Occupational Noise Exposure in the Pediatric Dental Setting.

Purpose: To evaluate the noise levels recorded in a hospital-based pediatric dental clinic and evaluate the occupational exposure personnel have to potentially hazardous levels of noise. Methods: A SoundAdvisor™ Sound Level Meter Model 831C was used to gather 19 days of background sound data (equivalent continuous sound levels, measured as LAeq) in the open bay, quiet room, sedation suite, and operating room settings. A Spartan™ Wireless Noise Dosimeter Model 730 (Larson Davis) was utilized to capture data about personal noise exposure of pediatric dental residents over 81 clinic sessions. Personal noise exposure was compared to the Occupational Safety and Health Administration (OSHA) stand- ard. Results: Background A-weighted sound pressure level was significantly less for the open bay than in the operating room, quiet room, and oral sedation setting (P<0.05), while the operating room was significantly less than the oral sedation setting (P=0.038). Personal LAeq was significantly less for the open bay than the quiet room (P=0.007) and oral sedation settings (P=0.007). There was a significantly larger percentage of time above 80 dBA captured in the oral sedation suite compared to the open bay (P=0.010) or operating room (P=0.023). Conclusions: Daily occupational noise exposure did not exceed the thresholds set forth by OSHA. Sedation and quiet room treatment settings were noted to be the loudest pediatric dental clinical environments.

Effects of shade and thickness on the translucency parameter of anatomic-contour zirconia, transmitted light intensity, and degree of conversion of the resin cement.

STATEMENT OF PROBLEM: Anatomic-contour zirconia prostheses are usually cemented with resin cement. However, information regarding the effects of the zirconia shade and thicknesses on the translucency of the prosthesis, the intensity of the transmitted light beneath the prosthesis, and the subsequent degree of conversion in the resin cement is sparse. PURPOSE: The purpose of this in vitro study was to investigate the translucency parameter in 3 anatomic-contour zirconia specimens of 2 shades at 5 different thicknesses and to investigate the transmitted light intensity and degree of conversion of the resin cement beneath the ceramic specimens by using a traditional zirconia and a lithium disilicate glass-ceramic as controls. MATERIAL AND METHODS: Ceramic specimens from 1 anatomic-contour zirconia in a generic shade (CAP FZ) and 2 anatomic-contour zirconias in A2 shade (Zirlux and Luxisse) were used. Lithium disilicate in HT A2 shade (IPS e.max CAD) and traditional zirconia in a generic shade (CAP QZ) were used as controls. A total of 125 ceramic specimens (n=25) were fabricated to a final specimen dimension of 12×12 mm and in thicknesses of 1.0, 1.25, 1.5, 1.75, and 2.0 mm according to the manufacturers' recommendations. The CIELab color space for all specimens placed against a white and black background was measured with a spectrophotometer (CM-2600D), and the translucency parameters were calculated for the materials at various thicknesses. A light-polymerizing unit (DEMI LED) was used to polymerize the resin cement (Variolink II) placed beneath the ceramic specimens. Transmitted light intensity from the polymerization unit beneath the ceramic specimens was measured by using a spectrophotometer (MARC Resin Calibrator), and the transmittance of each specimen was calculated. The coefficient of absorption of each material was calculated from the regression analysis between the natural log of transmittance and specimen thickness. The degree of conversion of resin cement was measured by using a Fourier transformation infrared (FTIR) spectrophotometer. The results were analyzed by using 2-way ANOVA (α=.05). The relationship between the transmittance and the translucency parameter was evaluated by plotting the transmittance against the translucency parameter value of each specimen. RESULTS: The translucency parameter decreased with increasing thickness in all 5 material groups. All anatomic-contour zirconia had lower translucency parameters than e.max CAD (P<.001). The same results were found for the intensity of the transmitted light (P<.001). Both A2 shade anatomic-contour zirconia (Zirlux and Luxisse) showed significantly lower light transmittance than a generic shade anatomic-contour zirconia (CAP FZ) (P<.001). The coefficients of absorption were found to range from 0.63 to 1.72 mm-1, and reflectance from 0.10 to 0.25. The results from the degree of conversion of resin cement after polymerization through 1 to 2 mm of specimens showed a significantly higher degree of conversion in the e.max group than in all other groups (P<.001). The correlation between translucency parameter and the intensity of the transmitted light suggested that the relationship was shade dependent. CONCLUSIONS: The translucency parameter and the transmitted light intensity of ceramic material were influenced by the type of ceramic and the shade and thickness of the ceramic. The combined effects of layer thickness and the intensity of the transmitted light in the A2 shade anatomic-contour zirconia (Zirlux and Luxisse) resulted in a lower degree of conversion in resin cement than in a generic shade anatomic-contour zirconia (CAP FZ) at layer thicknesses of 1.75 and 2 mm.

