The objectives of this research were to (1) quantify the discordance between the caries lesion depth at which dentists restored initial lesions during a clinical study (“actual depth”) and the lesion depth that they reported during a hypothetical clinical scenario (“reported depth”); (2) test the hypothesis that certain practitioner, practice, patient, and caries lesion characteristics are significantly associated with this discordance.
Practitioner-investigators who perform restorative dentistry in their practices completed an enrollment questionnaire and participated in two consecutive studies on caries diagnosis and treatment. The first study was a survey asking about caries treatment. The second study collected data on restorations placed in routine clinical practice due to caries in patients over 19 years of age on occlusal surfaces only or proximal surfaces only. We report results on 2691 restorations placed by 205 dentists in 1930 patients with complete data.
Discordance between actual depth and reported depth occurred in only about 2% of the restorations done due to proximal caries, but about 49% of the restorations done due to occlusal caries. Practice type, restorative material used and the diagnostic methods used were significantly associated with discordance.
Dentists frequently restored occlusal caries at a shallower depth as compared to their reported depth, but the discordance was very small for proximal lesions. Discordance for occlusal caries was more common when radiographs were not taken or if a resin restoration was placed.
Caries; threshold; restoration; remineralization; decision making
To investigate the correlation of the chemical interaction between model self-etching adhesives and dentin with the degree of conversion (DC) of the adhesives.
The model self-etching adhesives contained bis[2-methacryloyloxy)ethyl] phosphate (2MP) and 2-hydroxyethyl methacrylate (HEMA) with a mass ratio of 1/1, and 0-40% water contents, respectively. The adhesives were applied either onto the prepared dentin surface or unreactive substrates (such as glass slides), agitated for 15s, then light-cured for 40s. The DCs of the adhesives were determined using micro-Raman spectral and mapping analysis.
The DCs of the adhesives cured on the dentin substrate were found to be significantly higher than those on the unreactive glass substrate. Moreover, the DCs of the adhesives displayed a decreasing trend as the distance from the dentin surface became greater. The chemical interaction of the acidic 2MP/HEMA adhesives with the mineral apatite in dentin was proposed to play a significant role for the observations. The chemical interaction could be validated by the spectral comparison in the phosphate regions of 1100 cm−1 and 960 cm−1 in the Raman spectra. The results also revealed a notable influence of water content on the DC of adhesives. The DCs of the adhesive at 10% water content exhibited the highest DC level for both substrates.
Interaction with dentin dramatically improved the degree of conversion of self-etching adhesives. Our ability to chemically characterize the a/d interface including in situ detection of the DC distribution is very important in understanding self-etching adhesive bonding under in vivo conditions.
Self-etching; dentin; micro-Raman spectroscopy; photo-polymerization; degree of conversion
To compare fatigue failure modes and reliability of hand-veneered and over-pressed implant-supported three-unit zirconium-oxide fixed-dental-prostheses(FDPs).
Sixty-four custom-made zirconium-oxide abutments (n=32/group) and thirty-two zirconium-oxide FDP-frameworks were CAD/CAM manufactured. Frameworks were veneered with hand-built up or over-pressed porcelain (n=16/group). Step-stress-accelerated-life-testing (SSALT) was performed in water applying a distributed contact load at the buccal cusp-pontic-area. Post failure examinations were carried out using optical (polarized-reflected-light) and scanning electron microscopy (SEM) to visualize crack propagation and failure modes. Reliability was compared using cumulative-damage step-stress analysis (Alta-7-Pro, Reliasoft).
Crack propagation was observed in the veneering porcelain during fatigue. The majority of zirconium-oxide FDPs demonstrated porcelain chipping as the dominant failure mode. Nevertheless, fracture of the zirconium-oxide frameworks was also observed. Over-pressed FDPs failed earlier at a mean failure load of 696 ± 149 N relative to hand-veneered at 882 ± 61 N (profile I). Weibull-stress-number of cycles-unreliability-curves were generated. The reliability (2-sided at 90% confidence bounds) for a 400N load at 100K cycles indicated values of 0.84 (0.98-0.24) for the hand-veneered FDPs and 0.50 (0.82-0.09) for their over-pressed counterparts.
