Microcomputed tomography void analysis after cement cleanup methods.

STATEMENT OF PROBLEM: Cement at the restorative margin after implementation of the manufacturer's recommended procedure for cement cleanup has not been extensively evaluated. PURPOSE: The purpose of this in vitro study was to use microcomputed tomography (µCT) to evaluate the number, volume, and width of voids left at the margin when dental cement is cleaned during the cementation process as per 2 manufacturer-prescribed methods for cement cleanup by evaluating a self-adhesive resin cement and a resin-modified glass ionomer cement. MATERIAL AND METHODS: Twenty molar Ivorine Typodont prepared teeth were scanned, and lithium disilicate crowns were milled and cemented to the prepared teeth as per the manufacturer-recommended cementation process. Two methods of cement cleanup were performed: the excess cement was tack-polymerized with a polymerization light, or a delay of 3 minutes was used for the excess cement to reach partial polymerization, and the excess cement was removed with a sharp sickle scaler. These 2 methods of cement cleanup were performed with 2 cements: a resin-modified glass ionomer cement and a self-adhesive resin. Each specimen was then scanned with a µCT machine. The buccal margin of each specimen, from mesiobuccal line angle to distobuccal line angle, was examined, and the number, volume, and width of any voids remaining at the margin open to the environment were measured. For statistical analysis, the specimens were first grouped by method of cement cleanup and then grouped by cement type. The Wilcoxon ranked sum test was implemented because of the lack of a normal distribution and the heterogeneity of the data (α=.05). RESULTS: No statistically significant difference was found in the median number of voids, median volume of voids, or median width per void between the 2 cleanup methods, irrespective of cement type (P>.05). Significant differences were found in the median number of voids, median volume of voids, and median width per void when comparing cement types, irrespective of cement cleanup methods (P<.05). CONCLUSIONS: The choice of cement may be more important than the method of cement cleanup when considering voids left at the margin. Microcomputed tomography is an excellent nondestructive tool for volumetric measurements of voids at the margin.

Clinical performance of a modified Resin-Bonded fixed partial denture (Carolina bridge): A retrospective study.

OBJECTIVES: This research aims to retrospectively evaluate the clinical performance of Carolina bridge (CB) placed at a dental school. MATERIALS AND METHODS: Data were collected from the electronic patient record system. A follow-up letter was sent to the subjects' mailing address explaining the research purpose along with a questionnaire to assess their satisfaction with the treatment. A phone interview was performed to assess patient satisfaction, function, and choice of permanent restoration. Finally, a clinical exam was conducted for patients that agreed to come for a follow-up and still had their CBs. RESULTS: Twenty-three patients with 26 resin-bonded CBs met the inclusion criteria. All patients who did the phone interview reported to be very satisfied with the treatment. Most chose to keep the CB as definitive treatment and not to move forward with implant therapy. According to the number of rebonding needed to maintain the CB, the types of survival were analyzed as 42.3% complete survival (no rebonding needed), 26.9% functional survival (rebonded once), 23.1% survival with multiple rebondings, 7.6% failure. CONCLUSION: The performance of CBs revealed highly acceptable performance with high-patient satisfaction. CLINICAL SIGNIFICANCE: Carolina ridge is an esthetic and conservative interim treatment option that can be utilized in favorable clinical situations.

Monolithic Zirconia Partial Coverage Restorations: An In Vitro Mastication Simulation Study.

