The effect of digital diagnostic setups on orthodontic treatment planning.

INTRODUCTION: This study aimed to evaluate whether viewing digital treatment simulations influenced orthodontic treatment planning decisions or practitioners' confidence in their selected plans. METHODS: Records of 6 patients representing different case types (eg, missing teeth, crowding, sagittal discrepancies) were collected. A total of 22 orthodontists and 7 orthodontic residents viewed these records and formulated treatment plans for each case, indicating their most recommended plan and up to 2 alternative plans. After treatment planning each case, digital setups of each treatment plan indicated by the practitioner were shown. The practitioners were then asked if they still recommended their original plan, or if they would now recommend a different plan. Their confidence levels in the success of their plans were recorded before and after viewing the setups. RESULTS: After viewing the digital setups, there was a significant change in the treatment plan for 9.2% of the cases. These included modifications like changing the extraction pattern or proposing space closure rather than opening space for an implant. In an additional 14.4% of the cases, treatment plans underwent partial changes, like adding interproximal reduction or temporary anchorage devices. Practitioner confidence levels increased after viewing the setups. In cases where the treatment plan changed, the practitioner's confidence level in the plan increased the most, and the final confidence level was uniformly high among all practitioners. Practitioners reported the most helpful features of digital setups were the ability to superimpose the setup with the original model, determine the amount of tooth movement needed, check the final incisal relationship (overjet and overbite), and establish the amount of interproximal reduction required. CONCLUSIONS: Viewing digital setups resulted in changes to the treatment plans in about 24% of the cases. The use of digital setups was associated with higher levels of confidence in the selected plans.

Fluoride-Releasing Effect of a Modified Resin Denture Containing S-PRG Fillers on Salivary Fluoride Retention: A Randomized Clinical Study.

This study aimed to evaluate the clinical effect of a resin denture base containing 20wt% surface prereacted glass ionomer (S-PRG) fillers on saliva fluoride concentrations as a surrogate evaluation of caries control. The study was a double-blind randomized clinical trial with a total of 110 participants aged 35-60 years who wore a removable partial resin denture for 1.5 years. Subjects were randomly assigned to receive a partial resin denture fabricated either with or without 20wt% S-PRG fillers (n = 55 per group). After 14 days of wearing the dentures, 5,000 ppm fluoride gel was applied nightly on both sides of the denture before storing it in a denture box overnight every night for 1.5 years. The salivary fluoride concentration was measured at baseline, on days 1, 14, and 15, and at 3 months and 1.5 years of wearing the denture. A significant increase in salivary fluoride concentration in the S-PRG denture group was observed from baseline to day 1, followed by a significant decrease to an approximate baseline level. After recharge with 5,000 ppm fluoride gel, salivary fluoride increased markedly on day 15 and remained elevated at month 3 through to 1.5 years. The resin denture base containing 20wt% S-PRG fillers demonstrated an initial fluoride release that increased saliva fluoride concentrations, but the fluoride release from within the material was short lived. The long-term effect of sustained fluoride release from the denture when combined with a regular fluoride recharge regimen may be beneficial for caries prevention.

Effects of carbodiimide dentin surface treatment on resin-dentin bonding.

PURPOSE: To assess the effects of ethanol-based 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide (EDC) dentin surface treatment on resin-dentin bonding and dentin collagen fibril biodegradation. METHODS: Acid-etched dentin surfaces were pretreated with different concentrations of ethanol-based EDC solutions (0.01-2M) for 60 seconds, followed by two-step etch-and-rinse dentin adhesive application and resin composite bonding. Dentin surfaces pretreated with either ethanol alone or no pretreatment were used as controls. The specimens were subjected to microtensile bond strength testing after storage in 0.9% NaCl solution at 37°C for either 24 hours or 90 days. Furthermore, demineralized dentin slabs with and without ethanol-based EDC pretreatment were exposed to a collagenase solution for 24 hours, and subsequent hydroxyproline release was measured using ELISA. Data were analyzed with ANOVA and multiple comparison tests at α= 0.05. RESULTS: The bond strength values were significantly lower for dentin surfaces pretreated with 1 and 2 M ethanol-based EDC than for the control surfaces (P< 0.05). The 0.01, 0.1, and 0.3 M ethanol-based EDC pretreated groups obtained significantly higher bond strength values at 90 days compared to controls. Hydroxyproline release measurements revealed that there were significantly lower levels released in the 0.3 and 1 M ethanol-based EDC pretreated specimens than for controls (P< 0.05). CLINICAL SIGNIFICANCE: Pretreatment of dentin surfaces with ethanol-based EDC solution ≤ 0.3M before resin composite bonding can improve the stability of the resin-dentin bond and prevent dentin collagen fibril biodegradation.

