Food impaction on three-dimensional printed models with periodontal ligament simulation.

OBJECTIVE: This study aims to evaluate food impaction on three-dimensional (3D) printed models with periodontal ligament simulation. MATERIALS AND METHODS: Based on a commercial typodont pair, 3D maxillary and mandibular models were created with no teeth and with tooth sockets that were 1 mm wider than the original ones from 24 to 27 or 34 to 37 for periodontal ligament simulation with vinyl polysiloxane impression material. In total, 35 pairs of 7 combinations, including maxillary/mandibular typodonts in occlusion with maxillary/mandibular 3D models with/without a distal gap of canines on 3D models (tooth 23 or 33) were mounted on hinge articulators and divided into seven groups (n = 5). Each sample experienced the same manual chewing simulation on a customized device. The proximal surfaces were photographed to measure the percentage of food impaction area using ImageJ software. RESULTS: Group with fixed maxillary and mandibular teeth showed more food impaction than other groups with significant differences in the average of maxilla and the average of all proximal areas. CONCLUSION: The flexibility of the periodontal ligament and the degree of freedom of the teeth in their sockets may contribute to the extent of food impaction in proximal spaces.

Coffee-stained tooth enamel color restoration and surface abrasion with whitening and regular toothpaste.

PURPOSE: To evaluate the effectiveness of whitening toothpaste in restoring tooth color after coffee staining and its potential impact on enamel surfaces compared with regular toothpaste. METHODS: Bovine tooth enamel specimens were prepared and stained with coffee solutions before undergoing brushing simulation with different toothpaste slurries (whitening, regular, reference). For precise evaluation, spectrophotometric measurements were taken at intervals to assess color changes using the CIELAB (Commission Internationale de l'Éclairage Lab*) color space. Additionally, profilometric measurements were taken to determine the impact of toothpaste type on the roughness and abraded depth of the enamel surface. To understand the effects of toothpaste and brushing on color change, surface roughness, and abraded depth, while also considering correlations between these factors, the findings were analyzed using mixed-effects models. RESULTS: The whitening toothpaste group demonstrated the highest recovery rate (71%) after 10,000 brushstrokes, followed by the regular toothpaste group (48%) and the reference slurry group (43%). The mixed-effects model analysis revealed that the reference group had a smaller change in lightness (ΔL) than those in the regular toothpaste group. The whitening toothpaste group showed a greater change in lightness on average than those in the regular toothpaste group, with an increase in lightness as the number of brushstrokes increased. According to the roughness and abraded depth data, the whitening toothpaste group was least affected by brushing, while the reference and regular toothpaste groups showed higher levels of roughness and abraded depth at all intervals. CLINICAL SIGNIFICANCE: Gaining a thorough understanding of the effectiveness of whitening toothpaste and its impact on the enamel surface plays a crucial role in refining toothpaste formulations and advancing tooth whitening techniques in dental care.

Examining enamel-surface demineralization upon exposure to acidic solutions and the remineralization potential of milk and artificial saliva.

The enamel surface may undergo demineralization due to exposure to acidic substances and the remineralization of the etched enamel is crucial to regain or maintain integrity. This study aimed to investigate the erosive effect of 10 acidic solutions on tooth enamel and the remineralization capacity of milk and artificial saliva by measuring surface roughness (Ra), enamel depth, and microhardness. A total of 80 bovine incisor enamel specimens were immersed in 10 different acidic solutions, including four different acidic drinks, three different citric acid solutions, and three different citric acid buffer solutions, for 1 h. After demineralization, the specimens were immersed in milk and artificial saliva for 3 h. Surface roughness, enamel abraded depth, and microhardness were measured before demineralization, in-between time intervals and after remineralization. Data were analyzed using Friedman and Kruskal-Wallis tests (p < 0.05). The results indicate a significant difference in surface roughness between the measurements taken at different time intervals, particularly between the baseline and after 1 h demineralization. Also, the specimens immersed in CAB1 exhibited greatest increase in Ra among other acidic solutions (Δ: 0.18 ± 0.07). Moreover, only the microhardness increased after remineralization (p < 0.05). Enamel demineralization using various acidic solutions revealed increased Ra and enamel abraded depth, and decreased microhardness. The use of remineralization agents, milk and artificial saliva, demonstrated an increase in microhardness. This study provides insights into the effects of different acidic solutions and potential remineralization agents on tooth enamel.

