Effects of Thermocycling with Two Different Curing Techniques on Enamel Micro-Cracks Formation, Debonding, and Failure Modes of Ceramic Brackets: An In Vitro Study.

Despite the rise in popularity of ceramic braces for adults, the risk of enamel microcracks (EMCs) upon removal remains a significant drawback for both dental professionals and patients. Our study aimed to assess the effects of thermocycling, pre-curing, and co-curing techniques with different bonding agents on the enamel surface of teeth after the removal of ceramic brackets. We also examined the incidence, quantity, length, and direction of EMCs on tooth surfaces. Additionally, the adhesive remnant index (ARI) scores and orthodontic bracket bond failure modes were evaluated and compared. The study divided 40 extracted upper canine teeth into ten groups for further analysis. Two groups had intact enamel as the negative control, while the remaining groups had orthodontic ceramic brackets bonded using different bonding agents and curing techniques. Thermocycling was performed in five groups, and ARI was assessed after debonding. The study findings were statistically significant (p < 0.05) in demonstrating the impact of curing techniques on EMCs and debonding outcomes. Seventh-generation bonding agents resulted in complete adhesive removal (ARI = 0). The microcracks' incidence, number, and length showed insignificant results. Differences in ARI between thermocycler and non-thermocycler samples were insignificant. Both co-curing and pre-curing techniques yielded comparable ARI results. This study highlights the importance of using advanced bonding agents to minimize enamel damage during ceramic bracket debonding.

Effectiveness of Two Intensity Levels of Diode Laser in Debonding Metallic Brackets Regarding Enamel Surface Integrity and Pulpal Temperature: An Ex-Vivo Study.

INTRODUCTION: The traditional methods of deboning metal brackets exert excessive force, resulting in enamel scratches, fractures, and patient discomfort. The objective of this study was to evaluate the effectiveness of using two intensity levels of a diode laser for debonding metallic orthodontic brackets as an alternative to the conventional debonding method. MATERIALS AND METHODS: Sixty intact, extracted human premolar teeth were used in this study, and metal orthodontic brackets were bonded to the buccal surface of these teeth. The teeth were divided into three groups for the experiment: (1) the control group, where conventional bracket debonding was performed using a debonding plier, (2) the first experimental group, where a diode laser (2.5W, 980nm) was utilized for laser debonding, and (3) the second experimental group, where a diode laser (5W, 980nm) was used for laser debonding. The laser was applied using a sweeping movement for 5 seconds. After debonding, the adhesive remnant index (ARI), the lengths, and the frequency of enamel cracks were compared among the groups. Additionally, an increase in intra-pulpal temperature was measured. RESULTS: In all groups, there were no instances of enamel fractures. Laser debonding resulted in a significant reduction in both the frequency and length of newly formed enamel cracks compared to the conventional debonding method. The laser debonding group exhibited increases in intra-pulpal temperature of 2.37°C and 3.60°C in the second and third groups, respectively. These temperature increases were significantly lower than the threshold of 5.5°C. There were no significant differences observed in the ARI scores among the groups. CONCLUSION: With all debonding methods, an increase in the length and frequency of enamel cracks should be anticipated. However, laser-assisted debonding of metal brackets offers the advantage of reducing the risk of enamel damage while avoiding thermal damage to the pulp.

Oral Piercing: A Pretty Risk-A Scoping Review of Local and Systemic Complications of This Current Widespread Fashion.

Piercing insertion is a common practice among people of all ages for different reasons (e.g., esthetics, culture, religion). In the oral cavity, the jewel can be placed in the lips, cheeks, tongue, and frenulum. The presence of an oral piercing could cause local and systemic complications in the short term. In the long term, irreversible damage may occur to the hard and soft tissues of the oral cavity. Different authors in the past have produced publications focusing on this issue. This study analyzes 10 published articles sourced from online databases according to the PRISMA flowchart. These articles were chosen from the 501 suitable papers initially found. PubMed, Web of Science, and Scopus were used as the online databases for searching for papers that matched the topic, using the keywords "complication" and "oral piercing". The purpose of this review is to describe and analyze all possible complications related to the presence of a piercing in the mouth. Local and systemic complications are related to the presence of plaque and localized pathogenic micro-organisms that can spread via the bloodstream, although they rarely occur in patients without predisposing conditions. Maintaining proper oral hygiene and frequent check-ups are essential to avoid the onset of complications.

