Hans Malmstrom

Effects of tooth whitening and orange juice on surface properties of dental enamel

OBJECTIVE To study the effects of 6% H2O2 activated with LED light on surface enamel as compared to orange juice challenges in vitro. METHODS A total of 40 human enamel discs were incubated in saliva overnight to allow pellicle formation and then divided into three groups: 15 for whitening treatments, 15 for orange juice immersions and 10 for normal saline controls. Baseline microhardness was measured with a microhardness Knoop indenter (50g, 10s) and surface topography was evaluated with a focus-variation 3D scanning microscopy. Enamel discs were treated with H2O2 or orange juice for 20 min each cycle for five cycles to simulate daily treatment with the products for 5 days. The discs were stored in saliva between treatment cycles. Microhardness and surface topography were evaluated again after treatments. Changes in microhardness and in surface area roughness (Sa), mean maximum peak-to-valley distance (Sz) and the developed surface area ratio (Sdr) were compared before and after treatments (t-test) and among groups (ANOVA). RESULTS Enamel surface hardness decreased by 84% after orange juice immersion but no statistically significant changes were observed in the whitening and control groups. Surface topography changed significantly only in the orange juice group as shown by increased Sa (1.2 microm vs. 2.0 microm), Sz (7.7 microm vs. 10.2 microm) and Sdr (2.8% vs. 6.0%). No such changes were observed in the whitening and control groups. CONCLUSION In comparison to orange juice challenges, the effects of 6% H2O2 on surface enamel are insignificant. Orange juice erosion markedly decreased hardness and increased roughness of enamel.

Effects of common beverage colorants on color stability of dental composite resins: The utility of a thermocycling stain challenge model in vitro

OBJECTIVES To study the color stability of dental composite resins using a thermocycling stain challenge model accounting for the complex effects of oral environment and tooth brushing. METHODS Composite resin discs were made from Filtek Supreme Ultra (FiltekSU), TPH3 and Renamel, and subjected to thermocycling challenges in warm coffee (55 °C/pH 5.2) and a cold tea and fruit juice mixtures (5 °C/pH 3.6) for a total of 1000 cycles with 30 seconds dwell time in each solution per cycle. Color was assessed in the CIELAB color space using a Crystaleye dental spectrophotometer before and after thermocycling, and after brushing vigorously for 3 min. The thermocycling stain challenge was repeated for a second 1000 cycles and the discs were brushed again. Color changes were compared among the 3 groups using Kruskal-Wallis test. RESULTS All 3 groups showed statistically significant color changes after stain challenge, with ΔE* as 5.74 for FiltekSU, 3.21 for TPH3 and 2.52 for Renamel. Color change was more significant in FiltekSU than in TPH3 and Renamel (p<0.05). After brushing, color recovered mostly to its original CIELAB values in TPH3 and Renamel but less so in FiltekSU. The second round of thermocycling stain challenge resulted in color changes in FiltekSU that largely could not be removed by vigorous brushing. CONCLUSIONS Color stability of FiltekSU is inferior to that of TPH3 and Renamel. The thermocycling stain challenge model can potentially differentiate surface staining that can be removed by brushing from true discoloration of the material that is refractory to oral hygiene procedures.

Effect of CO2 laser on pulpal temperature and surface morphology: an in vitro study