Critical appraisal: approaches to caries removal: what the clinical evidence says.

Every day in the United States, complete caries removal in vital, asymptomatic teeth with deep carious lesions ends in unavoidable exposure of the pulp. As a result, the complexity and cost of treatment increases dramatically and many patients are left with extraction as their only viable option. This review appraises evidence which supports alternative treatments designed to preserve the vitality of the tooth and thus avoid extraction.

Effect of silver diammine fluoride and glass ionomer on remineralisation of natural dentine caries.

OBJECTIVES: Silver diammine fluoride (SDF) is a caries-arresting agent for dentine lesions. This study investigated the effect of application frequency of SDF when used with glass ionomer cement (GI) for remineralising carious dentine. METHODS: Freshly extracted human posterior teeth with advanced caries were used. After superficial removal of infected dentine, single (G3), double (G4), triple (G5) applications of SDF (Advantage Arrest SDF 38 %) followed by a layer of GI (GC Fuji IX GP) were compared to no treatment (negative control-G2), and GI only (G1). All teeth were stored in artificial saliva between treatments and for 2-weeks after final treatment. Micro-computed X-ray tomography (NSI) scans were obtained at each stage and analysed to plot mineral density-depth profile, lesion depth (LD) and mineral loss (ΔZ). Data was statistically analysed at a significance level of 0.05. RESULTS: Mean LD values were 837 µm, 735 µm, 841 µm, 1008 µm, 707 µm at baseline and 785 µm, 727 µm, 712 µm, 855 µm, 639 µm after treatment for groups G1 to G5, respectively. Mean ΔZ values were 6327 vol%µm, 5995 vol%µm, 10014 vol%µm, 7192 vol%µm, 5649 vol%µm at baseline and 3686 vol%µm, 5126 vol%µm, 5539 vol%µm, 2327 vol%µm, 3218 vol%µm after treatment for groups G1 to G5, respectively. Paired t-test showed that LD and ΔZ changed significantly within all groups from baseline to treatment weeks following storage (p < 0.05) except LD in the control (p > 0.05). ANCOVA showed significant difference among groups in net lesion depth recovery and net mineral gain (p < 0.05), and G3 and G4 showed the highest mineral gains. CONCLUSION: One or two applications of SDF prior to placement of GI, were effective in remineralising advanced dentine lesions, while additional applications, when combined with GI, did not demonstrate additional benefit in this study. CLINICAL SIGNIFICANCE: This short-term laboratory research study showed that one or two applications of SDF followed by GI coverage could remineralise advanced dentine caries in the presence of artificial saliva. This procedure carries potential in the treatment of difficult lesions where conventional restorations would require significant tooth structure removal through traumatic procedures.

Use of a Knowledge-Based Governance Approach to Plan a Post-COVID-19 Predoctoral Dental.

