The development of a tool to predict temperature-exposure of incinerated teeth using colourimetric and hydroxyapatite crystal size data.

This study presents a novel tool to predict temperature-exposure of incinerated pig teeth as a proxy for understanding impacts of fire on human teeth. Previous studies on the estimation of temperature-exposure of skeletal elements have been limited to that of heat-exposed bone. This predictive tool was developed using a multinomial regression model of colourimetric and hydroxyapatite crystal size variables using data obtained from unheated pig teeth and teeth incinerated at 300 °C, 600 °C, 800 °C and 1000 °C. An additional variable based on the observed appearance of the tooth was included in the tool. This enables the tooth to be classified as definitely burnt (600 °C-1000 °C) or uncertain (27 °C/300 °C). As a result, the model predicting the temperature-exposure of the incinerated teeth had an accuracy of 95%. This tool is a holistic, robust and reliable approach to estimate temperature of heat-exposed pig teeth, with high accuracy, and may act as a valuable proxy to estimate heat exposure for human teeth in forensic casework.

Successful minimally invasive management of primary maxillary central incisors after lateral luxation: a case report.

Lateral luxation in primary maxillary incisors is a traumatic injury that can lead to darkening of the tooth, pulp necrosis, root resorption, and damage to the permanent teeth. Management of this kind of trauma typically includes pulpectomy or extraction in cases of root resorption. However, in young children, removal of the tooth may be psychological stressing, especially for the parents, while increased mobility can make immediate endodontic treatment difficult to perform. This article outlines a severe palatal luxation on the maxillary right central incisor treated with conservative management in a 2-year-old boy. At the one-year follow-up appointment, the surrounding bone was healthy, the roots displayed physiological resorption, the crowns showed color improvement, and there was no radiographically noticeable damage to the permanent teeth.

Comparative fluorescence spectroscopy of root caries lesions.

In this study, the light-emission properties of carious and sound root surfaces were investigated under a wide range of excitation wavelengths. Human molar teeth with exposed root surfaces containing light- and dark-discolored root caries (n = 3 of each) were selected. Emission spectra were recorded from carious and corresponding sound root surface areas from each tooth by using a fluorescence spectrophotometer at excitation wavelengths from 360 nm up to 580 nm, in steps of 20 nm. The spectra were corrected for fluctuations in detector sensitivity and excitation light intensity, and normalized to peak intensity. Excitation spectra were recorded for selected emission wavelengths that showed maximum intensity. Light- and dark-discolored root surface caries showed distinct fluorescence emission bands between 600 and 700 nm that were not present in sound root surface areas. These bands were strongest for excitation wavelengths between 390 and 420 nm. The excitation spectra of root caries revealed maximum excitation at around 405 nm, which is equivalent to the Soret band of porphyrin compounds. The emission spectra of both types of root caries lesions were shifted towards longer wavelengths (red shift at half maximum) when compared to the spectra of corresponding sound root surfaces. The red shift for dark-discolored root caries was higher than for light-discolored lesions at all excitation wavelengths.

Laser Doppler flowmetry of luxated permanent incisors: a receiver operator characteristic analysis.

Laser Doppler flowmetry (LDF) is a non-invasive method to assess pulpal blood-flow (PBF). Dental luxation injuries have been associated with significant PBF reduction. The purpose of this study was to describe diagnostic characteristics for different session-related threshold PBF values for detection of specific adverse outcomes. In 61 trauma patients, a single maxillary incisor treated by repositioning and splinting, and the respective contralateral homologous control tooth were investigated by LDF to assess local PBF values. Perfusion units (PU) were taken 12 weeks (session I) and 24 weeks (session II) after splint removal. The ability of session I-related PBF measurements at 2.8, 6.4 and 10.1 PU levels, and of session II-related ameasurements at 2.4, 6.3 and 10.2 PU levels to identify adverse outcomes occurring 36 weeks after splint removal was investigated. Adverse outcomes were classified as type I (periapical radiolucency), type II (grey discoloration), and type III (periapical radiolucency and grey discoloration of crown). Receiver operator characteristic curves were used to evaluate the sensitivity and specificity of PBF assessments. There was no significant difference in PBF values between session I and session II (P > 0.05) for teeth without an adverse outcome, and those with a type I, II or III outcome (P > 0.05). The PBF measurements did not change over time for the contralateral incisors (P > 0.05). A type I, II and III outcome occurred in 36, 21 and 12% of the incisors, respectively. The best likelihood ratio was found for the PBF 6.4 PU level at session I and incisors associated with a type I (20.8) and type II outcome (15.2). The PBV of 6.4 PU demonstrated a sensitivity of 96% and a specificity of 59% for type I outcomes, and a sensitivity of 100% and a specificity of 50% for type II outcomes. The data suggest the LDF test to be a valuable diagnostic adjunct for luxated teeth showing signs of adverse outcomes.