Both zirconium-oxide FDP systems were resistant under accelerated-life-time-testing. Over-pressed specimens were more susceptible to fatigue loading with earlier veneer chipping.
zirconium-oxide; fatigue; chipping; Weibull-reliability; fixed-partial-denture; implants; over-pressed; hand-veneered; core; porcelain
Matrix metalloproteinases play an important role during the initial process of enamel development and therefore may play a role in caries.
To evaluate the association between MMP20 and caries experience in Brazilian children.
Eligible unrelated children with or without caries were evaluated using a cohort design. Demographic data and oral health habits were obtained though a questionnaire. Caries data was collected by clinical examination. Genotyping of the selected polymorphism was carried out by real-time PCR from genomic DNA. Allele and genotype frequencies were compared between groups with distinct caries experience and oral health habits.
Of 388 subjects, 161 were caries free children. There were no differences between caries levels and genotype distribution in the total cohort. When ethnic background was considered, differences in genotype distribution were observed in caries free children versus children with caries in Caucasians (p=0.03). Differences could also be seen when poor oral hygiene was used to stratify the analysis (p=0.02). Regression analysis, adjusted for genotype and ethnicity, confirmed that ingestion of sweets between meals increases the risk of presenting carious lesions (p=0.00001; OR=2.33; 95%CI 1.53–3.54).
Variation in MMP20 may be associated with caries experience mainly in Caucasian subjects with poor oral health habits.
dental caries; matrix metalloproteinases; enamelysin; polymorphisms; SNPs; genetic susceptibility
The lack of durability in resin–dentine bonds led to the use of chlorhexidine as MMP-inhibitor to prevent the degradation of hybrid layers. Biomimetic remineralisation is a concept-proven approach in preventing the degradation of resin–dentine bonds. The purpose of this study is to examine the integrity of aged resin–dentine interfaces created with a nanofiller-containing etch-and-rinse adhesive after the application of these two approaches.
The more established MMP-inhibition approach was examined using a parallel in vivo and in vitro ageing design to facilitate comparison with the biomimetic remineralisation approach using an in vitro ageing design. Specimens bonded without chlorhexidine exhibited extensive degradation of the hybrid layer after 12 months of in vivo ageing.
Dissolution of nanofillers could be seen within a water-rich zone within the adhesive layer. Although specimens bonded with chlorhexidine exhibited intact hybrid layers, water-rich regions remained in those hybrid layers and degradation of nanofillers occurred within the adhesive layer. Specimens subjected to in vitro biomimetic remineralisation followed by in vitro ageing demonstrated intrafibrillar collagen remineralisation within hybrid layers and deposition of mineral nanocrystals in nanovoids within the adhesive.
The impact was realized by understanding the lack of an inherent mechanism to remove water from resin–dentine interfaces as the critical barrier to progress in bonding with the etch-and-rinse technique. The experimental biomimetic remineralisation strategy offers a creative solution for incorporating a progressive hydration mechanism to achieve this goal, which warrants its translation into a clinically applicable technique.
Ageing; Biomimetic remineralisation; Chlorhexidine; Degradation; Hybrid layer; Matrix metalloproteinase
To (1) quantify the diagnostic techniques used by Dental Practice-Based Research Network (DPBRN) dentists before they decide to treat primary caries lesions surgically and (2) examine whether certain dentist, practice, and patient characteristics are associated with their use.
A total of 228 DPBRN dentists recorded information on 5,676 consecutive restorations inserted due to primary caries lesions on 3,751 patients. Practitioner-investigators placed a mean of 24.9 (SD=12.4) restorations. Lesions were categorized as posterior proximal, anterior proximal, posterior occlusal, posterior smooth, or anterior smooth. Techniques used to diagnose the lesion were categorized as clinical assessment, radiographs, and/or optical. Statistical analysis utilized generalized mixed-model ANOVA to account for the hierarchical structure of the data.