Investigating the role of chlorogenic acids and coffee type in coffee-induced teeth discoloration.

OBJECTIVE: Coffee is one of the most popular beverages in the world, with millions of people consuming it every day. The effect of coffee on teeth discoloration has long been a concern for both coffee drinkers and dental professionals. To address this concern, this study aimed to investigate the role of chlorogenic acids (CGAs) and the type of coffee in coffee-induced teeth discoloration. MATERIALS AND METHODS: High-performance liquid chromatography with a photodiode array detector was used to determine the CGA contents of instant coffee produced by five manufacturers (Starbucks, Dunkin' Donuts, Kanu, Ediya, Coffee Bean). A total of 180 bovine tooth specimens were immersed in the coffee samples for varying durations (3, 9, 24, 48, and 72 h), and the discoloration levels were measured using a spectrophotometer. A linear mixed-effects model analysis was used to determine the significance of L*, a*, and b* values in relation to the duration of coffee immersion and coffee type. RESULTS: Both immersion time and coffee type had significant effects on tooth discoloration (p < 0.001), with some types of coffee being more strongly associated with tooth discoloration than others. The amount of CGAs present in coffee was found to be positively correlated with the degree of discoloration (p = 0.030). CONCLUSIONS: Prolonged exposure to coffee can exacerbate teeth staining, and different types of coffee can cause varying degrees of discoloration. Furthermore, coffee with higher levels of CGAs may lead to greater tooth discoloration.

Shear bond strength of orthodontic brackets bonded with primer-incorporated orthodontic adhesives and unpolymerized 3-dimensional printing materials on 3-dimensional-printed crowns.

INTRODUCTION: The use of 3-dimensional (3D) printing techniques in fabricating crowns has increased the demand for bracket bonding onto these surfaces. The objective was to evaluate the shear bond strength (SBS) of orthodontic brackets bonded onto 3D-printed crowns using primer-incorporated orthodontic adhesives and 3D printing materials as orthodontic adhesives. METHODS: A total of 160 crowns were printed with two 3D printing materials, DentaTOOTH (Asiga, Sydney, Australia) (group A) and NextDent C&B Micro Filled Hybrid (3D Systems, Soesterberg, Netherlands) (group N). Each group was randomly divided into 4 adhesive subgroups (n = 20): Transbond XT (for groups A [ATX] and N [NTX]; 3M Unitek, Monrovia, Calif), Ortho Connect (for groups A [AOC] and N [NOC]; GC Corporation., Tokyo, Japan), Orthomite LC (for groups A [AOM] and N [NOM]; Sun Medical, Co Ltd, Moriyama, Shiga, Japan), and unpolymerized liquid state of 3D printing resin (for groups A [AA] and N [NN]). SBS was measured with a universal testing machine at a crosshead speed of 0.5 mm/min. The adhesive remnant index and the mode of failure were analyzed under the microscope. Statistical analysis was performed at a significance level of α = 0.05. RESULTS: When used as adhesives (AA and NN), 3D printing materials showed no statistically significant difference in SBS compared with Transbond XT (ATX and NTX, respectively). In group N, NN showed a significantly higher SBS than primer-incorporated orthodontic adhesives (NOC and NOM; P <0.001). Adhesive failures were only observed in primer-incorporated orthodontic adhesives (AOC, NOC, AOM, and NOM). CONCLUSIONS: Primer-incorporated orthodontic adhesives, as well as unpolymerized 3D printing materials employed as orthodontic adhesives on 3D-printed crowns, exhibited comparable bonding strength to Transbond XT without surface modification. Despite variations in adhesive-related factors, all measurements stayed within clinically acceptable ranges, highlighting the potential of these materials for orthodontic bonding on 3D-printed crowns, simplifying clinical procedures without compromising bond strength.

Deciphering the functional role of insular cortex stratification in trigeminal neuropathic pain.