COVID-19 abruptly changed dental education, forcing educators out of their comfort zones and into using new technologies and teaching approaches. At the University of Washington School of Dentistry, a task force evaluated the curricular changes that resulted from COVID and made recommendations for the future predoctoral dental curriculum. This manuscript reports the process employed, the findings of the task force, and how these findings will impact the curriculum. A knowledge-based governance (KBG) approach was employed. KBG focuses on gathering all relevant information and identifying all choices. It separates dialogue from deliberation. Information was gathered via literature review, focus group interviews, electronic surveys, and other metrics. The task force evaluated: (1) delivering didactic content remotely; (2) administering assessments remotely; (3) duplicating preclinical simulation lab courses due to social distancing; and (4) the conversion from a numerical to a credit/no credit grading scale. Key recommendations resulted from focus groups and electronic surveys that allowed any student or faculty member an opportunity to provide input. Some topics were relatively non-controversial and strong recommendations were evident. The most controversial issue was which grading scale should be utilized. A KBG approach is an effective means to address mega issues in the dental school environment.

In Vitro Study on the Effect of a New Bioactive Desensitizer on Dentin Tubule Sealing and Bonding.

Bioactive mineral-based dentin desensitizers that can quickly and effectively seal dentinal tubules and promote dentin mineralization are desired. This in vitro study evaluated a novel nanohydroxyapatite-based desensitizer, Predicta (PBD, Parkell), and its effect on bond strength of dental adhesives. Human dentin discs (2-mm thick) were subjected to 0.5 M EDTA to remove the smear layer and expose tubules, treated with PBD, and processed for surface and cross-sectional SEM examination before and after immersion in simulated body fluid (SBF) for four weeks (ISO 23317-2014). The effects of two dental desensitizers on the microshear bond strength of a universal adhesive and a two-step self-etch system were compared. SEM showed coverage and penetration of nanoparticles in wide tubules on the PBD-treated dentin at the baseline. After four weeks in SBF, untreated dentin showed amorphous mineral deposits while PBD-treated dentin disclosed a highly mineralized structure integrated with dentin. Desensitizers significantly reduced microshear bond strength test (MSBS) of adhesives by 15-20% on average, depending on the bonding protocol. In conclusion, PBD demonstrated effective immediate tubules sealing capability and promoted mineral crystal growth over dentin and into the tubules during SBF-storage. For bonding to desensitizer-treated dentin, a two-step self-etching adhesive or universal bond with phosphoric acid pretreatment are recommended.

Management of idiopathic subgingival amalgam hypertrophy--the common amalgam overhang.

An amalgam overhang is defined as an extension of amalgam restorative material beyond the confines of a cavity preparation. The pseudo pathology term "idiopathic subgingival amalgam hypertrophy" is used in the title for shock effect and as a scare tactic to catch the attention of our readers. From various studies, it is apparent that such overhangs are alarmingly common. The overhang is largely iatrogenic, caused by poor operator skill exacerbated by unusual dental morphology. Creep may also play a role in the gingival overhang of large amalgam restorations. Maybe we, as clinicians, are becoming complacent and lax in our techniques and matrixing while restoring such a routine restoration. This article revisits the pros and cons of different methods of amalgam overhang management with clinical cases for illustration.

Dental School Patient Preferences for Receiving and Returning Patient Satisfaction Surveys.

The aims of this study were to investigate dental school patient, parent, and caregiver preferences for receiving and returning patient satisfaction surveys and to determine how modes of receiving and returning surveys impacted return rates. Two studies were conducted, both of which are reported. In Study 1, adult patients, parents of child patients, and caregivers of patients with special needs were asked to indicate their preferred mode of receiving and returning surveys. In Study 2, patients, parents, and caregivers were randomly assigned to different modes of receiving and returning surveys, and return rates were compared between modes and according to whether the individuals had been assigned to their preferred mode or not. The overall response rates were 90.4% for the first study and 48.1% for the second study. In both studies, the preferred mode was receiving and returning the survey in the clinic (chi-square=84.902 and 32.116; df=3; p<0.001). Younger respondents were more likely to prefer receiving and returning the survey by email (K-W statistics=13.406, 10.241; df=3; p=0.004 and 0.017). In Study 2, respondents were significantly more likely to return surveys in the clinic (chi-square=44.994; df=2; p<0.001) and were also significantly more likely to return surveys if they had received them in their preferred mode (binomial test p<0.001). Although receiving and returning the survey in the clinic was the preferred mode, these respondents' preferences were also related to their age. These results suggest that dental school clinics may be able to expect higher return rates if they can follow patients' preferences for receipt and delivery of surveys.