Recent Advances in the Diagnosis of Enamel Cracks: A Narrative Review.

Cracked teeth can pose a diagnostic dilemma for a clinician as they can mimic several other conditions. The constant physiological stress along with any pathological strain like trauma or iatrogenic causes can lead to the development of microcracks in the teeth. Constant exposure to immense stress can cause the progression of these often-undiagnosed tooth cracks to cause tooth fractures. This review aims to outline the etiology of tooth cracks, their classification, and recent advances in the diagnosis of enamel cracks. Diagnosing a cracked tooth can be an arduous task as symptoms differ according to the location and extension of the incomplete fracture. Early detection is critical because restorative treatment can prevent fracture propagation, microleakage, pulpal or periodontal tissue involvement, and catastrophic cusp failure. Older methods of crack detection are not sensitive or specific. They include clinical examination, visual inspection, exploratory excavation, and percussion test. The dye test used blue or gentian violet stains to highlight fracture lines. Modern methods include transillumination, optical coherence tomography Swept-Source Optical Coherence Tomography (SSOCT), near-infrared imaging, ultrasonic system, infrared thermography, and near-infrared laser. These methods appear to be more efficacious than traditional clinical dental imaging techniques in detecting longitudinal tooth cracks. Clinically distinguishing between the various types of cracks can be difficult with patient-reported signs and symptoms varying according to the location and extension of the incomplete fracture. Cracks are more common in restored teeth. Technological advances such as transillumination allow for early detection and enhanced prognosis.

Use of optical coherence tomography in orthodontics.

Optical coherence tomography (OCT) is a modern imaging method with applicability in orthodontics. In recent years, there has been an increasing trend in the use of ceramic brackets. The aim of the present study was to investigate the effects of bonding metallic and ceramic brackets on tooth enamel, using optical coherence tomography. For this purpose, 20 permanent teeth we bonded and were subsequently debonded using a side cutter or anterior bracket removal pliers. Using the OCT technique, the enamel, the amount of adhesive remaining and the bracket fragments remaining on the tooth surface were analyzed following the debonding procedure. It was demonstrated that enamel cracks were present only in the samples bonded with ceramic brackets. At the same time, it was noted that the type of pliers did not affect the incidence and extent of damage to the enamel. The type of debonding technique (using the side cutter or the anterior removal pliers) used did not markedly affect the amount of adhesive remaining on the teeth. Thus, as demonstrated herein, by analyzing the enamel structure through the use of OCT, the quality of the processes and the materials used for manufacturing brackets can be increased.

Comparative evaluation of the efficacy of the desensitizing and remineralizing agent in the reduction of dentin hypersensitivity after orthodontic debonding - a randomized clinical trial.

INTRODUCTION: Enamel loss is a common problem during various orthodontic procedures. The study aims to compare the efficacy of a desensitizer and remineralizer in the reduction of the dentin hypersensitivity (DH) associated with enamel microcracks after orthodontic debonding. METHODS: A unicentric two arm parallel study with 30 subjects randomly assigned to each groups following debonding. Group-1 subjects were treated with Gluma® desensitizer (5% glutaraldehyde and 35% hydroxyethyl methacrylate (HEMA)) and the Group-2 intervention included a remineralizing agent GC Tooth Mousse Plus® (casein phospho peptide and amorphous calcium Fluro phosphate (CPP:ACFP)). The Visual Analogue Scale (VAS) was utilized to evaluate DH as subjective perception of pain following the Air blast test and Cold test. The VAS scale was indexed from 0-10 markings based on the intensity of perception. Five different time points T0 and T1 - immediately after debonding and intervention on day 1, T2 - 48 hours, and T3 after 72 hours were taken for the assessment of VAS scores. RESULTS: The VAS scores for the airblast test for group 1 were (2.73, 0, 0.06, 0.03) and group 2 (2.46, 0, 0.16, 0.13) at different periods. The sensitivity scores for the cold blast test for group 1 were (2.73, 0, 0.13, 0.03) and for group 2 (2.46, 0, 0.16, 0.13). There was 98 percent reduction in DH between T0 and T3 and was statistically significant (p<0.05) for both the groups. CONCLUSION: Gluma® desensitizer and GC Tooth Mousse Plus® are equally effective in the reduction of DH in the orthodontic patient following debonding.