Trigeminal neuropathic pain (TNP) is a major concern in both dentistry and medicine. The progression from normal to chronic TNP through activation of the insular cortex (IC) is thought to involve several neuroplastic changes in multiple brain regions, resulting in distorted pain perception and associated comorbidities. While the functional changes in the insula are recognized contributors to TNP, the intricate mechanisms underlying the involvement of the insula in TNP processing remain subjects of ongoing investigation. Here, we have overviewed the most recent advancements regarding the functional role of IC in regulating TNP alongside insights into the IC's connectivity with other brain regions implicated in trigeminal pain pathways. In addition, the review examines diverse modulation strategies that target the different parts of the IC, thereby suggesting novel diagnostic and therapeutic management of chronic TNP in the future.

Dentin abrasion using whitening toothpaste with various hydrogen peroxide concentrations.

PURPOSE: To compare the amount of abrasion of four whitening toothpastes, two conventional toothpastes, and seven experimental toothpastes with varying concentrations of hydrogen peroxide. METHODS: Bovine dentin specimens were treated with the four whitening toothpastes (containing three different concentrations of hydrogen peroxide: 0.75%, 1.50%, and 2.80%), two conventional toothpastes without hydrogen peroxide, seven experimental toothpastes (concentrations of hydrogen peroxide: 0.75%, 1.50%, 3.0%, 4.50%, 6.0%, 7.50%, and 9.0%), and distilled water. After 10,000 strokes of toothbrushing, the amount of abrasion on the dentin surface was measured with a contactless 3D surface profiler (n= 8). The pH of all solutions, the weight percentages of the particles, and the component of particles in the toothpaste were analyzed. The correlations between the dentin abrasion, pH, and weight percentages of the particles in the toothpastes were investigated. RESULTS: The amount of abrasion of the two conventional toothpastes were 1.1-3.6 times higher than those of the four whitening toothpastes. Likewise, the pH of the conventional toothpaste was higher than those of the other whitening toothpastes. No significant differences were found among the four whitening toothpastes. The four whitening toothpastes consisted of a relatively lower weight percentage of particles compared to the two conventional toothpastes. A strong positive correlation was observed between the dentin abrasion and the weight percentages of the particles (r= 0.913; P< 0.05). Furthermore, no significant differences in the amount of abrasion were observed between the specimens treated with seven experimental toothpastes and those treated with distilled water. CLINICAL SIGNIFICANCE: The whitening toothpastes containing less than 9% hydrogen peroxide did not seem to harm the dentin surface significantly. These findings can serve as a reference for consumers, patients, and dental professionals.

Longterm abrasive and erosive effect of whitening toothpaste on dentin surface.

PURPOSE: To evaluate the amount of dentin loss following immersion in or toothbrushing with whitening toothpaste (WT) containing hydrogen peroxide (HP) and citric acid (CA). Additionally, the amount of dentin loss after brushing with a WT alone or in combination with a conventional toothpaste was assessed, and the effects of HP and CA solutions on the dentin surface were investigated. METHODS: Bovine dentin specimens (n= 350) were randomly assigned to seven solutions of various compositions as toothpaste: The specimens assigned to each solution were then further divided into five treatment groups (n=10 each) : Group A = 1-hour immersion in each solution (ES); Group B = 10,000 brushing in ES; Group C = 1-hour immersion in ES + 10,000 brushing in ES; Group D = 1-hour immersion in ES + 10,000 brushing in reference slurry (RS); Group E = 10,000 brushing in ES + 10,000 brushing in RS. The amount and pattern of dentin loss were determined, and the surfaces were observed using noncontact profilometry. RESULTS: The WT (pH 5.0) caused lower dentin loss than RS after a single brushing cycle; however, the extent of dentin loss after 1 hour of immersion in the WT was significantly greater than that in the RS. Among the specimens treated with WT, a significant difference in dentin loss was observed between Group C and Groups D and E (P< 0.05) but not between Groups D and E. The surfaces exposed to CAS1, CAPB, and WT exhibited U-shaped patterns of dentin loss after brushing or immersion, whereas a wedge-shaped pattern was observed in those that underwent brushing with the RS. CLINICAL SIGNIFICANCE: The effects (dentin abrasion) of a whitening toothpaste containing hydrogen peroxide and citric acid when used in combination with a conventional toothpaste were similar to those seen with the continuous use of a conventional toothpaste alone.