By lesion category, the diagnostic technique combinations used most frequently were clinical assessment plus radiographs for posterior proximal (47%), clinical assessment for anterior proximal (51%), clinical assessment for posterior occlusal (46%), clinical assessment for posterior smooth (77%), and clinical assessment for anterior smooth (80%). Diagnostic technique was significantly associated with lesion category after adjusting for clustering in dentists (p<0.0001).
These results — obtained during actual clinical procedures rather than from questionnaire-based hypothetical scenarios — quantified the diagnostic techniques most commonly used during the actual delivery of routine restorative care. Diagnostic technique varied by lesion category and with certain practice and patient characteristics.
Dental caries; dentists’ practice patterns; diagnostic techniques and procedures
To study the plasma treatment effects on deactivation effectiveness of oral bacteria.
A low temperature atmospheric argon plasma brush were used to study the oral bacterial deactivation effects in terms of plasma conditions, plasma exposure time, and bacterial supporting media. Oral bacteria of Streptococcus mutans and Lactobacillus acidophilus with an initial bacterial population density between 1.0 × 108 and 5.0 × 108 cfu/ml were seeded on various media and their survivability with plasma exposure was examined. Scanning electron microscopy was used to examine the morphological changes of the plasma treated bacteria. Optical absorption was used to determine the leakage of intracellular proteins and DNAs of the plasma treated bacteria.
The experimental data indicated that the argon atmospheric plasma brush was very effective in deactivating oral bacteria. The plasma exposure time for a 99.9999% cell reduction was less than 15 seconds for S. mutans and within 5 minutes for L. acidophilus. It was found that the plasma deactivation efficiency was also dependent on the bacterial supporting media. With plasma exposure, significant damages to bacterial cell structures were observed with both bacterium species. Leakage of intracellular proteins and DNAs after plasma exposure was observed through monitoring the absorbance peaks at wavelengths of 280nm and 260nm, respectively.
The experimental results from this study indicated that low temperature atmospheric plasma treatment was very effective in deactivation of oral bacteria and could be a promising technique in various dental clinical applications such as bacterial disinfection and caries early prevention, etc.
atmospheric gas plasmas; glow discharge; oral bacteria; sterilization
Contemporary methods of dentin bonding could create hybrid layers (HLs) containing voids and exposed, demineralized collagen fibers. Proanthocyanidins (PA) have been shown to crosslink and strengthen demineralized dentin collagen, but their effects on collagen degradation within the HL have not been widely studied. The purpose of this study was to compare the morphological differences of HLs created by BisGMA/HEMA model adhesives with and without the addition of grape seed extract PA under conditions of enzymatic collagen degradation.
Model adhesives formulated with and without 5% PA were bonded to the acid etched dentin. Five-μm-thick sections cut from the bonded specimens were stained with Goldner’s trichrome. The specimens were then exposed to 0.1% collagenase solution for zero, one, or six days. Following collagenase treatment, the specimens were analyzed with SEM/TEM.
Staining did not reveal a difference in the HLs created with the two adhesives. SEM showed the presence of intact collagen fibrils in all collagenase treatment conditions for specimens bonded with adhesive containing PA. These integral collagen fibrils were not observed in the specimens bonded with adhesive without PA after the same collagenase treatment. TEM confirmed that the specimens containing PA still showed normal collagen fibril organization and dimensions after treatment with collagenase solution. In contrast, disorganized collagen fibrils in the interfacial zone lacked the typical cross-banding of normal collagen after collagenase treatment for specimens without PA.
The presence of grape seed extract PA in dental adhesives may inhibit the biodegradation of unprotected collagen fibrils within the HL.
collagen crosslinking; adhesive/dentin interface; proanthocyanidins; bonding durability; collagenase
The aim of this pilot study was to investigate the anticaries activity of a nanoemulsion composed of soybean oil, water, Triton X-100 and cetylpyridinium chloride.