Clinical evaluation of the soft-start (pulse-delay) polymerization technique in Class I and II composite restorations.

UNLABELLED: The polymerization shrinkage of resin composites may affect restoration quality. A double blind, randomized clinical trial was carried out to compare two curing techniques-Soft-Start (SS) and the plasma arc curing light (PAC). The hypothesis that, delaying the gel point (with SS) improves marginal seal, was tested at alpha = 0.05. Also, this report includes two-week, three-month, one-year and two-year results for post-op sensitivity. Twenty informed participants, each needing two Class II and/or complex Class I restorations, gave written consent. All the teeth were trans-illuminated to rule out pre-op crack lines before restoration placement. Fifty Z100-Single Bond restorations (25/SS and 25/PAC) were placed under rubber dam. Protocols: PAC (Control)-incremental curing < 2.0 mm, 2000 mW/cm2 for 10 seconds for all layers, SS (Treatment)-incremental curing <2.0 mm, 600 mW/cm2 for 20 seconds, except the final layer or enamel replacement increment, which was cured as follows-(mW/cm2/time) 200/3 seconds, wait 3 minutes; 200/3 seconds, wait 5 minutes; 600/20 seconds from multiple angles. Sensitivity to a standardized cold stimulus was performed preoperatively at 2 weeks and at 3, 12 and 24 months. Patients rated their sensitivity after stimulus by means of a Visual Analog Scale (VAS). In addition, two independent, calibrated investigators evaluated the restorations clinically at each appointment. There were no significant differences in VAS scores between the two groups at any appointment period (two-way ANOVA; p > 0.05). Several conditions were defined as indicating marginal stress before the start of the trial. At 24 months, there was no significant difference between the SS and PAC groups. CONCLUSION: Within the limitations of this study, Class I and II restorations placed with a SS technique did not show significant changes in post-op sensitivity or decreased signs of marginal stress.

Bleachorexia-an addictive behavior to tooth bleaching: a case report.

Bleachorexia, addiction to tooth bleaching, is a behavioral disorder similar to anorexia. The patient feels that their teeth are always not white enough and continues to use whiteners to obtain a "perfect" smile. Such behavior falls under the category of a body dysmorphic disorder and may need medical counseling.

Tensile bond strength of dual curing resin-based cements to commercially pure titanium.

OBJECTIVES: The aim of this study was to evaluate the tensile bond strength of dual curing luting resin cements to commercially pure titanium at 10 min and 24h after removal of the oxide layer. METHODS: One hundred and twenty titanium discs were obtained by casting and polishing with silicon carbide papers. The titanium discs were sandblasted with 50 microm aluminum oxide, ultrasonic cleaned and bonded in pairs with the resin-based cements Panavia F and Rely X ARC at 10 min and 24h after the sandblasting. The tensile test was performed with a crosshead speed of 0.5mm/min in an Instron Universal testing machine. RESULTS: The Rely X ARC reached the highest tensile strength value at 24h after sandblasting (18.27 MPa), but there was no statistically significant difference between the two dual curing resin cements for both times tested. All specimens showed a mixture of cohesive fracture in the resin cement and adhesive failure. However, the predominant failure mode for Panavia F was cohesive in resin cement, and the Rely X ARC exhibited a greater proportion of specimens with adhesive failure between the alloy and resin luting cement at 10 min and 24h. SIGNIFICANCE: Both cements had, statistically, the same tensile bond strength. But in the fracture mode analysis, the adhesive predominant fracture mode of Rely X ARC cement indicates a premature clinical adhesive failure. On the other hand, the cohesive predominant fracture mode of Panavia F indicates a longer clinical adhesive bond with titanium.

Effect of solvent type and content on monomer conversion of a model resin system as a thin film.