PURPOSE: To evaluate the survival rate (fatigue resistance), bonding efficiency and marginal integrity of monolithic zirconia partial and full coverage single restorations adhesively bonded to the tooth structure using air-particle abrasion, a primer with 10-methacryloyloxydecyl dihydrogen phosphate and a composite-resin cement (APC) protocol. MATERIALS AND METHODS: Extracted human premolars (N = 32) were randomly divided into four groups of eight specimens each. Premolars were prepared for the following restorations: full crown (group 1, control), mesial-occlusal-distal-facial onlay (MODF, group 2) preserving 2 mm facio-lingual functional cusp width, mesial-occlusal-distal-lingual onlay (MODL, group 3) preserving 2 mm facio-lingual nonfunctional cusp width, mesial-occlusal-distal-buccal-lingual onlay (MODBL, group 4), overlay preparation. All restorations were milled from monolithic 3 mol% yttria (3Y) zirconia blocks (ZirCad, A1 LT, Ivoclar Vivadent) with CAD/CAM software presets at minimum occlusal and axial thicknesses of 1 mm. The intaglio surface of the restorations was air-particle abraded (50 µm Al2 O3 , 2-Bar pressure, 15 s, 10 mm distance) and primed. An adhesive cement system was used to bond the restorations. Each group was subjected to thermomechanical loading for 1.2 million cycles (force = 70 N, 1.4 Hz) with simultaneous thermocycling (5-55°C, 30 s dwell time) using a mastication simulator. All specimens were examined under scanning electron microscope (SEM) analysis (30, 100, and 150×) to evaluate cracks and marginal defects. Fracture of restoration and/or fracture within tooth structure, and debonding were considered modes of failure. RESULTS: One specimen from group 2 debonded at 632,000 cycles. None of the specimens failed due to fracture. SEM analysis at 30× indicated marginal integrity issue of the remaining seven intact specimens of group 2 in the area of antagonist contact. No specimens from group 1, 3, and 4 demonstrated marginal integrity issue at 30×. None of the specimens demonstrated any microcrack at 100× and150×. CONCLUSIONS: Due to its fatigue resistance, 3Y-zirconia is a viable option for partial and full coverage single restorations. Following a strict bonding protocol, zirconia demonstrated durable adhesion to the tooth structure. Occlusal contact on restoration margins should be avoided.

Management of amelogenesis imperfecta in an adult patient: a short review and clinical report.

Objective This clinical report aims to share with general practitioners a conservative approach to treat patients with amelogenesis imperfecta (AI).Clinical considerations In relatively young patients, a conservative treatment approach is essential in order to maintain the vitality of the teeth and provide successful outcomes. In this clinical report, the diagnoses and treatment plan of an 18-year-old male patient diagnosed with AI is discussed. Composite rehabilitation followed by orthodontic treatment was considered the most conservative treatment approach for this patient.Conclusion Bonding to well-mineralised enamel can be a predictable and successful treatment approach for young patients diagnosed with AI.

Potential oral health effects of e-cigarettes and vaping: A review and case reports.

OBJECTIVE: In this article, the potential oral health consequences of vaping are described. While most dentists are likely aware of the potential serious health effects involved with vaping, the aim of this article was to raise awareness on identified oral health consequences. CLINICAL CONSIDERATIONS: Three patients presented to one dental practice with unusual patterns of dental caries, and all three admitted to regular vaping. Vaping components include propylene glycol, glycerin, nicotine, and flavors, which contain sucrose, sucralose, and ethyl maltol. The vapor produced by vaping devices is thick and viscous and much of it is retained on oral tissues. There are over 10 000 different vaping liquids, including some that contain tetrahydrocannabinol (THC) and vitamin E acetate. Vaping clearly has the potential to negatively affect general health, periodontal health, and accelerate the development of caries. There is also evidence that teenagers are being attracted to vaping in astonishing numbers. CONCLUSIONS: The general health consequences of vaping have received considerable attention in the national media. There is much to be learned about the consequences of this behavior. There are also potential serious oral health consequences to vaping. It is likely that the composition of certain vaping solutions may make them more harmful than others CLINICAL SIGNIFICANCE: It is important that dental professionals are made aware of the potential problems related to vaping. Initial reports show that the effect of e-cigarettes on periodontal tissues is similar to that of conventional cigarettes. Some vaping formulations may be highly cariogenic, especially those with sweet flavors, which are used to attract young people. Patients should be routinely questioned about their vaping habits in the medical-dental history.

Fracture load of two thicknesses of different zirconia types after fatiguing and thermocycling.