Tooth blocks (3 mm length × 3 mm width × 2 mm thickness) were cut from smooth surfaces of selected molar teeth using a water-cooled diamond wire saw. The blocks were randomly assigned to three experimental groups, (A) nanoemulsion, (B) 0.12% chlorhexidine gluconate, and (C) no treatment. The formation of dental caries in human tooth enamel was tested using a continuous flow dual-organism (Streptococcus mutans and Lactobacillus casei), biofilm model, which acts as an artificial mouth and simulates the biological and physiological activities observed within the oral environment. Experimental groups A and B were treated with their respective solutions once daily for 30 seconds on each occasion, while group C received no treatment. 10% sucrose was supplied every 6 hours for 6 minutes to simulate meals and pH cycling. The experiment lasted for 5 days, and the tooth blocks were harvested and processed for demineralization assessment using transverse microradiography (TMR).
For both lesion depth and mineral loss, statistical analysis indicated that Emulsion was significantly lower than Control and Chlorhexidine, and Chlorhexidine was significantly lower than Control.
We conclude that cetylpyridinium-containing nanoemulsions appear to present a feasible means of preventing the occurrence of early caries.
artificial caries; nanoemulsion; artificial mouth; transverse microradiography (TMR)
A sequential topical application of calcium and fluoride-phosphate solutions was reported to occlude open dentin tubules, mainly with fluoroapatite precipitates by a rapid ionic reaction, and to be effective at treating dentin hypersensitivity. However, its ability to reduce dentin permeability (Lp) is unknown. The aim of this in vitro study was to evaluate the effect of this treatment on Lp.
Nine extracted human third molars were sectioned transversely to obtain 0.5mm-thick discs, which were then etched and rinsed. Aqueous solutions of 5% (w/w) disodium phosphate containing 0.3% (w/w) sodium fluoride (A) and 10% (w/w) calcium chloride (B) were prepared. The sequential application of the A&B solutions was repeated three times on each disc, which was then rinsed with distilled water. The Lp of the discs was measured before and after the application using a modified Pashley’s fluid flow measuring system. The differences in the Lp values between the conditions before and after the solution applications were analyzed using a generalized estimating equation method and paired t-test. Scanning Electron Microscopy (SEM) was used to observe the dentin surfaces.
All nine discs consistently indicated reduced Lp following the application of the A&B solutions. There was a significant decrease in the mean Lp [µL/(cm2·sec·cmH2O)] from baseline (−0.27±0.25, p=0.011). Overall, an average decrease of 34% Lp occurred after the application of the A&B solutions. SEM observation indicated that the reaction products covered the entire dentin disc surface.
The application of the A&B solutions was effective at reducing the Lp of the dentin discs.
Dentin hypersensitivity; Desensitizing agents; Dentin permeability; Sequential application; Disodium phosphate; Sodium fluoride; Calcium chloride; Dentin tubules
Recent literature suggests that the scalloped structure of the dentino-enamel junction (DEJ) is critical for DEJ stability. Aim of our study was to see if there are differences in scallop size and shape with tooth type.
Enamel of extracted permanent human teeth was demineralised using EDTA. After fixation and dehydration the scallops of the DEJ were investigated in a scanning electron microscope. Scallop area and shape (circularity) were measured for molars, premolars, canines and incisors.
Scallop area showed main effects for tooth type and specimen, while, due to high variability in third molars, there was also an interaction effect (repeated measures two-way ANOVA, p < 0.05). Differences between tooth types were statistically significant, suggesting that posterior teeth showed larger scallops compared to anterior teeth. Differences in shape (circularity) were not statistically significant.
Our results suggest that teeth which are subject to higher masticatory loads (posterior teeth) show larger and more pronounced scallops. These findings might be of interest for improving other interfaces joining dissimilar materials.
dentino-enamel junction; interface; tooth structure; biomimetic model; teeth; scanning electron microscopy
The effects of interactions between cross-linking proanthocyanidins (PA) in polar solvents and type-I collagen of demineralized dentin was investigated.
