance Frequency Analysis of Implants Placed at Dehiscence-type Defects with Simultaneous Guided Bone Regeneration During Early Healing.

PURPOSE: To investigate the implant stability quotient (ISQ) values of implants placed in bone with and without dehiscence bone defects over 12 weeks and to compare the ISQ values between the two groups. MATERIALS AND METHODS: Twenty-two patients with edentulous area at posterior mandible were enrolled. Thirty OsseoSpeed EV Astra Tech implants (Dentsply Sirona), 4.2 mm in diameter, were placed. Twenty implants were placed without bone regeneration (control group), while 10 presented with favorable bone defects and received simultaneous guided bone regeneration with dental implant placement (study group). At the time of implant placement, 2, 4, 8, and 12 weeks, resonance frequency analysis (RFA) was utilized. The changes in ISQ values within group were analyzed with repeated-measures ANOVA, and the mean ISQ values between the control and study groups were compared using unpaired t tests. RESULTS: All implants were successfully integrated without complication. The control group demonstrated mean ISQ values of 74.30 ± 6.01, 69.58 ± 5.30, 71.10 ± 5.80, 75.08 ± 3.93, and 77.85 ± 3.18 at baseline, 2, 4, 8, and 12 weeks, respectively. The study group demonstrated mean ISQ values of 69.85 ± 7.00, 63.40 ± 8.47, 59.90 ± 10.23, 72.55 ± 3.10, and 76.20 ± 2.68 at baseline, 2, 4, 8, and 12 weeks, respectively. The study group showed significantly lower mean ISQ values at 2 weeks (P = .021) and at 4 weeks (P = .007) after implant placement compared to those of the control group. CONCLUSION: Within the 12-week healing period, all implants demonstrated successful osseointegration and achieved stability in favorable bone defects. Nevertheless, clinicians should consider that significantly lower implant stability can occur in the first month.

Histological evaluations and inflammatory responses of different dental implant abutment materials: A human histology pilot study.

BACKGROUND: Improvements of soft tissue to the abutment surface results in more stable peri-implant conditions, however, few human histological studies have compared soft tissue responses around different abutment materials. PURPOSE: To describe the peri-implant tissue around 3 abutment materials; titanium, zirconia, and gold alloy, over an 8-week healing period. MATERIALS AND METHODS: Fifteen edentulous sites were treated with implants. Eight weeks later, peri-implant tissue was harvested and processed using a nonseparation resin embedded technique. The tissue attachment characteristics were assessed at clinical stages using the gingival index (GI) score, surgical stage (surgical score), and histological stage (histological attachment percentage). Additionally, the inflammatory responses were evaluated using inflammatory extent and inflammatory cellularity grades. Nonparametrical statistics were used to describe the GI and surgical scores, and analytical statistics were used to analyze the histological attachment percentages as well as the inflammatory extent and cellularity grades amongst the 3 groups. RESULTS: There were no statistically significant differences among the groups for GI score (P = .071) and surgical score (P = .262). Titanium and zirconia exhibited nearly similar mean histological attachment percentages while gold alloy had a significantly lower percentage (P = .004). For the inflammatory extent and cellularity grades, the odds of being one grade higher for gold alloy abutment was 5.18 and 17.8 times that of titanium abutment, respectively. However, for the zirconia abutment, the odds were 0.87 and 7.5 times higher than the titanium group. CONCLUSIONS: The tissue around the gold alloy abutments resulted in worse attachment conditions compared with the titanium and zirconia abutments. Inflammation tended to be higher in the tissue around the gold alloy abutments than the titanium and zirconia abutments.

Bony spicules trapped in peri-implant soft tissue: a common unrecognized finding.

According to the study, there were unexpected tiny bone spicules being inspected in peri-implant soft tissue. These displaced autogenous bone chips were probably presented when preparing implant sites. The displaced bone spicules seemed not induced significant inflammatory reactions; on contrary, defects of specimens and dissolving bone spicules pictures were demonstrated.

Oral health-related quality of life and esthetic outcome in single anterior maxillary implants.

OBJECTIVES: The aim of this study is twofold: to assess the esthetic outcome of single dental implant restorations in the anterior maxillary area after up to 3 years of function, and to evaluate the relationship between the esthetic outcome and oral health-related quality of life. MATERIALS AND METHODS: Twenty patients who were treated with an anterior maxillary single implant restoration were recalled for esthetic outcome evaluation using pink and white esthetic scores (PES/WES). All patients completed a questionnaire regarding satisfaction of treatment outcome and quality of life related to the implant restorations. Patient satisfaction was assessed by visual analog scales (VAS) analysis, whereas oral impact on daily life performances (OIDP) was used to evaluate the quality of life of patients. RESULTS: The esthetic outcome assessed by PES/WES showed favorable results. The median PES/WES scores were 16.00 (maximum possible score = 20). The median PES scores and WES scores were 7.50 and 8.00, respectively. Patient satisfaction rated in VAS scale ranged from 8 to 10. OIDP assessment showed an impact on daily life performance in 45% of patients. The most common impacts were eating (n = 5) and cleaning teeth (n = 4). No significant difference in PES/WES scores was found between the patients who perceived and did not perceive oral impacts. CONCLUSIONS: There was some discrepancy between the dentist's evaluation and patient's perception but a strong positive satisfaction was reported from all patients which let suppose that the psychosocial factors that involve patient's perspective should be further investigated.

Periimplant bacteria associated with different transmucosal designs or smoking habits.

PURPOSE: This study is to compare periimplant microbiota associated with implant transmucosal designs or smoking habits. METHODS: Submucosal samples from healthy 52 implants were collected for analysis of bacteria associated with bone-level (n = 37) or tissue-level (n = 15) implants or smoking habits, using quantitative polymerase chain reaction. Profiles of periimplant bacteria of smokers (n = 5) were investigated using PhyloChip Array version G3 and compared with nonsmokers (n = 5). RESULTS: The number of bone-level implants positive for at least 1 pathogen was higher than that of tissue level; however, differences in each bacterium were insignificant. The prevalence and abundance of Treponema denticola in smokers were significantly higher than that in nonsmokers (P < 0.05). Smokers and nonsmokers exhibited similar periimplant microbiota based on the PhyloChip Array, but they could be distinguished by limiting observations to only 18 operational taxonomic units. Streptococcus macedonicus within Firmicutes and Prevotella within Bacteroidetes were more abundant in smokers compared with nonsmokers. CONCLUSION: Prevalence of putative pathogens with bone-level implants was higher than tissue-level implants in nonsmokers. Firmicutes and Bacteroidetes were significantly higher in smokers. Smoking therefore strongly influenced peri-implant bacterial composition of bone-level implant.