Evaluation of pulpal blood flow after tooth splinting of luxated permanent maxillary incisors.

Laser Doppler flowmetry (LDF) is a non-invasive method to assess pulpal blood flow (PBF). Dental injury has been associated with losses of pulpal sensibility. The purpose of this study was to assess whether LDF could be used to detect short- and long-term changes of PBF values of luxated permanent maxillary central incisors after repositioning and splinting. In 18 trauma patients, a single maxillary incisor treated by repositioning and splinting, and the respective contralateral homologous tooth were investigated by LDF to assess local PBF values. Perfusion units (PU) were taken in four sessions: on the day of splint removal, and 12, 24, and 36 weeks after splint removal. Analysis of the luxation type-related PBF measurements revealed intrusion type-related PBF values to be associated with a significant decrease in PBF values (P < 0.05), while lateral luxation and extrusion type-related PBF values showed no significant difference between the session-related values (P > 0.05). PBF measurements did not change over time for the contralateral incisors (P > 0.05). Teeth affected by an intrusion-type luxation injury remained unresponsive to sensitivity testing at follow up, while 3 (60%) developed grey discoloration of the crown. LDF may become useful in the detection of ischemic episodes of luxated maxillary central incisors after repositioning and splinting. Further studies are warranted to assess the validity of post-traumatic 'ischemic episodes' by comparing it to histological tooth pulp changes.

Threshold contrast ratio and masking ability of porcelain veneers with high-density alumina cores.

PURPOSE: The purposes of this study were to: (1) investigate the correlation between the color difference of bilayer porcelain veneers over white and black backgrounds (deltaE1) and their opacity (contrast ratios); (2) determine whether there is a recommendable threshold contrast ratio above which the color difference is clinically acceptable (when deltaE < or = 5); and (3) compare the ability of porcelain veneers to mask a color change from white to black backgrounds (deltaE1) and their ability to mask a color change from white to clinically discolored teeth (deltaE2). MATERIALS AND METHODS: Forty-four maxillary anterior teeth of eight patients with severe tetracycline discoloration were prepared for bilayer porcelain veneers in shade A2 porcelain. The cores were 0.25 mm thick. The color (CIE L*a*b*) and reflectance (Y) of the midbuccal region of each veneer were measured over white and black backgrounds using a colorimeter under artificial daylight. The veneers were bonded to discolored teeth, and their color was measured after 1 week. RESULTS: The mean color difference deltaE1 was 10.6 (SD 2.6). The mean contrast ratio was 0.75 (SD 0.1). There was a close and statistically significant correlation between deltaE1 and contrast ratio. The determined threshold contrast ratio was 0.91. The mean color difference deltaE2 was 11.6 (SD 5.5). A paired t test showed no difference between deltaE1 and deltaE2. CONCLUSION: There was a significant correlation between the masking ability of veneers (deltaE1) and their opacity (contrast ratio). There was no significant difference in the ability of the porcelain veneers in masking a color change from white to black backgrounds compared to their ability to mask the color change from white to the discolored teeth.

Nanomechanical properties of hydrated carious human dentin.