STATEMENT OF PROBLEM: A direct relationship has been reported between yttria concentration and translucency in zirconia restorations. However, increased yttria concentration also increases the cubic phase of the zirconia, which reduces its strength. The effect of increased yttria content on the fracture resistance of zirconia as a function of material thickness after fatigue testing requires evaluation. PURPOSE: The purpose of this in vitro study was to use the biaxial flexural test to evaluate the effect of yttria concentration on the mean fracture load (N) before and after fatiguing and thermocycling as a function of zirconia thickness. MATERIAL AND METHODS: Disk-shaped specimens of 5 mol% yttria partially stabilized zirconia (5Y-PSZ, BruxZir Anterior Solid Zirconia) and 3 mol% yttria partially stabilized zirconia (3Y-PSZ, BruxZir Shaded Zirconia) were prepared to thicknesses of 1.2 and 0.7 mm. For each thickness, the biaxial flexural test was used to measure the fracture load (N) before and after fatigue testing, with 1.2 million cycles at a 110-N load and simultaneous thermocycling at 5 °C to 55 °C (n=20). The data were analyzed by repeated-measures ANOVA (α=.05). RESULTS: Yttria concentration, thickness, and exposure to fatiguing had a statistically significant effect on the mean biaxial flexural load (yttria concentration: P<.001; thickness: P<.001; fatiguing: P=.004 for the 3Y-PSZ). One of the major findings in this study was that 30% of the 1.2-mm-thick 5Y-PSZ specimens and 80% of the 0.7-mm-thick 5Y-PSZ specimens fractured during fatiguing. All specimens of the 3Y-PSZ groups survived the fatiguing protocol. The 3Y-PSZ groups had statistically significant higher flexural loads than the 5Y-PSZ groups. The 1.2-mm thickness groups had statistically significant higher flexural loads than the 0.7-mm thickness groups. CONCLUSIONS: Yttria concentration had a significant effect on the strength of zirconia. 5Y-PSZ was considerably less resistant to fracture before and after fatigue testing than 3Y-PSZ. Decreasing the thickness of zirconia reduces its fracture resistance, regardless of the zirconia type.

The segmental impression technique: A straightforward solution to a difficult problem.

Trying to capture all the details of multiple teeth preparation in one impression is challenging. Techniques have been suggested to extend the working time of an impression material. This article describes a segmental impression technique to accurately capture all the preparation margins while allowing additional impression-making time.

Effect of masticatory simulation on the translucency of different types of dental zirconia.

STATEMENT OF PROBLEM: Translucent zirconia has been marketed to dentists seeking to provide esthetic monolithic dental restorations. Evidence on differences in translucency between recently introduced translucent zirconia and conventional zirconia before and after fatigue testing with thermocycling is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effect of fatiguing and thermocycling on the translucency of 5 mol% yttria partially stabilized zirconia (5Y-PSZ) and 3 mol% yttria partially stabilized zirconia (3Y-PSZ) at clinically relevant thicknesses. MATERIAL AND METHODS: Translucent zirconia (BruxZir Anterior Solid Zirconia [5Y-PSZ]) and conventional zirconia (BruxZir Shaded Zirconia [3Y-PSZ]) were evaluated. Disk-shaped specimens were prepared to 0.7-mm and 1.2-mm thicknesses for each zirconia type. Four groups (n=10/group) were evaluated. Translucency parameter (TP), contrast ratio (CR), and light blockage percentage (Lb%) were recorded by using an integrating sphere spectrophotometer before and after fatiguing (1.2 million cycles at 110-N load with simultaneous thermocycling at 5 °C to 55 °C). Data were analyzed by repeated-measures analysis of variance for statistical significance (α=.05). CR values were compared with the reported 0.06 translucency perception threshold of the human eye. RESULTS: A statistically significant difference was found in TP, CR, and Lb% between 5Y-PSZ and 3Y-PSZ (P<.001). Thickness had a statistically significant effect on TP, CR, and Lb% (P<.05). The 0.7-mm thickness groups were more translucent and had lower Lb% than the 1.2-mm thickness groups (P<.001). Baseline ranking from most to least translucent according to TP and CR measurements was as follows: 5Y-PSZ (0.7 mm), 3Y-PSZ (0.7 mm), 5Y-PSZ (1.2 mm), and 3Y-PSZ (1.2 mm). Lb% was 64% at the 1.2-mm and 56% at the 0.7-mm thickness in the 3Y-PSZ groups. Lb% was 61% at the 1.2-mm and 53% at the 0.7-mm thickness in the 5Y-PSZ groups. None of the groups, before and after fatiguing, had a CR value exceeding the clinically perceivable 0.06 translucency perception threshold value. CONCLUSIONS: Translucent (5Y-PSZ) and conventional (3Y-PSZ) zirconias evaluated in this study displayed degrees of translucency that were inversely related to the zirconia thickness. 5Y-PSZ was more translucent and blocked less light than 3Y-PSZ, but this difference may not be perceivable to the human eye. Both 5Y-PSZ and 3Y-PSZ were optically stable after fatiguing and thermocycling.