Three PA-rich extracts, two from grape seed (GSEP and GSES) and one from cocoa (COE), were dissolved (water, ethanol:water and acetone:water) and analyzed for their ability to increase the modulus of elasticity of demineralized dentin. Sound dentin beams (0.5 X 1.7 X 7 mm) were fully demineralized and divided into 12 groups according to the type of cross-linking agent and solvents used. Specimens were immersed in the respective solutions and tested at baseline, 10, 30, 60, 120 and 240 min.
The elastic modulus (EM) of dentin was significantly increased by the PA treatment regardless of time (p<0.05 for all times). The extracts showed different solubility in different solvents. GSEP showed the highest increase in EM when diluted in distilled water and acetone at all exposure times. Both GSEs showed superior results when diluted in distilled water and after 4 hours of treatment, while COE produced strongest enhancement when dissolved in ethanol:water.
The results indicates that herbal extraction process and other pharmacognostic parameters have an important influence on extract solubility as well as constitution and, consequently, on the PA-dentin matrix interaction.
Dentin collagen; Cross-linkers; Polar systems; Proanthocyanidin; Hansen solubility parameters
Our objective was to compare the physiochemical properties and erosion potentials between beverages available in the UK and the US.
The physiochemical properties (pH, titratable acidity and fluoride concentration) and erosion potential on enamel surfaces of beverages available in the UK were compared to similar beverages from the US. Enamel windows were exposed to beverages for 25 hours. Teeth were sectioned through the windows, and lesion depths were defined as the average distance between the original tooth structure and the base of demineralization.
The pH was lower in UK apple juice, orange juice, Diet Pepsi® and Sprite Zero® (p<0.05), and higher in UK orange soda and diet orange soda than in similar US beverages (p<0.05). Titratable acidities were higher in UK apple juice, orange juice, orange soda, diet orange soda and Sprite® (p<0.01), and lower in UK Sunny D® than in the US counterpart (p<0.001). Fluoride concentrations were lower in UK apple juice, orange juice, Coke®, and Diet Coke®, Sprite® and Sprite Zero® (p<0.001), and higher in UK orange soda, diet orange soda, Pepsi® and Diet Pepsi® than in their US counterparts (p<0.001). Lesion depths were higher in UK apple juice, orange juice, Diet Coke®, Sprite® and Sprite Zero® than in their US counterparts (p<0.05). Lesion depths were associated with pH (p=0.010) and country of origin (p=0.002).
Under similar laboratory conditions, the physiochemical properties and erosion potentials on enamel surfaces differed between some, but not all, beverages available in the UK and the US.
Beverages; pH; titratable acidity; erosion; fluoride
The objective of this study was to compare the antimicrobial activity of commercially available antiseptic mouthrinses against saliva-derived plaque biofilms in static and flow-through biofilm systems in vitro.
Nine mouthrinses were tested in a recirculating flow-through biofilm model (RFTB) with viability assessment by ATP bioluminescence. In addition, five mouthrinses were evaluated in a batch chamber slide biofilm (BCSB) model, using live- dead staining and confocal laser scanning microscopy.
In the RFTB model, essential oil (EO) and chlorhexidine (CHX)-containing rinses showed equivalent antimicrobial activity and were more effective than a range of cetyl pyridinium chloride (CPC1) formulations. In the BCSB model, twice-daily mouthrinse exposure demonstrated that the EO rinse was significantly more effective than rinses containing amine and stannous fluorides, a combination of CPC/CHX and CPC2. EO showed biofilm kill comparable to the CHX rinse.
The present studies have shown that mouthrinses vary significantly in their capability to kill plaque biofilm bacteria in BCSB and RFTB models. The EO mouthrinse demonstrated superior antiplaque biofilm activity to AFSF, CPC/CHX, and CPC rinses and comparable activity to CHX. The methods tested may be of value for the in-vitro screening of antiseptic rinses with different modes of antimicrobial action.
biofilm; antiplaque; mouthrinse; antimicrobial; essential oils; chlorhexidine; cetylpyridinium chloride; amine fluoride; antiseptic; biocidal
To measure the denaturation temperature (Td) of demineralised dentine matrix as a function of infiltration with water vs polar solvents vs adhesive resins.