Fracture Resistance Behaviors of Titanium-Zirconium and Zirconia Implants.

PURPOSE: To evaluate the fracture resistance behaviors of titanium-zirconium, one-piece zirconia, and two-piece zirconia implants restored by zirconia crowns and different combinations of abutment materials (zirconia and titanium) and retention modes (cement-retained and screw-retained zirconia crowns). MATERIAL AND METHODS: Three research groups (n=12) were evaluated according to combinations of abutment material, retention mode, and implant type. In the control group (TTC), titanium-zirconium implants (∅ 4.1 mm RN, 12 mm, Roxolid; Straumann USA, Andover, MA) and prefabricated titanium abutments (RN synOcta Cementable Abutment, H 5.5 mm; Straumann USA) were used to support cement-retained zirconia crowns. In the second group (ZZC), one-piece zirconia implants (PURE Ceramic Implant Monotype, ∅ 4.1 mm RD, 12 mm, AH 5.5 mm; Straumann USA) were used to support cement-retained zirconia crowns. In the third group (ZTS), two-piece zirconia implants (PURE Ceramic Implant, ∅ 4.1 mm RD, 12 mm) and prefabricated titanium abutments (CI RD PUREbase Abutment, H 5.5 mm) were used to support screw-retained zirconia crowns. All zirconia crowns were manufactured in the same anatomic contour with a 5-axis dental mill and blended 3 and 5 mol% yttria-stabilized zirconia (LayZir A2). Implants were inserted into specimen holders made of epoxy resin-glass fiber composite. All specimens were then subject to artificial aging in an incubator at 37°C for 90 days. Fracture resistance of specimen assemblies was tested under static compression load using the universal testing machine based on ISO14801 specification. The peak fracture loads were recorded. All specimens were examined at the end of the test microscopically at 5× and 10× magnification to detect any catastrophic failures. Comparisons between groups for differences in peak fracture load were made using Wilcoxon Rank Sum tests and Weibull and Kaplan-Meier survival analyses (α = 0.05). RESULTS: The TTC group (942 ± 241 N) showed significantly higher peak fracture loads than the ZZC (645 ± 165 N) and ZTS (650 ± 124 N) groups (p < 0.001), while there was no significant difference between ZZC and ZTS groups (p = 0.940). The survival probability based on the Weibull and Kaplan-Meier models demonstrated different failure molds between titanium-zirconium and zirconia implants, in which the TTC group remained in the plastic strain zone for a longer period before fracture when compared to ZZC and ZTS groups. Catastrophic failures, with implant fractures at the embedding level or slightly below, were only observed in the ZZC and ZTS groups. CONCLUSIONS: Cement-retained zirconia crowns supported by titanium-zirconium implants and prefabricated titanium abutments showed superior peak fracture loads and better survival probability behavior. One-piece zirconia implants with cement-retained zirconia crowns and two-piece zirconia implants with screw-retained zirconia crowns on prefabricated titanium abutment showed similar peak fracture loads and survival probability behavior. Titanium-zirconium and zirconia implants could withstand average intraoral mastication loads in the incisor region. This study was conducted under static load, room temperature (21.7°C), and dry condition, and full impacts of intraoral hydrothermal aging and dynamic loading conditions on the zirconia implants should be considered and studied further.

Bonding between implant attachment pickup materials and CAD-CAM denture base material.