Effects of a commercial whitening toothpaste containing hydrogen peroxide and citric acid on dentin abrasion and erosion.

BACKGROUND: Hydrogen peroxide (HP) and citric acid (CA), key contributors to toothpaste acidity, can lead to dental loss. This study aimed to compare the amount of abrasion or loss of dentin based on pH, buffering, and concentration of HP and CA in commercial and experimental toothpastes after toothbrushing or immersion. METHODS: Bovine dentin specimens were randomly assigned to nine solutions. The prepared solutions included two commercial toothpastes (whitening toothpaste [WT] with HP and CA; conventional toothpaste [CT] without HP and CA), reference slurry (RS), two CA solutions (1.92%, CAS1; 0.001%, CAS2), basic solution (7.16% sodium phosphate dibasic [SPDS]), CA phosphate buffer solution (3.58% SPDS and 0.96% CA [CAPB]), HP solution (4%, HPS), and distilled water (DW). Dentin specimens were performed in two treatments: one with only abrasion (10,000 brushings) and one with only immersion (1 h). After treatments, the amount of dentin loss and surface images were measured and observed using noncontact profilometry. Data were analyzed using an one-way analysis of variance and the Tukey test as a post hoc analysis (p < 0.05). RESULTS: WT with pH 5.0 had lower dentin abrasion than CT and RS after brushing but had higher dentin loss than both after immersion. The dentin surfaces of CAS1, CAPB, and WT were damaged after immersion, whereas HPS, CAS2, CT, SPDS, RS, and DW remained intact after soaking. CAS2 and HPS, which had a pH of 5.0 like WT, did not significantly differ from those of DW after brushing. CONCLUSIONS: WT containing HP and CA did not cause significant dentin abrasion but may cause additional dentin loss even without brushing. After brushing or immersion, the CA concentration may affect the dentin surface more than the HP concentration included in WT. The amount of abrasion or loss of dentin after brushing or soaking can vary based on the composition, concentration, and buffer in the solution, even if the pH of the solution is similar to pH 5.0.

Stimulating GABAergic Neurons in the Nucleus Accumbens Core Alters the Trigeminal Neuropathic Pain Responses in a Rat Model of Infraorbital Nerve Injury.

The nucleus accumbens core (NAcc) is an important component of brain reward circuitry, but studies have revealed its involvement in pain circuitry also. However, its effect on trigeminal neuralgia (TN) and the mechanism underlying it are yet to be fully understood. Therefore, this study aimed to examine the outcomes of optogenetic stimulation of NAcc GABAergic neurons in an animal model of TN. Animals were allocated into TN, sham, and control groups. TN was generated by infraorbital nerve constriction and the optogenetic virus was injected into the NAcc. In vivo extracellular recordings were acquired from the ventral posteromedial nucleus of the thalamus. Alterations of behavioral responses during stimulation "ON" and "OFF" conditions were evaluated. In vivo microdialysis was performed in the NAcc of TN and sham animals. During optogenetic stimulation, electrophysiological recordings revealed a reduction of both tonic and burst firing activity in TN animals, and significantly improved behavioral responses were observed as well. Microdialysis coupled with liquid chromatography/tandem mass spectrometry analysis revealed significant alterations in extracellular concentration levels of GABA, glutamate, acetylcholine, dopamine, and citrulline in NAcc upon optic stimulation. In fine, our results suggested that NAcc stimulation could modulate the transmission of trigeminal pain signals in the TN animal model.

Growth patterns and overbite depth indicators of long and short faces in Korean adolescents: Revisited through mixed-effects analysis.