Effect of different debonding techniques on shear bond strength and enamel cracks in simulated clinical set-ups.

OBJECTIVE: The aim of this study was to evaluate the relationship between debonding forces and enamel cracks length change between different debonding techniques. METHODS: 80 extracted premolar teeth with intact buccal enamel were divided into five groups. In each group, enamel cracks were evaluated by stereomicroscope before and after debonding. All teeth were bonded with metal brackets by self-cure adhesive (3M, USA) and then debonded by bracket debonding plier, fixed on the UTM machine, through five methods based on location of plier on brackets: OGwing (occlusogingival), MDwing (mesiodistal), Oblique, OGbase (occlusogingival) and Cusp-base. RESULTS: Based on non-parametric distribution of data, there was no significant difference between groups in ARI and enamel cracks length change. The highest shear bond strength for debonding presented in OG base method (25.25 ± 8.4) and the difference was statistically significant (P-value = 0.029). There was no linear relationship between shear bond strength and cracks length change and also between ARI and cracks length change. CONCLUSION: Despite the lower cracks length change in Cusp-base method than other groups, there wasn't significant difference between debonding methods. Also the amount of debonding forces and ARI do not affect the changes of cracks length.

Molar cusp deformation evaluated by micro-CT and enamel crack formation to compare incremental and bulk-filling techniques.

OBJECTIVES: To describe a method of measuring the molar cusp deformation using micro-computed tomography (micro-CT), the propagation of enamel cracks using transillumination, and the effects of hygroscopic expansion after incremental and bulk-filling resin composite restorations. METHODS: Twenty human molars received standardized Class II mesio-occlusal-distal cavity preparations. They were restored with either a bulk-fill resin composite, X-tra fil (XTRA), or a conventional resin composite, Filtek Z100 (Z100). The resin composites were tested for post-gel shrinkage using a strain gauge method. Cusp deformation (CD) was evaluated using the images obtained using a micro-CT protocol and using a strain-gauge method. Enamel cracks were detected using transillumination. RESULTS: The post-gel shrinkage of Z100 was higher than XTRA (P < 0.001). The amount of cusp deformation produced using Z100 was higher compared to XTRA, irrespective of the measurement method used (P < 0.001). The thinner lingual cusp always had a higher CD than the buccal cusp, irrespective of the measurement method (P < 0.001). A positive correlation (r = 0.78) was found between cusp deformation measured by micro-CT or by the strain-gauge method. After hygroscopic expansion of the resin composite, the cusp displacement recovered around 85% (P < 0.001). After restoration, Z100 produced more cracks than XTRA (P = 0.012). CONCLUSIONS: Micro-CT was an effective method for evaluating the cusp deformation. Transillumination was effective for detecting enamel cracks. There were fewer negative effects of polymerization shrinkage in bulk-fill resin restorations using XTRA than for the conventional incremental filling technique using conventional composite resin Z100. CLINICAL SIGNIFICANCE: Shrinkage and cusp deformation are directly related to the formation of enamel cracks. Cusp deformation and crack propagation may increase the risk of tooth fracture.

Assessment of enamel cracks at adhesive cavosurface margin using three-dimensional swept-source optical coherence tomography.

OBJECTIVES: Swept-source optical coherence tomography (SS-OCT) can construct cross-sectional images of internal biological structures. The aim of this study was to evaluate enamel cracks at the cavosurface margin of composite restorations using SS-OCT. METHODS: Bowl-shaped cavities were prepared at two locations (mid-coronal and cervical regions) on the enamel surface of 60 bovine teeth. Half of the cavities (30) were treated with phosphoric acid gel. A two-step self-etch adhesive (Clearfil SE Bond) was applied to all cavities and a flowable composite was placed in bulk. After 7days in water at 37°C, three-dimensional (3D) images of the specimens were obtained using SS-OCT, and cross-sectional views of the cavosurface margin were examined. Presence and extent of enamel cracks along the cavosurface margin circumference were evaluated using a 5-point scale. The results were statistically compared with Wilcoxon rank sum test with Bonferroni correction. RESULTS: 3D SS-OCT could detect enamel cracks at the cavosurface margin of composite restorations. Cervical regions caused more enamel cracking than mid-coronal regions. Phosphoric acid etching increased the incidence of enamel cracks compared with the preparations without etching. CONCLUSION: SS-OCT can be used to detect enamel cracks at the margins of composite restorations noninvasively. Presence and extent of enamel cracks depended on the enamel region and bonding protocol. CLINICAL SIGNIFICANCE: SS-OCT can be used to detect enamel cracks at the margins of composite restorations noninvasively. Selective phosphoric acid etching of the enamel significantly increased the incidence of marginal cracks, especially in cervical preparation.