Education About Dental Erosion in U.S. and Canadian Dental Schools.

Dental erosion (DE) is a well-accepted multifactorial form of tooth wear involving acids. Due to its irreversible nature, recognizing the early signs is important to develop appropriate preventive strategies. However, its place in dental curricula remains unclear. Consensus has not been established regarding the integration of erosive tooth wear into core cariology curricula in North America. The extent to which DE is taught is questionable since etiology, risk assessment, and management are not all the same as for dental caries. The aim of this study was to survey U.S. and Canadian dental schools regarding their teaching of DE. Email invitations were sent to deans, chairs, and selected faculty members at all 76 U.S. and Canadian dental schools in 2016, asking them to either respond or forward the survey-link provided to the appropriate person in their school. Responses from the same school were combined for analysis. Respondents from 59 schools (77.6% response rate) responded to the survey, and all of them confirmed the inclusion of DE in their curricula. However, only 15.3% of respondents identified correctly all the clinical signs of DE. Although management through behavioral intervention was prioritized, diet analysis was often not a clinical requirement, and 45.8% of respondents did not teach any type of tooth wear index for monitoring. This study concluded that DE has a place in dental curricula, but whether this topic is adequately covered is questionable. There is a need to establish clearer topics and requirements emphasizing the diagnosis and management of DE, potentially in cariology curricula.

Teaching Silver Diamine Fluoride in U.S. Dental Schools' Predoctoral Curricula.

Silver diamine fluoride (SDF), a low-cost topical agent used in many countries to arrest dental caries, was cleared as a desensitizing agent by the Food & Drug Administration for the U.S. market in 2014. The aim of this study was to survey U.S. dental schools regarding their teaching of SDF. Email invitations were sent to all accredited U.S. predoctoral dental education programs (n=66) in September 2016. Deans, chairs, and selected faculty members were asked to respond or forward the survey-link provided to the appropriate person in their school. Under the assumption that some respondents from the same school were unaware of SDF implementation across departments, multiple responses from the same school were collapsed for analysis. A total of 62 schools (94% response rate) responded to the survey, and 67.7% of them reported that SDF was part of their curricula. There was a wide variation across dental schools' teaching about SDF indications and protocols of application. All but one school consistently agreed on using SDF for arresting caries on primary teeth. Only 18 respondents were able to confirm if there was an existing protocol at their school for the use of SDF. When re-application after initially arresting caries with SDF was taught, 50% of respondents advocated 2×/year re-application. Schools not teaching SDF (n=20) planned on including it in their curricula in the future. These findings suggest that, with the use of SDF increasing rapidly in the U.S. and its adoption in most dental schools, there is a need for the development of standardized evidence-based protocols.

The erosive potential of additive artificial flavoring in bottled water.