STATEMENT OF PROBLEM: Adequate bonding between pickup material and the newer generation of prepolymerized polymethyl methacrylate (PMMA) for computer-aided-design and computer-aided manufacturing (CAD-CAM) dentures is essential to the success of treatment. However, studies on the bond between these 2 materials are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the bond strength of 3 different chairside implant LOCATOR attachment pickup material groups and prepolymerized PMMA by investigating their pushout force. MATERIAL AND METHODS: Prepolymerized PMMA, (Lucitone 199) was used as the denture base material. The material was cut into 25×25×5-mm disks, and a Ø6.5-mm hole was drilled into the center of the disks. Six pickup materials from 3 groups were tested: composite resin with bonding agent (N=3, EZ PickUp, Quick Up, and Triad gel), composite resin without bonding agent (N=1, Chairside), and acrylic resin (N=2, Jet denture repair acrylic, and Duralay). All materials were prepared as per the manufacturers' recommendations and were used to fill the center hole. The specimens were left for 48 hours to completely polymerize before testing. Half of the specimens from each material then received thermocycling treatment. All specimens were subjected to axial pushout testing with a universal testing machine. RESULTS: In the nonthermocycled specimens, Duralay and Jet denture repair acrylic resin showed significantly higher pushout force than that of the other groups (P<.001). Triad gel showed higher pushout force than EZ PickUp and Quick Up (P<.001). Chairside showed the lowest push-out force. The same trend was also observed in the thermocycled specimens. The peak pushout force of nonthermocycled Chairside composite resin was significantly lower than that of thermocycled Chairside composite resin (P=.03). Conversely, the peak pushout force of nonthermocycled EZ PickUp specimens was significantly higher than that of thermocycled EZ PickUp specimens (P=.01). Variation in fracture patterns among groups was observed, and the correlation between pushout force and fracture patterns was recorded. CONCLUSIONS: Two materials from the acrylic resin group, Jet denture repair acrylic and Duralay, showed higher pushout forces, indicating a better bond with Lucitone 199 CAD-CAM denture base material compared with other tested materials, including composite resin with bonding agent (EZ PickUp, Quick Up, and Triad gel) and composite resin without bonding agent (Chairside).

Leadership diversity in prosthodontics: Number of women and nonwhite individuals serving as President of selected prosthodontic organizations in the last 20 years.

STATEMENT OF PROBLEM: As a measure of the leadership diversity in prosthodontics, the number and percentage of women and nonwhite Presidents of prosthodontics organizations is unknown. PURPOSE: The purpose of this observational study was to calculate and compare the number and percentage of women and nonwhite Presidents of 10 selected prosthodontic organizations over the past 20 years and to determine whether the number of women and nonwhite Presidents has changed over the time frame of 2000-2019 in comparison to male and white Presidents. MATERIAL AND METHODS: The number of women and nonwhite Presidents of the Academy of Prosthodontics (AP), American Academy of Fixed Prosthodontics (AAFP), American Academy of Maxillofacial Prosthetics (AAMP), American College of Prosthodontists (ACP), American Prosthodontic Society (APS), European Prosthodontic Association (EPA), International Association of Dental Research - Prosthodontics group (IADR-P), International College of Prosthodontists (ICP), Greater New York Academy of Prosthodontics (GNYAP), and Pacific Coast Society for Prosthodontics (PCSP) was recorded. The chi-square test was used to determine differences in the percentage of women and nonwhite Presidents over time and between organizations. RESULTS: The range of women Presidents in the selected years was 20% (EPA) to 0% (APS) with a mean of 10%. No statistically significant differences over time and between organizations were observed. The range of nonwhite Presidents in the selected years was 25% (ICP) to 0% (AAFP, AAMP, ACP, and GNYAP) with a mean of 7.5%. No statistically significant difference over time was observed while a statistically significant difference between organizations was observed (P=.015). Multiple comparisons revealed the ICP had significantly more nonwhite Presidents in the selected years. CONCLUSIONS: The relatively low numbers of women and nonwhite Presidents in the organizations studied is compelling evidence that there are an insufficient number of women and nonwhite role models in prosthodontics and that important voices representing the diversity of members of the prosthodontic community remain unheard.

Influences of build angle on the accuracy, printing time, and material consumption of additively manufactured surgical templates.