Small disks of normal dentine were completely demineralised in 0.5 M EDTA. Dried demineralised specimens were placed in water, methanol, ethanol, acetone, η-butanol or HEMA. Additional specimens were infiltrated with Prime & Bond NT and polymerised. All specimens sealed in high pressure pans and scanned using differential scanning calorimetry (DSC).
Demineralised dentine saturated with water showed a Td of 65.6°C that increased with saturation by methanol, ethanol, acetone, η-butanol or HEMA to 148.5°C. These increases in Td were inversely related to the molar concentration of the solvents and to their Hoy’s solubility parameter for hydrogen bonding (δh, p<0.01), as well as directly related to the cube root of their molecular weights (p<0.001). The presence of adhesive resins also increased the Td of demineralised matrices to even higher values depending if the resin bonded dentine was measured after 24 h of water storage (166.8°C) or dry (172.7°C) storage.
Solvents and monomers with low δh values (i.e. 100% HEMA) increase the Td of demineralized dentin above that produced by solvents with higher δh values such as methanol and water.
Collagen; Dentine; DSC; Glass transition temperature; Solvents; Resin
To quantify in vitro the root dentin moisture (DM) when soaked in 10% ascorbic acid solution (Group A) and distilled water (Group B) for up to 14 days.
Forty-four extracted human mandibular single-rooted teeth were sectioned perpendicular to the long axis at the CEJ to access the root dentin. The samples were divided into groups A and B. Baseline (day 0) DM was measured using a digital grain moisture meter. One sample was placed in each tube, which was then filled with solution. All tubes were kept at 37°C and 100% humidity. DM was measured after 1, 3, 7, and 14 days. The baseline DM value was used as a covariate in the generalized estimating equation (GEE) analysis to account for the difference in the baseline DM between the two groups.
The mean DM(%)values±standard deviation on days 0, 1, 3, 7, and 14 were 11.4±1.08, 17.1±0.87, 18.2±0.76, 18.4±0.77, and 17.9±0.90 in Group A, and 10.2±0.95, 12.8±0.90, 13.3±0.95, 13.0±0.91, and 13.2±0.89 in Group B, respectively. Group A had significantly higher baseline DM than Group B (p=0.006). After adjusting for differences in the baseline, the GEE analysis indicated that, on average, Group A had a significantly higher increase in DM than Group B, with means±standard deviation of 4.35±0.26.
The moisture increase in the ascorbic acid group was greater than that in the distilled water group. Soaking root dentin in the unreplenished ascorbic acid solution or distilled water beyond 3 days did not further increase DM.
Ascorbic acid; Bonding; Dentin moisture; Generalized estimating equation analysis; Rapid non-destructive method
To evaluate dentin tubule numerical density variations below the CEJ.
Three human non-carious permanent canines were sectioned parallel to the CEJ to obtain dentin disks 1 mm thick whose surfaces were 1 mm and 2 mm below the CEJ. Each disk was sectioned into quarters resulting in four segment locations: facial, lingual, mesial, and distal. The outer (PDL side) and inner (pulp side) surfaces of the specimens were shaped to expose dentin with SiC papers and polished. Numerical tubule density was determined from SEM images. All data were statistically analyzed using a three-way ANOVA.
The dentin tubule density (number/mm2) ranged from 13,700 to 32,300. Dentin tubule density was relatively uniform at 1 and 2 mm below the CEJ and increased by a factor of about two from the outer to the inner surface, which was significantly different (P<0.0001).
The tubule density variations at the cervical root did not present the marked changes.