A Novel Biomimetic Approach to Repair Enamel Cracks/Carious Damages and to Reseal Dentinal Tubules by Amorphous Polyphosphate.

Based on natural principles, we developed a novel toothpaste, containing morphogenetically active amorphous calcium polyphosphate (polyP) microparticles which are enriched with retinyl acetate ("a-polyP/RA-MP"). The spherical microparticles (average size, 550 ± 120 nm), prepared by co-precipitating soluble Na-polyP with calcium chloride and supplemented with retinyl acetate, were incorporated into a base toothpaste at a final concentration of 1% or 10%. The "a-polyP/RA-MP" ingredient significantly enhanced the stimulatory effect of the toothpaste on the growth of human mesenchymal stem cells (MSC). This increase was paralleled by an upregulation of the MSC marker genes for osteoblast differentiation, collagen type I and alkaline phosphatase. In addition, polyP, applied as Zn-polyP microparticles ("Zn-a-polyP-MP"), showed a distinct inhibitory effect on growth of Streptococcus mutans, in contrast to a toothpaste containing the broad-spectrum antibiotic triclosan that only marginally inhibits this cariogenic bacterium. Moreover, we demonstrate that the "a-polyP/RA-MP"-containing toothpaste efficiently repairs cracks/fissures in the enamel and dental regions and reseals dentinal tubules, already after a five-day treatment (brushing) of teeth as examined by SEM (scanning electron microscopy) and semi-quantitative EDX (energy-dispersive X-ray spectroscopy). The occlusion of the dentin cracks by the microparticles turned out to be stable and resistant against short-time high power sonication. Our results demonstrate that the novel toothpaste prepared here, containing amorphous polyP microparticles enriched with retinyl acetate, is particularly suitable for prevention/repair of (cariogenic) damages of tooth enamel/dentin and for treatment of dental hypersensitivity. While the polyP microparticles function as a sealant for dentinal damages and inducer of remineralization processes, the retinyl acetate acts as a regenerative stimulus for collagen gene expression in cells of the surrounding tissue, the periodontium.

Polymerization shrinkage and spherical glass mega fillers: effects on cuspal deflection.

PURPOSE: The Authors analyzed the effect of spherical glass mega fillers (SGMF) on reducing contraction stress in dental composite resins, by means of a cavity model simulating the cuspal deflection which occurs on filled tooth cavity walls in clinical condition. MATERIALS AND METHODS: 20 stylized MOD cavities (C-factor = 0.83) were performed in acrylic resin. The inner surface of each cavity was sand blasted and adhesively treated in order to ensure a valid bond with the composite resin. Three different diameter of SGMF were used (i.e. 1, 1,5, 2 mm). The samples were divided in 4 groups of 5 each: Group 1 samples filled with the composite only; Group 2 samples filled with composite added with SGMFs, Ø1mm (16 spheres for each sample); Group 3 samples filled with composite added with SGMFs, Ø1,5 mm (5 spheres for each sample); Group 4 samples filled with composite added with SGMFs, Ø2 mm (2 spheres for each sample). Digital pictures were taken, in standardized settings, before and immediately after the polymerization of the composite material, placed into the cavities. With a digital image analysis software the distances from the coronal reference points of the cavity walls were measured. Then the difference between the first and second measurement was calculated. The data were analyzed by means of the ANOVA test. RESULTS: A significative reduction on cavity walls deflection, when the composite resin is used in addiction with the SGMFs was observed. The SGMFs of smallest diameter (1mm) showed the better outcome. CONCLUSION: The SGMFs are reliable in reducing contraction stress in dental composite resins.