OBJECTIVES The objective of this study was to evaluate the potential effects on underlying dental hard tissues of a high pulse rate carbon dioxide (CO2) laser that was designed for soft tissue surgery. METHODS Eighteen extracted human teeth were sectioned longitudinally, cleaned, and varnished, leaving nine exposed windows on each: six on the coronal surface (enamel) and three on the root surface (cementum, dentin). The CO2 irradiation conditions used were: wave length 10.6 microm; 1.2-2.6J/cm(2) fluence per pulse; repetition rate 120-1000Hz; 100-200ms pulse duration; and cumulative fluences ranging from 14 to 2200J/cm(2). Each window was irradiated with a 0.3mm beam diameter at one of nine power settings for 0.1, 0.5, or 1.0s. The pulp chamber temperature was measured with a microthermocouple. The irradiated teeth were evaluated by Polarized Light Microscopy (PLM) and Scanning Electron Microscopy (SEM). RESULTS The pulp chamber temperature rise ranged from 0.5 to 19 degrees C depending on the location of the window and distance to pulp chamber. SEM revealed crystal fusion in both enamel and dentin at all cumulative fluences. At cumulative fluences of 40J/cm(2), 200 pulses/second and higher, measurable tissue loss was observed with PLM both in dentin and enamel. CONCLUSIONS These results indicate there are threshold conditions above which pulsed CO2 laser light used for soft tissue surgery may cause detrimental changes to underlying oral hard tissue and to the pulp.

Assessing fluoride treatment and resistance of dental enamel to soft drink erosion in vitro: Applications of focus variation 3D scanning microscopy and stylus profilometry

OBJECTIVES This study assesses the application of the focus variation 3D microscopy for the evaluation of dental erosion and fluoride treatment for prevention of enamel erosion in vitro. METHODS Human dental enamel disks were treated with Prevident 5000 (PV, n=15) for 1 week and compared with a reference group (PN, n=15) after orange juice erosion in vitro. A focus variation 3D scanning microscope (IFM) and a stylus type profilometer (SSP) were used to evaluate the erosion depths on enamel. 3D topographic images were taken with vertical resolutions of 0.1 and 0.02 microm. Scratch marks depths from SSP were measured on IFM images. Measurements were compared between the SSP and IFM and between the two study groups. RESULTS The SSP and IFM measurements of eroded enamel surfaces showed similar trends between the two methods and between the two study groups. The SSP and the IFM measurements were statistically significantly different but correlated with each other. PV group showed consistently lower erosion depth than PN in all profile measures using both SSP and IFM. The stylus tip created scratch marks that were significantly different in depths between the eroded and the reference surfaces in both groups. CONCLUSIONS The focus variation 3D microscopy is a powerful tool in evaluating surface topography associated with enamel erosion and in assessing the treatment effects of anti-erosive therapies. Topical treatment with Prevident 5000 significantly increased enamel resistance to erosion by orange juice and should be considered as a treatment choice in patients susceptible to acidic dental erosion.

Comparison of Clinical and Radiographic Periodontal Status Between Habitual Water-Pipe Smokers and Cigarette Smokers.

BACKGROUND There is a dearth of studies that have compared clinical and radiologic markers of periodontal inflammation between water-pipe smokers (WPs) and cigarette smokers (CSs). The aim of the present study is to compare the clinical and radiographic periodontal status between habitual WPs and CSs. METHODS In total, 200 males (50 WPs, 50 CSs, and 100 controls) with comparable mean age and education were included. Demographic information was recorded using a questionnaire. Periodontal parameters (plaque index [PI], bleeding on probing [BOP], probing depth [PD], clinical attachment loss [AL], and marginal bone loss [MBL]) and numbers of missing teeth (MT) were recorded. RESULTS The duration of each smoking session for WPs and CSs was 50.2 ± 6.7 and 15.3 ± 0.4 minutes, respectively. Number of MT [P <0.0001], PI [P <0.0001], AL [P <0.0001], PD ≥4 mm [P <0.0001], and MBL [P <0.0001]) was significantly higher among WPs and CSs than controls. BOP was significantly higher among controls than WPs (P <0.0001) and CSs (P <0.0001). There was no statistically significant difference in the aforementioned parameters between WPs and CSs. CONCLUSIONS Males in a Saudi Arabian community who were CSs or WPs had more MT and poorer periodontal condition than never smokers. The periodontal condition of WPs was equally as poor as CSs. Additional clinical observational studies with emphasis on sex and sociodemographic characteristics are needed.