Acidic beverage consumption is a well-recognized contributor to extrinsic dental erosion. Although the pH values of some commercially available bottled waters are below neutral pH, water is still considered to be a safe and healthy choice. Artificial flavoring liquids or powders, known as water enhancers (WEs), have been introduced to the market to modify the taste of water. The purposes of the present study were to measure the pH and titratable acidity of WEs and to perform gravimetric analysis of teeth immersed in solutions of WEs mixed with different brands of bottled water in order to determine the erosive potential in vitro. The pH and titratable acidity using 0.1M sodium hydroxide were calculated for 7 brands of WEs added to 3 brands of bottled water, which had different initial pH values. Extracted human molar teeth were submerged in each combination of solutions for gravimetric analysis. Distilled water was used as the positive control and citric acid as the negative control. Data were analyzed with 2-way analysis of variance and post hoc Tukey-Kramer testing (P = 0.05). The pH value (2.9-3.0) and titratable acidity (32.2-35.3 mmol/L hydroxide) of all of the experimental solutions were considered acidic, regardless of the WE brand. Average tooth structure loss after 1 month of immersion in the solutions was 4%, and surface changes were consistent with erosive dissolution. The results showed that adding a WE to water significantly increases the potential for dental erosion. The high content of citric acid in WEs is believed to be the cause. Patients should be advised to use WEs with caution.

The quality of fixed prosthodontic impressions: An assessment of crown and bridge impressions received at commercial laboratories.

BACKGROUND: The authors evaluated and quantified clinically detectable errors commonly seen in impressions sent to commercial laboratories and determined possible relationships between finish line errors and other factors involved. METHODS: The authors visited 3 large and 1 small commercial dental laboratories over a 12-month period. Three calibrated examiners evaluated the impressions. The examiners evaluated all impressions for errors by using ×2.5 magnification loupes under ambient room lighting without the aid of additional illumination. RESULTS: The authors evaluated 1,157 impressions; 86% of the examined impressions had at least 1 detectable error, and 55% of the noted errors were critical errors pertaining to the finish line. The largest single error categories evaluated were tissue over the finish line (49.09%), lack of unprepared stops in dual-arch impressions (25.63%), pressure of the tray on the soft tissue (25.06%), and void at the finish line (24.38%). The factors blood on the impression (odds ratio, 2.31; P < .001) and tray type (odds ratio, 1.68; P < .001) were associated significantly with finish line errors. CONCLUSIONS: Marginal discrepancies made up the largest category of error noted in impressions evaluated. The authors noted an increase in errors at the finish line with dual-arch impression techniques and in the presence of blood. PRACTICAL IMPLICATIONS: Dentists have ethical, moral, and legal obligations bestowed on them by the profession and need to evaluate critically the work they send to laboratories. The authors strongly recommend an improvement in technique and reviewing of all impressions and working casts.

Survey of dentists to determine contemporary use of endodontic posts.

STATEMENT OF PROBLEM: Although the scientific literature provides sound decision-making tools for the restoration of endodontically treated teeth, dentists have different opinions on the rationale for the use of endodontic posts (dowels) and selection of post systems. The decision to place a post is at times contrary to the literature. Updated information on the treatment of endodontically treated teeth among general dentists is lacking. PURPOSE: The purpose of this survey was to gain insight into the rationale for choice of endodontic posts and the different endodontic post systems currently used by dental practitioners. Post and core restorations distribute stress and replace missing tooth structure in endodontically treated teeth. Guidelines exist to help select post systems. With the advent of new materials, prefabricated posts have gained popularity among dentists. However, cast-metal post-and-core systems are still considered the gold standard. MATERIAL AND METHODS: Surveys were distributed to dentists attending continuing education meetings in the United States, Canada, Scotland, Ireland, and Greece. The questions addressed years of practice, specialty training, and brand, type, shape, and material of the endodontic post systems used. RESULTS: Descriptive statistical analysis was used to assess the percentage of respondents. Ninety-two percent of the participants were general practitioners with 25.94 ±13.35 years of experience. The majority agreed upon using endodontic posts when insufficient coronal tooth structure remains and for stress distribution. Passive, parallel posts were the most commonly reported type and shape. With regard to post material, fiber posts were the most frequently used (72.2%), followed by prefabricated alloys (38.6%), cast-metal posts (33.9%), prefabricated titanium posts (30.1%), and stainless-steel posts (21.7%). For cementation, resin-modified glass ionomer (40%) was most frequently used, followed by self-adhesive resin (29.6%). CONCLUSIONS: The majority of the practitioners used fiber posts. This may be because, in terms of fracture, they compare favorably with cast-metal post and core, although little evidence in the literature validates this claim.