Cemento-Enamel Junction (CEJ); Cervical lesions; Density; Dentin hypersensitivity; Dentin tubules; Root dentin; Scanning Electron Microscopy (SEM)
Grape seed extract (GSE) contains Proanthocyanidin (PA), which has been reported to strengthen collagen-based tissues by increasing collagen cross-links. We used an in vitro pH-cycling model to evaluate the effect of GSE on the remineralization of artificial root caries. Sound human teeth fragments obtained from the cervical portion of the root were stored in a demineralization solution for 96 hr at 37°C to induce artificial root caries lesions. The fragments were then divided into three treatment groups including: 6.5% GSE, 1,000 ppm fluoride (NaF), and a control (no treatment). The demineralized samples were pH-cycled through treatment solutions, acidic buffer and neutral buffer for 8 days at 6 cycles per day. The samples were subsequently evaluated using a microhardness tester; polarized light microscopy (PLM) and confocal laser scanning microscopy (CLSM). Data were analyzed using ANOVA and Fisher’s tests (p<0.05). GSE and fluoride significantly increased the microhardness of the lesions (p<0.05) when compared to a control group. PLM data revealed a significantly thicker mineral precipitation band on the surface layer of the GSE treated lesions when compared to the other groups (p>0.05), which was confirmed by CLSM. We concluded that grape seed extract positively affects the demineralization and/or remineralization processes of artificial root caries lesions, most likely through a different mechanism than that of Fluoride. Grape seed extract may be a promising natural agent for non-invasive root caries therapy.
To determine the perceptibility and acceptability of tooth color differences using computer-generated pairs of teeth with simulated gingival displayed on a calibrated color monitor using appropriate signal detection theory methodology (SDT).
Twelve dental professionals (four from each of the following groups: dentists, dental auxiliaries, and fixed prosthodontic technicians) and four dental patients served as subjects. Responses to tooth color differences (ΔE) were measured on each of the three principal axes of CIELAB color space (L*, a*, and b*). As a control, responses to ΔE = 0 (the false alarm rate) were also measured in the same experimental session.
No group differences among subjects were found. All gave 50% match or acceptance points that averaged about 1.0 ΔE units in the L* and a* directions, and 2.6 units in the b* direction. False alarm rates across all subjects averaged 27% (4–55%) and 28% (0.4–61%), respectively, for perceptibility and acceptability. A reanalysis of the data based on SDT, which takes subjects’ false alarm rates into account, gave somewhat larger color difference thresholds.
Color difference thresholds for our simulated teeth are generally in line with and extend results obtained with studies using “real” dental materials. No differences between thresholds for acceptability versus perceptibility were found.
Furthermore, subjects often reported color differences when none existed, and this behavior needs to be factored into any determination of quality control standards for the fabrication of dental prostheses.
Tooth color; Perceptibility; Acceptability; Signal detection; Color difference; Computer simulation
Compare occlusal contacts calculated from 3D virtual models created from clinical records to contacts identified clinically using shimstock and transillumination.
Upper and lower full arch alginate impressions and vinyl polysiloxane centric interocclusal records were made of 12 subjects. Stone casts made from the alginate impressions and the interocclusal records were optically scanned. Three-dimensional virtual models of the dental arches and interocclusal records were constructed using the Virtual Dental Patient Software©. Contacts calculated from the virtual interocclusal records and from the aligned upper and lower virtual arch models were compared to those identified clinically using 0.01 shimstock and transillumination of the interocclusal record. Virtual contacts and transillumination contacts were compared by anatomical region and by contacting tooth pairs to shimstock contacts. Because there is no accepted standard for identifying occlusal contacts, methods were compared in pairs with one labeled “standard” and the second labeled “test”. Accuracy was defined as the number of contacts and non-contacts of the “test” that were in agreement with the “standard” divided by the total number of contacts and non-contacts of the “standard”.
Accuracy of occlusal contacts calculated from virtual interocclusal records and aligned virtual casts compared to transillumination were: 0.87±0.05 and 0.84±0.06 by region and 0.95±0.07 and 0.95±0.05 by tooth, respectively. Comparisons with shimstock were: 0.85±0.15 (Record), 0.84±0.14 (Casts), and 81 ± 17 (Transillumination).
The virtual record, aligned virtual arches, and transillumination methods of identifying contacts are equivalent, and show better agreement with each other than with the shimstock method.
Occlusal Contacts; 3D scanning; Interocclusal Record; Transillumination