Preventive effects of dentifrice containing 5000 ppm fluoride against dental erosion in situ

OBJECTIVE To evaluate the effectiveness of a dentifrice with 5000ppm fluoride in preventing dental erosion by orange juice in situ in comparison to a control dentifrice with 1450ppm fluoride. METHODS This was a double-blind and randomized clinical study with a cross-over design. Sixteen subjects wore an intra-oral appliance containing two enamel disks with an exposed surface of approximately 2mm×5mm. Enamel disks in the study group were treated with a dentifrice with 5000ppm fluoride and in the control group with 1450ppm fluoride. The subjects rinsed with slurries of study dentifrices for one minute before immersing the enamel disks in 250ml orange Juice four times in an 8-h period daily. The treatment procedure was repeated for three 5-day phases for each dentifrice. Enamel erosion was measured after each 5-day treatment phase using a focus-variation 3D scanning microscopy. Medians and inter-quartile ranges (IQR) of mean erosion depth were compared between the groups. RESULTS The mean erosion depths of enamel varied greatly amongst the subjects. Enamel treated with 5000ppm fluoride had less erosion (median 5.7μm, IQR 4.5μm) as compared to the control (median 12.6μm, IQR 12.3μm) after 15 days of fluoride treatment and erosive challenge cycles (p<0.05). CONCLUSIONS Enamel treated with 5000ppm fluoride had significantly improved resistance to erosion by orange juice. Periodic application of 5000ppm fluoride may be beneficial in individuals at risk of acidic erosion associated with soft drink consumptions.

In Vitro Assessment of Primary Stability of Straumann® Implant Designs

BACKGROUND Primary implant stability (PS) is one of the main factors influencing implant survival rate. Several methods to determine the PS have been used, such as Periotest values (PVs) and resonance frequency analysis (RFA) with implant stability quotient (ISQ) values. PURPOSE The aim of this study was to compare different implant designs in regard to PS assessed by Periotest and RFA in vitro. MATERIALS AND METHODS A total of 90 implants were placed in freshly slaughtered cow ribs. The implants (Straumann®, Institute Straumann AG, Basel, Switzerland; length 10 mm, ø3.3 mm) had the following three designs: Bone Level (BL, 30 implants), Standard Plus (SP, 30 implants), and Tapered Effect (TE, 30 implants). Before implant placement, the investigator was calibrated for every design according to the manufacturers instructions. An independent observer, blinded to the study, assessed the accuracy of placement. RFA based on the Osstell device and PVs were performed after abutment connection. One-way analysis of variance and Tukeys post hoc test were used for statistical evaluation. RESULTS All implants were mechanically stable. The mean PV for BL was -4.67(± 1.18), for SP, -6.07(± 0.94), and for TE, -6.57(± 0.57). The mean ISQ values were 75.02(± 3.65), 75.98(± 3.00), and 79.83(± 1.85), respectively. The one-way ANOVA showed significant difference among three implant designs in PV (p < .0001) and for the ISQ between BL/TE or SP/TE implants (p < .0001). In addition, the Tukeys (pair-wise comparison) test showed significant differences in PV and RFA between the BL/T (p < .0001). CONCLUSION Within the limitations of this study, higher implant stability was found for tapered designed implants.

Periodontal Status and Whole Salivary Cytokine Profile Among Smokers and Never-Smokers With and Without Prediabetes