Most restorative materials are bonded to caries-affected dentin that has altered structure. We tested the hypothesis that hydrated dentin of the transparent zone did not have increased hardness or elastic modulus. Nanoindentation by modified AFM was used to determine site-specific elastic modulus and hardness for components of hydrated dentin from 8 carious and non-carious human teeth. Indentations in intertubular dentin were made at intervals from pulp through the affected layers (subtransparent, transparent, and discolored zones). The values of intertubular dentin increased slightly from near the pulp into the transparent zone, then remained constant or decreased slightly through transparent dentin (E, 18.3 GPa; H, 0.8 GPa; confirming the hypothesis), and decreased markedly through the discolored region. Peritubular dentin values were unaltered in transparent dentin, and intratubular mineral had values between those of normal peritubular and intertubular dentin. Superficial areas contained distorted tubules without peritubular dentin or intratubular mineral.

Influence of window size in small-window colour measurement, particularly of teeth.

Tooth colour is often measured with a small window for illumination and measurement. This causes edge loss of the light, resulting in systematic errors in colour coordinates. This paper gives a quantification of the edge losses, and explains their cause. We measured reflectance spectra for 27 Formalin fixated extracted incisors using a small-window reflectance spectrophotometer equipped with external diaphragms of 3, 4, and 5 mm diameter, and using a spectroradiometer. We calculated the colour coordinates L*a*b* from these spectra. Finally, 16 randomly chosen teeth were illuminated with a pencil beam (lambda = 543 nm, and lambda = 633 nm) while the emerging light was measured as a function of distance from the illuminated spot using a CCD detector. These data were used to calculate small-window edge losses, and thus to predict the small-window reflectance factors relative to spectroradiometrically determined reflectance, at both 543 nm and 633 nm. In all instruments the same spot on the tooth was illuminated and measured, and the teeth were always wet. Colour coordinates for the small-window colour measurements deviate significantly from those determined using the spectroradiometer. These deviations can be explained from the wavelength-dependant edge loss that arises in small-window colour measurement.

Comparison of 2 chlorhexidine mouthwashes on plaque regrowth in vivo and dietary staining in vitro.

Until recently, the few available chlorhexidine mouthrinse products have been 0.2% formulations. However, concentrations of 0.12% chlorhexidine appear as effective as 0.2%, if the volume of the rinse is increased to 15 ml. Since the mere incorporation of chlorhexidine in a formulation does not guarantee availability of the antiseptic, it would seem reasonable to evaluate or compare all products. This is particularly the case when other ingredients, such as fluoride are added. The 1st study compared the effect of a 0.12% chlorhexidine rinse with a 0.12% chlorhexidine/0.022% sodium fluoride rinse for effects on plaque regrowth. The study was a 7-day, blind, randomised, 2-cell cross-over design with a baseline control run in period, in which 18 subjects participated. Both chlorhexidine products significantly reduced plaque compared to control but the chlorhexidine fluoride rinse was less effective than the chlorhexidine only rinse. The 2nd study assessed the propensity of the chlorhexidine rinses to induce dietary staining in vitro. For the chlorhexidine fluoride rinse, this was less than the other 0.12% rinse and a commonly used 0.2% product. The data in vivo and in vitro suggest reduced chlorhexidine availability from the chlorhexidine fluoride product which appears to cause some loss of efficacy.

Oral complications of acute leukemia: prophylactic impact of a chlorhexidine mouth rinse regimen.

The prophylactic value of twice-daily mouth rinses with a solution of 0.1% chlorhexidine gluconate in minimizing oral complications during remission-induction chemotherapy was tested in sixteen patients with acute myeloblastic leukemia. The study design was double blind with a placebo control. Standardized measurement indices were employed to assess the dental plaque levels and the degree of gingivitis and mucositis during remission-induction. The treatment group demonstrated superior oral health on the basis of each of these measurement parameters. A moderate increase in tooth staining was observed in the treatment group. The results also suggested the potential value of chlorhexidine mouth rinses in the prophylaxis of oral candidiasis in the myelosuppressed patient.