OBJECTIVE: The purpose was to evaluate skeletal factors related to the growth of subjects with skeletal open and deep bites based on lateral cephalographs from 9 years of pure longitudinal data using mixed effect analysis. SETTING AND SAMPLE POPULATION: Fifty-one children with extreme lower anterior facial height to total anterior facial height (LAFH/TAFH) ratio values at the age of 14 were assigned to either skeletal open bite or skeletal deep bite groups from a total of 223 subjects. MATERIAL & METHODS: The palatal plane angle (PPA), mandibular plane angle (MPA), gonial angle (GA), palatomandibular plane angle (PMA), upper gonial angle (UGA), lower gonial angle (LGA), occlusal plane angle (OPA) and overbite depth indicator (ODI) were measured and analysed. Mixed-effects regression model analysis was used for the interpretation of data with random effects. RESULTS: Morphological differences were evident from the beginning and became more pronounced with age in MPA, GA, PMA, ODI and LGA. The initial values of all variables were statistically significant. Annual increases with age were statistically significant in GA, OPA, ODI and UGA. The morphological differences in the annual increases in MPA, GA, PMA and UGA were also statistically significant. CONCLUSIONS: Morphologically different growth patterns were mainly contributed by lower anterior facial height dimensions. The extent of individual variations mandates judicious decision-making in clinical situations.

Augmented reality in dentistry: a current perspective.

Augmentation reality technology offers virtual information in addition to that of the real environment and thus opens new possibilities in various fields. The medical applications of augmentation reality are generally concentrated on surgery types, including neurosurgery, laparoscopic surgery and plastic surgery. Augmentation reality technology is also widely used in medical education and training. In dentistry, oral and maxillofacial surgery is the primary area of use, where dental implant placement and orthognathic surgery are the most frequent applications. Recent technological advancements are enabling new applications of restorative dentistry, orthodontics and endodontics. This review briefly summarizes the history, definitions, features, and components of augmented reality technology and discusses its applications and future perspectives in dentistry.

Time-dependent periimplant bone reaction of acidic monomer-treated injection molded zirconia implants in rabbit tibiae.

PURPOSE: The aim of this study was to evaluate and compare the osseointegration of zirconia implants in rabbit tibiae with and without 10-methacryloyloxydecyl dihydrogen phosphate (MDP) treatment. MATERIALS AND METHODS: Twenty-eight rabbits received a total of 112 external hex-type implants made by the powder injection molding technique with and without MDP treatment before installation in the tibiae. The contact angles on the zirconia implants and zirconia discs before and after MDP application were evaluated. Removal torque (RT) and bone-implant contact (BIC) ratios were measured. RESULTS: The MDP treatment markedly enhanced the hydrophilicity and seemed to alter the topography and chemical composition of the implant and disc surface. As the healing time increases, the BIC and RT were increased in both groups. The MDP-treated implants exhibited higher BIC values than the control implants after 2 and 4 weeks of healing. The RT was higher in MDP-treated implants after 2 weeks of healing but not after 4 weeks of healing. CONCLUSION: The 10-MDP treatments made the surface more hydrophilic and enhanced the osseointegration of the implants in the early healing phase.

Peri-implant bone formation of non-thermal atmospheric pressure plasma-treated zirconia implants with different surface roughness in rabbit tibiae.

OBJECTIVES: The aim of this study was to evaluate and compare the osseointegration of powder-injection molded (PIM) zirconia implants in rabbit tibiae with or without He plasma treatment. MATERIAL AND METHODS: Twenty-five rabbits received 4 types of external hex implants with identical geometry in the tibiae: PIM zirconia implants, roughened PIM zirconia implants, plasma-treated PIM zirconia implants, and plasma-treated roughened PIM zirconia implants. The contact angles of the four types of implants were evaluated. Removal torque tests and histomorphometric analyses were performed. RESULTS: The plasma treatment markedly enhanced the hydrophilicity, but did not seem to change the surface topography of the PIM zirconia implants. There were statistically significant differences in the bone-to-implant contact (BIC) ratios, bone volume (BV/TV), and removal torque values (RTQ) among the tested implant types (P < 0.001). The plasma-treated implants exhibited significantly higher BIC and BV/TV values than the untreated implants. However, the removal torque values favored the rough surface. CONCLUSIONS: The He plasma treatments on PIM zirconia implants made the surface more hydrophilic and enhanced the osseointegration of the implants without changing the micro-topography.