OBJECTIVE: The purpose of this study was to examine the effect of solvent concentration on the degree of conversion of a model photo-activated resin formulation when placed as a thin film in ambient air. METHODS: A photo-activated co-monomer mixture (ethoxylated bis-GMA/TEGDMA) (Bisco Inc.) was diluted into six concentrations (from 1.0 to 13.0M) with either acetone or ethanol. A controlled volume of diluted, uncured resin was placed on the horizontal surface of an attenuated reflectance unit and the infrared (IR) spectrum obtained. A light emitting diode light-curing source (Bluephase, Ivoclar/Vivadent) then immediately irradiated the specimen for 10s (n=5). Five minutes after exposure, IR spectra of the cured material were obtained, and monomer conversions were calculated using standard methods that monitored changes in aliphatic-to-aromatic CC absorbance ratios in the uncured and cured states. RESULTS: In the acetone/model resin system, maximum conversion occurred with 2.5-5.0M solvent. In the ethanol/model resin system, conversion peaked at 2.5M solvent. Above 5.0M solvent, conversion values declined rapidly for both solvents. A 13.0-M solution resulted in near 0% conversion for both solvents. At 2.5 and 5.0M acetone, conversions exceeded those of equivalent concentrations of the ethanol-based system. CONCLUSIONS: For both an acetone- and ethanol-solvated model resin system, conversion did not immediately decrease with addition of solvent, but instead increased over that of the model resin alone. At higher solvent content (greater than 2.5M ethanol and 5.0M acetone), conversion rapidly declined, with ethanol causing less conversion at equal-molar solvent concentrations.

Mathematical modeling of molar tooth preparations for complete crowns.

OBJECTIVES: This study used both cone frustum and right truncated pyramids mathematical methods to evaluate and characterize molar tooth surface area. Previous mathematical modeling studies evaluated only the total surface area. We attempted to analyze both the top surface and lateral surface areas. METHODS: The computations were performed according to the published formulas. The vertical heights of both models were assigned to be 3 and 4mm and the horizontal base width chosen to be 9 and 10mm for both models. Three total occlusal convergences: 10 degrees , 15 degrees , and 20 degrees were selected to be the tested parameters. RESULTS: The calculated data revealed that the top surface area represented a relatively large proportion of the total surface area in both models. We also found that the effect of increasing the total occlusal convergence has a much greater effect on the overall top surface area than the lateral surface and total surface areas. CONCLUSIONS: The models previously used to report and compare surface areas of prepared natural teeth were found to be overestimating the overall surface area. More complex configurations including two-plane reductions, anatomy of cusps and retentive features such as slots and grooves need to be included in future modeling protocols.

Sialolith characterization by scanning electron microscopy and X-ray photoelectron spectroscopy.

The objective of this study has been to characterize sialolith, a calcium phosphate deposit that develops in the human oral cavity, by high-resolution field emission scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The morphological and chemical data obtained helped in the determination of their formation mechanism in salivary glands. Sialoliths in the submandibular salivary glands may arise secondary to sialodenitis, but not via a luminal organic nidus. We believe this is the first study that characterizes a sialolith by XPS.

A Review of Hydroxapatite and its use as a Coating in Dental Implants.

At present, no standard manufacturing guideline exists for depositing hydroxyapatite (HA) on implant surfaces. Although animal and in vitro studies have reported on the benefits of using HA-coated implants as well as the risks of dissolution, these short-term studies did not demonstrate that the dissolution of the HA coating leads to a loss of implants. In addition, many in vivo and clinical studies did not include the chemical and structural characterization of the coatings, and thus comparisons between studies are difficult. In the clinics, the recommendation is that HA-coated screw implants be used for the anterior maxilla and posterior mandible where the bone depth exceeds 10 mm and when the cortical layer is thinner and spongiosia is less dense. In the posterior maxilla or when the cortical layer is very thin with low density, the use of HA-coated cylindrical implants is recommended. However, there are concerns for using HA-coated implants. The clinician needs to take into consideration the enhanced bacterial susceptibility of HA coatings compared with titanium implants. In addition, the clinician needs to consider the possible failure of HA coatings as a result of coating-substrate interfacial fracture. Finally, besides the surgical skills, it is also important that the clinical investigators be well versed with the materials characterization needed for HA-coated implants, the problems associated with the current HA coatings, and the indications for use. In addition, the correlation between well characterized coatings and their effect on bone formation rate and long-term implant success, coating-implant interfacial strength, and alternative superior coating process need to be investigated further.