Effects of nicotine-containing chewing gum on oral soft and hard tissues: A clinical study.

A double-blind clinical trial was conducted to determine whether the use of a chewing gum containing 2.0 mg nicotine (as an adjunct to a stop-smoking program) had any effects upon oral health. A total of 193 adults who smoked cigarettes volunteered with informed consent, were given routine dental prophylaxes, and were examined for the presence of plaque, stained pellicle, gingivitis, calculus, and general oral pathosis. The subjects were then randomly assigned to use either a nicotine-containing or a placebo chewing gum. After 15 weeks the subjects were recalled and re-examined. Smoking cessation was determined through questionnaire and analysis of the carbon monoxide content of alveolar air. At the completion of the study, 79 subjects had used the placebo gum and 78 had used the nicotine gum. Data analysis indicated that the nicotine chewing gum had no significant influence on any of the oral health parameters graded, as compared to the placebo gum. The continuation of smoking, however, was associated with significant increases in gingivitis and calculus rates.

Effects of sequential calcium phosphate-fluoride rinses on dental plaque, staining, fluoride uptake, and caries in rats.

Oral rinses which included (1) an acidic calcium phosphate solution containing 0.7 M Ca, 1.9 M PO4, and saturated with respect to CaHPO4 . 2H2O, and with a pH of 2.0, followed by (2) a 0.52 M fluoride solution, from NaF or SnF2, were provided to rats once daily for seven days. The investigation consisted of two studies: In the first study, the amounts of dental plaque on the tooth surfaces and fluoride concentrations in the outer enamel were assessed seven days after the last treatment; in the second study, the extent of dental caries was evaluated seven weeks after the last treatment. All rinse sequences containing fluoride provided significant caries protection. The acidic calcium phosphate treatment markedly enhanced the ability of the enamel to acquire fluoride without change of surface morphology. Only the rinse sequences that included stannous fluoride showed significant plaque suppression.

The effect of surface adsorption and staining reactions on the antimicrobial properties of some cationic antiseptic mouthwashes.

The phenomenon of surface adsorption appears fundamental to the antiplaque activity of the cationic antiseptics. Moreover, reaction with chromogenic material is relevant to the local side effect of staining. The purpose of this investigation was to determine how such local reactions affect the antibacterial activity of some of these antiseptics. The minimum inhibitory concentration (MIC) of commercial mouthrinses containing alexidine, cetyl pyridinium chloride, chlorhexidine gluconate and hexetidine against Oxford staphylococcus (NCTC 6571) and Escherichia coli (NCTC 10418) was established by tube dilution. The effect on the MIC values against O. staphylococcus of adding polymethylmethacrylate polymer or against E coli of adding a standard tea solution was then measured. The zones of inhibition around acrylic blocks soaked in the respective antiseptics, with and without postexposure washings, were measured. The effects on zone width of placing the antiseptic-soaked blocks in tea were recorded. The MIC values of alexidine, cetyl pyridinium chloride and chlorhexidine gluconate, but not hexetidine, were all increased by adding polymethylmethacrylate to cultures. Tea added to the culture increased the MIC values against E. coli for alexidine, chlorhexidine and hexetidine, but not for cetyl pyridinium chloride. Zones of inhibition around antiseptic-treated blocks were reduced by washing and, in the case of hexetidine, completely abolished. Tea-soaking further reduced the zones of inhibition for alexidine and chlorhexidine, but not cetyl pyridinium chloride.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of chlorhexidine and four antimicrobial compounds on plaque, gingivitis, and staining in beagle dogs.

Solutions containing 0.2% of a bis-biguanide, chlorhexidine (positive control), and four bis-amidinourea antimicrobial agents were tested in beagle dogs in a 12-week study. The five agents significantly reduced clinical plaque and gingivitis scores, and gingival fluid volumes in treated dogs, compared with water. All compounds reduced the stain area scores compared to water controls. Stain intensity scores were higher for chlorhexidine than for the four new antimicrobial agents and the water controls. There were no overt behavioral changes. Histological examination of oral tissues revealed no irritation.