Do long-faced subjects really have a long anterior face? A longitudinal study.

INTRODUCTION: The aims of this study were to investigate and compare the anterior facial heights of children with long, normal, and short faces during growth and to discover whether long-faced subjects have long dimensions in both the upper and lower anterior facial heights compared with the others. METHODS: Longitudinal lateral cephalometric data of 167 children (83 girls, 84 boys) from 6 to 14 years of age were used. Total anterior face height, upper anterior face height, lower anterior face height, and the closest distance from the Frankfort horizontal plane to nasion were measured. The samples were classified as long-faced, normal-faced, and short-faced according to the ratio of lower to total face heights at 14 years old. All data were analyzed statistically and compared between the groups according to age. RESULTS: The mean lower anterior face height in the long-faced group was larger than in the normal-faced and short-faced groups for all ages in both sexes. In contrast, subjects in the normal-faced group had a longer mean upper anterior face height than did subjects in the long-faced and short-faced groups. In addition, the mean upper anterior face height of the short-faced group was larger than the long-faced group for girls at all ages and for boys at 12 to 14 years. CONCLUSIONS: The long-faced children did not have longer upper facial heights compared with normal-faced and short-faced children, and their long faces were mainly determined by the length of the lower face.

Submorphotypes of the maxillary first molar and their effects on alignment and rotation.

INTRODUCTION: The aim of this study was to explore the shape differences in maxillary first molars with orthographic measurements using 3-dimensional virtual models to assess whether there is variability in morphology that could affect the alignment results when treated by straight-wire appliance systems. METHODS: A total of 175 maxillary first molars with 4 cusps were selected for classification. With 3-dimensional laser scanning and reconstruction software, virtual casts were constructed. After performing several linear and angular measurements on the virtual occlusal plane, the teeth were clustered into 2 groups by the method of partitioning around medoids. To visualize the 2 groups, occlusal polygons were constructed using the average data of these groups. RESULTS: The resultant 2 clusters showed statistically significant differences in the measurements describing the cusp locations and the buccal and lingual outlines. The rotation along the centers made the 2 cluster polygons look similar, but there was a difference in the direction of the midsagittal lines. CONCLUSIONS: There was considerable variability in morphology according to 2 clusters in the population of this study. The occlusal polygons showed that the outlines of the 2 clusters were similar, but the midsagittal line directions and inner geometries were different. The difference between the morphologies of the 2 clusters could result in occlusal contact differences, which might be considered for better alignment of the maxillary posterior segment.

The growth trends of Korean adolescents with bialveolar protrusion: a nine year longitudinal cephalometric study.

Bialveolar protrusion and dental crowding seems to have common features in terms of aetiology and treatment method, although they result in different facial profiles and tooth alignment. The aim of this longitudinal study is to determine when children begin to show bialveolar protrusive traits in order to get more clue about the aetiology of bialveolar protrusion. Longitudinal lateral cephalometric data of children followed from 6 to 14 years of age were used. A total of 155 children (81 girls and 74 boys) with showing Class molar relationships at the age of 14 were assigned to either the protrusive group (PG) or the non-protrusive group (NPG), based on 5 cephalometric measurements. The cephalometric measurements of these 2 groups were compared at each age separately in both sexes by independent t-tests. Throughout the entire observation period, there were differences between PG and NPG in both sexes in measurements which were used for classification at 14 years of age. There were differences between sexes in both PG and NPG in several measurements of at several different ages. Individuals with bialveolar protrusive traits at the age of 14 exhibited the signs early in life, at least from the early mixed dentition.

Optogenetic Approach in Trigeminal Neuralgia and Potential Concerns: Preclinical Insights.

The integration of optogenetics in the trigeminal pain circuitry broadens and reinforces existing pain investigations. Similar to research on spinal neuropathic pain, the exploration of the underlying determinants of orofacial pain is expanding. Optogenetics facilitates more direct, specific, and subtle investigations of the neuronal circuits involved in orofacial pain. One of the most significant concerns of both dentistry and medicine is trigeminal neuralgia (TN) management due to its substantial impact on a patient's quality of life. Our objective is to gather insights from preclinical studies conducted in TN employing an optogenetic paradigm, thereby extending the prospects for in-depth neurobiological research. This review highlights optogenetic research in trigeminal pain circuitry involving TN. We outline the central and peripheral regions associated with pain-that have been investigated using optogenetics in the trigeminal pain circuitry. The study further reports its scope and limitations as well as its potential for future applications from bench to bedside.