BACKGROUND Whole salivary interleukin (IL)-1β and IL-6 in smokers and never-smokers with prediabetes remains uninvestigated. The aim of this study is to assess the periodontal status and whole salivary IL-1β and IL-6 levels among smokers and never-smokers with and without prediabetes (controls). METHODS Ninety-five males (45 with prediabetes and 50 systemically healthy controls) were included. Twenty-seven controls and 29 patients with prediabetes were smokers. Periodontal parameters (plaque index, bleeding on probing, probing depth, clinical attachment loss, and marginal bone loss) were measured, and the number of missing teeth were recorded. Fasting blood glucose (FBG) and hemoglobin A1c (HbA1c) levels were recorded. Unstimulated whole saliva samples were collected, unstimulated whole salivary flow rate (UWSFR) was determined, and IL-1β and IL-6 levels were measured. P values <0.05 were considered statistically significant. RESULTS FBG (P <0.05) and HbA1c (P <0.05) levels were higher among patients with prediabetes than controls. All patients with prediabetes were hyperglycemic. UWSFR was significantly higher among controls than among patients with prediabetes (P <0.05). Periodontal parameters and whole salivary IL-1β and IL-6 levels were comparable among smokers and never-smokers with prediabetes. Among controls, periodontal parameters and whole salivary IL-1β and IL-6 levels were higher among smokers than never-smokers (P <0.05). CONCLUSIONS Among controls, periodontal inflammation was worse, and whole salivary IL-1β and IL-6 levels are higher in smokers than never-smokers. Among patients with prediabetes, periodontal inflammation and whole salivary IL-1β and IL-6 levels were comparable between smokers and never-smokers.

Expression of Ecto-ATPase NTPDase2 in Human Dental Pulp

Dental pulpal nerve fibers express ionotropic adenosine triphosphate (ATP) receptors, suggesting that ATP signaling participates in the process of dental nociception. In this study, we investigated if the principal enzymes responsible for extracellular ATP hydrolysis, namely, nucleoside triphosphate diphosphohydrolases (NTPDases), are present in human dental pulp. Immunohistochemical and immunofluorescence experiments showed that NTPDase2 was predominantly expressed in pulpal nerve bundles, Raschkow’s nerve plexus, and in the odontoblast layer. NTPDase2 was expressed in pulpal Schwann cells, with processes accompanying the nerve fibers and projecting into the odontoblast layer. Odontoblasts expressed the gap junction protein, connexin43, which can form transmembrane hemichannels for ATP release. NTPDase2 was localized close to connexin43 within the odontoblast layer. These findings provide evidence for the existence of an apparatus for ATP release and degradation in human dental pulp, consistent with the involvement of ATP signaling in the process of dentin sensitivity and dental pain.

Periodontal Inflammatory Conditions Among Smokers and Never-Smokers With and Without Type 2 Diabetes Mellitus

BACKGROUND There is a dearth of studies regarding the influence of cigarette smoking on periodontal inflammatory conditions among patients with type 2 diabetes mellitus (T2DM). The aim of the present study is to assess periodontal inflammatory conditions among smokers and never-smokers with and without T2DM. METHODS One hundred individuals (50 patients with T2DM [25 smokers and 25 never-smokers] and 50 controls [25 smokers and 25 never-smokers]) were included. Information regarding age, sex, duration and daily frequency of smoking, duration and treatment of diabetes, and oral hygiene was recorded using a questionnaire. Periodontal parameters (plaque index [PI], bleeding on probing [BOP], probing depth [PD], clinical attachment loss [AL], and marginal bone loss [MBL]) were measured. Hemoglobin A1c (HbA1c) levels were also recorded. RESULTS Mean age, monthly income status, and education levels were comparable among smokers and never-smokers with and without T2DM. Mean HbA1c levels were significantly higher among patients with T2DM (8.2% ± 0.1%) compared with controls (4.4% ± 0.3%) (P <0.05). Smokers in the control group were smoking significantly greater numbers of cigarettes (15.5 ± 2.5 cigarettes daily) compared with smokers with T2DM (6.2 ± 2.1 cigarettes daily) (P <0.05). Periodontal parameters were comparable among smokers and never-smokers with T2DM. Among controls, periodontal parameters (PI [P <0.05], AL [P <0.05], PD ≥4 mm [P <0.05], and MBL [P <0.05]) were significantly higher in smokers than never-smokers. Never-smokers with T2DM had worse periodontal status than smokers and never-smokers in the control group (P <0.05). CONCLUSIONS Periodontal inflammatory conditions are comparable among smokers and never-smokers with T2DM. Among controls, periodontal inflammation is worse among smokers than never-smokers.