Microtensile bond strength testing and failure analysis of hybrid and flowable composites.

PURPOSE: Few studies have been performed on the cohesive tensile strength of flowable resin composites and hybrids, or on the coupling strength of flowables to hybrid composites. Thus, the purpose of this study was to measure interfacial microtensile bond strengths between hybrid resin composite and flowable resin composite/compomer. MATERIALS AND METHODS: A polyvinyl siloxane mold was used to fabricate specimens for 9 groups, each consisting of 15 rectangular beams (2 x 2 x 20 mm). Flowable and hybrid resin composites and their paired couplings with each manufacturer's product line were tested. Materials include Heliomolarflow, Revolution, and Dyractflow as representative flowable resin composites and compomer. Heliomolar HB, Prodigy, and Esthet X were selected as representive hybrid resin composites. Resin specimens were cured for a total of 80 s and immersed in water for 7 days. A microspecimen former was used to trim rectangular specimens into specimens with a circular cross section (diameter = 1.0 mm) with a 2 mm gauge length. Specimens were subjected to tensile forces in a passive-gripping space mounted on a Vitrodyne machine. RESULTS: The results are expressed in MPa. Kruskal-Wallis one-way ANOVA on ranks demonstrated significant differences in microtensile bond strength among groups (p < 0.001). CONCLUSION: The cohesive tensile strength of resin composites were material dependent. Flowable and hybrid composites from the same manufacturer have comparable cohesive tensile strengths. The coupling strength of flowable/hybrid combinations were comparable to cohesive strength of the hybrid composites with the exception of Esthet X/Dyractflow, where the coupling was stronger than the cohesive strength of either resin composite alone.

Predictors of non-carious loss of cervical tooth tissues.

This Predictor Variables study is designed to determine which one of 11 factors evaluated may be correlated to Non-carious Loss of Cervical Tooth Tissues (NLCTT) using subjects with and without NLCTT. The ultimate objective is to successfully predict the path toward risky behaviors and reduce the incidence of NLCTT.

Standardized method to produce tetracycline-stained human molar teeth in vitro.

OBJECTIVE: This study tested the hypothesis that exposure of human molar teeth to tetracycline (TCN) derivatives in vitro results in tooth discoloration resembling the clinical presentation of TCN staining. METHOD AND MATERIALS: The effects of exposure of 20 extracted human molar teeth to distilled water, chlortetracycline, doxycycline, or minocycline were compared. The baseline color of each tooth was analyzed with a dental spectrophotometer. The pulp chambers were each filled with a TCN derivative solution and then sealed. The teeth were placed in a centrifuge tube and then centrifuged at 2800 rpm for 20 minutes. Color change was monitored weekly for 7 weeks. Digital images of the surfaces were recorded. For each specimen at every evaluation period, color change from baseline was calculated using Commission Internationale d'Eclairage (CIE) Delta E 2000 (deltae00). RESULTS: There was a significant association between the type of derivative used and deltae00, as well as between the evaluation period and deltae00. There was also a significant association between the interaction term, derivative x evaluation period, and deltae00. Results of the Holm-Sidak post hoc test demonstrated that all 3 TCN derivatives were associated with significantly larger deltae00 than the control group (P < or = .05). CONCLUSIONS: All 3 TCN derivative solutions produced significant color changes as time progressed. Different TCN derivatives produced a different L* (lightness), C* (chroma), and H* (hue), with minocycline behaving distinctly differently from chlortetracycline and doxycycline. The model could be used to study the underlying mechanisms of TCN staining as well as many aspects of vital tooth