Whitening Efficacy of Toothpastes on Coffee-Stained Teeth: An Enamel Surface Analysis.

AIM: This study aimed to identify the optimal toothpaste for removing coffee-induced stains while also evaluating its impact on tooth enamel through roughness and abraded depth parameters, providing a comprehensive understanding of their effects. MATERIALS AND METHODS: Three whitening toothpastes and 2 conventional toothpastes were prepared for a simulated brushing procedure on coffee-stained bovine enamel tooth specimens. Using a toothbrushing machine, up to 10,000 brushstrokes were completed, while spectrophotometric readings were taken at designated intervals. A mixed-effects model for statistical analysis determined the effects of toothpaste and brushing on colour change, roughness, and abraded depth. RESULTS: Whitening toothpastes significantly deviated from the control (P < .001, P < .001, and P < .003, respectively), whereas the conventional toothpaste did not exhibit a significant contrast (P < .081). Regarding colour restoration following coffee staining, whitening toothpastes showed higher restoration than conventional toothpastes. Surface roughness and abraded depth parameters increased with accumulated brushing. CONCLUSIONS: Sodium hexametaphosphate-containing toothpaste demonstrated the highest efficacy in removing coffee-induced stains and restoring tooth colour. Nevertheless, this stronger whitening effect was associated with increased abrasion. While conventional toothpastes exhibited some whitening effects, the most substantial improvement in lightness was consistently observed with whitening toothpastes. CLINICAL RELEVANCE: Understanding how whitening toothpaste affects enamel integrity is crucial for refining formulations and advancing dental care. This knowledge lays the groundwork for more effective oral care products and improved whitening procedures, ultimately enhancing the overall quality of dental treatments.

Evaluation of Relative Dentin Abrasivity in Whitening Toothpastes Containing Acids.

INTRODUCTION AND AIMS: This study aimed to evaluate the relative dentin abrasivity of whitening toothpastes containing acids using the Radioactive Dentin Abrasivity - Profilometry Equivalent (RDA-PE). METHODS: A total of 100 bovine dentin specimens were prepared and assigned to the following groups (n = 10): 5 hydrogen peroxide (HP) whitening toothpastes (WTH1-WTH5) with or without acid (citric acid, ethylenedinitrilotetraacetic acid disodium, and phosphoric acid), 2 whitening toothpastes with silica and containing citric or phosphoric acid (WTS1 and WTS2), one conventional toothpaste (CT), and 2 reference slurries (RS). All specimens were brushed for 4,000 or 10,000 strokes using toothbrush and toothbrushing machine. The average dentin depth was measured using a noncontact profilometery, and the RDA-PE value was calculated based on the RS. The pH of the solution, average particle size, particle content, and particle hardness were measured. The RDA-PE data were analysed using one-way analysis of variance and Tukey's test, and the effects of the 4 measured factors on RDA-PE were investigated via multiple regression analysis. RESULTS: The RDA-PE values of the HP whitening toothpastes (mean value: 19-46) were significantly lower, whereas those of the silica whitening toothpastes (80 or 111) were similar to those of the RS after 4,000 strokes (100). The RDA-PE values of all whitening toothpastes were significantly lower than the RS values after 10,000 strokes (242). The HP whitening toothpastes were slightly acidic (pH ≤6) compared to the other solutions. The HP (2.9%-3.7%) and silica (8.9% or 9.9%) whitening toothpastes had significantly lower particle content than RS (16.6%). The particle content significantly influenced the RDA-PE values by multiple regression results. CONCLUSIONS: The RDA-PE values of whitening toothpastes varied. The particle content in the solution was a key factor affecting the RDA-PE value. CLINICAL RELEVANCE: Whitening toothpastes containing acids did not cause significant dentin abrasion.