STATEMENT OF PROBLEM: Although desktop stereolithography (SLA) 3D printers and photopolymerizing resin have been used increasingly in dentistry to manufacture surgical templates, studies investigating their clinical application are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effects of build angle on the accuracy, printing time, and material consumption of additively manufactured surgical templates made with a desktop SLA 3D printer and photopolymerizing resin material. MATERIAL AND METHODS: Fifty surgical templates were fabricated from 1 master digital design file using a desktop SLA 3D printer and photopolymerizing resin material at 5 different build angles (0, 30, 45, 60, and 90 degrees) (n=10). All surgical templates were digitized and superimposed with the master design file using best-fit alignment in the surface matching software program. Dimensional differences between the sample files and the original master design files were compared, and the mean deviations were measured in the root mean square (measured in mm, representing accuracy). The printing time and resin consumption for each specimen were recorded based on the information in the 3D printing preparation software program. ANOVA and the Fisher least significant difference (LSD) test were used to estimate the effects of build angles on the root mean square, printing time, and resin consumption (α=.05 for all tests). RESULTS: The groups 0 degree (0.048 ±0.007 mm) and 45 degrees (0.053 ±0.012 mm) had statistically significant lower root mean square values when compared with those of groups 30 degrees (0.067 ±0.009 mm), 60 degrees (0.079 ±0.016 mm), and 90 degrees (0.097 ±0.017 mm) (P<.001 for all comparisons, except P=.003 for groups 30 degrees versus 45 degrees). The group 90 degrees had statistically significant higher root mean square values than all other groups (P<.001 for all comparisons, except P=.010 when compared with the group 60 degrees). For the printing time, the group 0 degree required significantly less printing time than all other groups (hour:minute, 1:26 ±0:03, P<.001 for all comparisons). The group 90 degrees required significantly more printing time than all other groups (2:52 ±0:06, P<.001 for all comparisons). For resin consumption, the groups 0 degree (11.58 ±0.21 mL), 30 degrees (11.32 ±0.16 mL), and 45 degrees (11.23 ±0.16 mL) consumed similar amounts of resin. However, there was statistical significance between groups 0 degree and 45 degrees (P=.016). The group 90 degrees consumed the significantly least amount of resin (9.86 ±0.40 mL, P<.001 for all comparisons). CONCLUSIONS: With a desktop SLA 3D printer, the 0-degree and 45-degree build angles produced the most accurate surgical template, and the 90-degree build angle produced the least accurate surgical template. The 0-degree build angle required the shortest printing time but consumed the most resin in the printing process. The 90-degree build angle required the longest printing time but consumed the least amount of resin in the printing process.

Leadership diversity in prosthodontics: Recommendations for the representation of women speakers at scientific prosthodontic meetings.

STATEMENT OF PROBLEM: Leadership platforms in the professions include invitations to speak at the meetings of major organizations. However, the percentage of women speakers at prosthodontic meetings is lower than that of women prosthodontists overall. Recommendations or reporting requirements to address this deficiency are lacking. PURPOSE: The purpose of this observational study was to determine the probability of the number of women speakers at any scientific meetings of 6 different prosthodontic organizations over the past decade occurring by chance alone and to make recommendations for scientific program committees and organizations regarding the number of women speakers at future meetings. MATERIAL AND METHODS: The number of men and women speakers at the 2009-2018 annual meetings of the Academy of Prosthodontics (AP), American Academy of Fixed Prosthodontics (AAFP), American College of Prosthodontics (ACP), American Prosthodontic Society (APS), Greater New York Academy of Prosthodontics (GNYAP), and Pacific Coast Society for Prosthodontics (PCSP) was recorded. The chi-square test was used to determine differences in the percentage of women speakers over time and between organizations. The BINOM.DIST function was used to calculate the probability of selecting the exact number of women speakers at each meeting (α=.05). RESULTS: The mean percentage of women speakers across all organizations and all years was 10.80%. The percentage ranged from 0.00% (AAFP 2013; ACP 2013; APS 2012, 2015; GNYAP 2009, 2014; and PCSP 2009, 2010, 2011) to 42.86% (AP 2013). No change in women speaker presence was observed over the time frame investigated. The AP had significantly more women speakers than the other organizations. Of the 60 meetings included, 25 meetings had a statistically significantly low number of women speakers, and 1 meeting had a statistically significantly high number of women speakers. CONCLUSIONS: The number of women speakers at the scientific meetings of the organizations analyzed was significantly low and has not changed significantly over the years from 2009 to 2018. There were significantly more women speakers at the scientific meetings of the Academy of Prosthodontics than in the 5 other major prosthodontic organizations over the years 2009 to 2018. A recommendation is made that prosthodontic organizations include more women speakers on scientific programs. Specifically, a minimum of 25% of speakers should be women (rolling 3-year average) or 25% of podium time should be for women speakers (rolling 3-year average).