Gingival displacement: Survey results of dentists' practice procedures.

STATEMENT OF PROBLEM: A high percentage of fixed prosthodontic restorations require a subgingival margin placement, which requires the practice of gingival displacement or a deflection procedure to replicate the margins in impression. PURPOSE: The purpose of this study was to learn the different gingival displacement techniques that are currently used by dentists in their practice and to compare the current concepts of gingival displacement with previously published articles. MATERIALS AND METHODS: A survey of questions pertaining to gingival deflection methods was distributed as part of continuing education (CE) course material to dentists attending CE meetings in 7 states in the U.S. and 1 Canadian province. Question topics included initial patient assessment procedures, gingival displacement methods, dentist's knowledge and assessment of systemic manifestations, and brand names of materials used. RESULTS: Ninety-four percent of the participants were general practitioners with 24.11 ± 12.5 years of experience. Ninety-two percent used gingival displacement cords, while 20.2% used a soft tissue laser and 32% used electrosurgery as an adjunct. Sixty percent of the dentists used displacement cords impregnated with a medicament. Of the preimpregnated cords, 29% were impregnated with epinephrine, 13% with aluminum chloride, and 18% with aluminum potassium sulfate. CONCLUSION: The study showed a steady decrease compared with results of previously published articles in the use of epinephrine as a gingival deflection medicament.

Remineralization effect of CPP-ACP and fluoride for white spot lesions in vitro.

OBJECTIVES: This in vitro study compared the remineralization effect on white spot lesions of casein phosphopeptide-amorphous calcium phosphate crème, or CPP-ACP (MI Paste™), 1.1% NaF dentifrice containing 5000ppm of fluoride (ControlRX™), or CPP-ACP crème with 900ppm of fluoride (MI Paste Plus™) with that of a control. METHODS: Artificial white spot lesions were created on smooth enamel surfaces of sound molars using a previously reported demineralization model. Specimens were randomly assigned to four treatments (n=35) with a pH-cycling model over 30 days: Control (no treatment); MI Paste (10% CPP-ACP crème); F5000 (1.1% NaF dentifrice); or MI Paste Plus (10% CPP-ACP plus 900ppm fluoride crème). Products were applied following manufacturers' directions. Changes in mean lesion depth expressed by percent fluorescence loss (ΔF%), and lesion area (mm(2)) from baseline to after treatment were measured with light-induced fluorescence (QLF). Mean values of each parameter were compared between groups (p<0.05). RESULTS: The remineralization pattern for the F5000 group was unique with marked initial remineralization during the first 10 days and little subsequent change. Based on mean lesion area, the F5000 demonstrated greater remineralization than Control, MI Paste and MI Paste Plus groups. Based on mean fluorescence loss, the F5000 group showed improved remineralization relative to MI Paste Plus, but did not differ statistically from the Control at the end of 30 days. CONCLUSIONS: The 1.1% NaF dentifrice demonstrated overall greater remineralization ability than 10% CPP-ACP crème. However, the 1.1% NaF dentifrice was only as effective as the Control to reduce fluorescence loss. CLINICAL SIGNIFICANCE: This study showed that a 1.1% NaF dentifrice (5000ppm) demonstrated greater remineralization ability than the CPP-ACP topical tooth crème and that the addition of fluoride to its formulation seems to enhance remineralization. Saliva also has the ability to exert an important remineralization effect over time.