Consideration for Contemporary Implant Surgery.

The advancement of technology often provides clinicians and patients better clinical alternatives to achieve optimal treatment outcomes. Computer-guided options allow clinicians to realize the virtual prosthodontically driven surgical plan, facilitating more predictable implant placement. Although the use of technology does not mean the clinicians can forgo the fundamental treatment principles when treating a patient, proper assessment and diagnostic approach from prosthodontic, surgical, and radiographic perspectives are still essential for a successful clinical outcome. The purpose of this article is to review the fundamental concepts for the use of computer-guided surgery to facilitate prosthodontic treatment.

Fatigue Failure Load of Lithium Disilicate Restorations Cemented on a Chairside Titanium-Base.

PURPOSE: To evaluate the fatigue failure load of distinct lithium disilicate restoration designs cemented on a chairside titanium base for maxillary anterior implant-supported restorations. MATERIALS AND METHODS: A left-maxillary incisor restoration was virtually designed and sorted into 3 groups: (n = 10/group; CTD: lithium disilicate crowns cemented on custom-milled titanium abutments; VMLD: monolithic full-contour lithium disilicate crowns cemented on a chairside titanium-base; VCLD: lithium disilicate crowns bonded to lithium disilicate customized anatomic structures and then cemented onto a chairside titanium base). The chairside titanium base was air-abraded with aluminum oxide particles. Subsequently, the titanium base was steam-cleaned and air-dried. Then a thin coat of a silane agent was applied. The intaglio surface of the ceramic components was treated with 5% hydrofluoric acid (HF) etching gel, followed by silanization, and bonded with a resin cement. The specimens were fatigued at 20 Hz, starting with a 100 N load (5000× load pulses), followed by stepwise loading from 400 N up to 1400 N (200 N increments) at a maximum of 30,000 cycles each. The failure loads, number of cycles, and fracture analysis were recorded. The data were statistically analyzed using one-way ANOVA, followed by pairwise comparisons (p < 0.05). Kaplan-Meier survival plots and Weibull survival analyses were reported. RESULTS: For catastrophic fatigue failure load and the total number of cycles for failure, VMLD (1260 N, 175,231 cycles) was significantly higher than VCLD (1080 N, 139,965 cycles) and CDT (1000 N, 133,185 cycles). VMLD had a higher Weibull modulus demonstrating greater structural reliability. CONCLUSION: VMLD had the best fatigue failure resistance when compared with the other two groups.

Maxillofacial Prosthetics.

The treatment of head and neck cancers requires a team approach. Maxillofacial prosthetics and oncologic dentistry are involved in many phases of the treatment. After the cancer ablation surgery, if surgical reconstruction cannot not completely restore the surgical defect site, maxillofacial prostheses plays an important role to rehabilitate the patient's mastication, swallowing, and speech. For patients undergoing chemoradiation therapy, the outcome is enhanced by jaw positioning stent and fluoride carrier mouthpiece. This perioperative care by maxillofacial prosthetics improves the posttreatment outcomes and the patient's quality of life.

Integrating a facial scan, virtual smile design, and 3D virtual patient for treatment with CAD-CAM ceramic veneers: A clinical report.

This clinical report describes a digital workflow using the virtual smile design approach augmented with a static 3-dimensional (3D) virtual patient with photorealistic appearance to restore maxillary central incisors by using computer-aided design and computer-aided manufacturing (CAD-CAM) monolithic lithium disilicate ceramic veneers.