Orthodontic Reasons Research Articles

CHARACTERISTICS OF THE GINGIVAL EPITHELIUM OF CHILDREN’S THIRD MOLARS AT DIFFERENT STAGES OF ROOT FORMATION

Extraction of impacted and dystopic third molars is a rather traumatic manipulation accompanied by a large bone defect and wound infection. Therefore, it is advisable to perform hermectomy, which has a number of advantages over typical and atypical methods of tooth extraction. An important stage of any surgical intervention is the postoperative period, which is characterized by a certain duration and the presence of complications, which is due, among other things, to the regenerative potential of tissues, especially epithelial tissues. Aim of the study is to evaluate the condition of the gingival epithelium in the area of third molars in children who have to have these teeth extracted for orthodontic reasons, taking into account the stage of tooth formation, i. e. its root.Material and Methods. Third molar extraction for orthodontic indications was performed in 95 children aged 11 to 18 years.Clinical and radiologic examinations were performed in three groups: Group I (n=30) – children aged 11-13 years; Group II(n=35) – children aged 13-16 years, and Group III (n=30) – children aged 16-18 years. During surgery, gingival tissue was taken from the adjacent areas for examination. The material was fi xed, dehydrated, and paraffi n- embedded for histologic processing. Immunohistochemical techniques were performed according to the manufacturer’s protocols. Specifi cally, immunohistochemical detection of Ki-67 antigen was performed with primary antibodies against it. Digital copies of the images were analyzed using the specialized computer program ImageJ v1.52 (freeware, USA). The obtained digital data were statistically processed.The digital data obtained were statistically processed. A preliminary test for normality of the distribution was carried outusing the Shapiro- Wilks method. According to this criterion, the hypothesis of normality of the distribution was not rejectedfor all the statistical samples studied (at the signifi cance level of p=0.05), so we used mainly parametric methods of statistical analysis: calculation of the arithmetic mean and its error, unpaired two-sided Student’s t-test. However, because the statistical samples were small, the non-parametric Mann- Whitney test was used in addition to the Student’s t-test.The study was conducted as part of the complex research work of the Department of Pediatric Dentistry of the Bukovinian State Medical University on the topic «Development of methods of prevention and treatment of the main dental diseases in children, taking into account the risk factors of their development» (state registration number: 0121U110122). The conducted research complied with bioethical norms, as stated in the conclusions of the Bioethics Commission of the Bukovinian State Medical University (№ 1 dated 17.09.2020).Conclusions. Thus, the histological and immunohistochemical study of the gingiva in the area of the third molar allows usto conclude that during the formation of the root of this tooth, a number of changes occur in the epithelial cover of the gingiva, namely: an increase in the number of epithelial layers with a decrease in their proliferative activity. The obtained data indicate a decrease in the regenerative potential of the multilayered squamous epithelium with increasing age of the child and the degree of third molar formation, which is refl ected in the clinical picture of the course of surgical intervention.

A Comparative Analysis of the Occluding Effects on Dentinal Tubules With the Use of Er:YAG Laser and a Commercially Available Desensitizing Agent: An In Vitro Scanning Electron Microscopic Study.

Objective This in vitro scanning electron microscopic (SEM) study aimed to compare the effect of Er:YAG laser and a commercially launched dental productnamely 8% arginine-calcium carbonate on exposed dentinal tubules. Materials and methods A total of 120 tooth samplesprepared from healthy maxillary first premolars extracted due to orthodontic reasons were grouped randomly into four groups of 30 samples each - Group I: control group (C); Group II: laser group (LG); Group III: toothpaste group (TP) and Group IV: laser + toothpaste group (LT). The samples in Group II-IV were treated with the respective test agents and were placed under SEM to study the changes in the dentinal tubule number and diameter. The data obtained from SEM were then subjected to statistical analysis using an unpaired t-test. Results The unpaired t-test revealed extreme statistical differences in means between the test and the control groups and among the test groups (p<0.0001).The results we obtained within the scope of this study showed that both the Er:YAG laser (1.3 W, 100 mJ, 3 Hz, 60 s twice) and dentifrice containing 8% arginine-calcium carbonate as the main ingredient can significantly reduce the number and diameter of the open dentinal tubules. Conclusion Our findings have demonstrated that boththe 8% arginine-calcium carbonate technology and Er:YAG lasersuccessfully reduced the number and diameter of the open dentinal tubules and hence can bepromising agents to deal with dentinal hypersensitivity in future clinical studies.

In Vitro Comparison of Shear Bond Strength (SBS) of Orthodontic Brackets Bonded with 4 Adhesive Materials and Debonded at Different Time Intervals

Aim: This study compared the SBS of orthodontic brackets that were bonded on buccal enamel of premolars either with composite resins or with RMGI after 2 and 24 hours and after 4 weeks. Methods: 220 premolars extracted due to orthodontic reasons were divided in four groups: In 2 groups brackets were bonded with composite resins: GC connect and Transbond XT-3M, and in 2 groups with RMGI: GC FUJI LC Capsule and GC Automix. Each group was divided to 3 different time intervals: 2H, 24H and 4 weeks. At each time interval the brackets were tested using a constant load of 2.5 N and the shear bond strength recorded as stress at maximal load was recorded in MPa. Results: Our study shows that the RMGI glue GC LC Capsule had the highest shear bond strength after 2H (11.6 MPa) and after 24H (8.5 MPa) with significance of P&lt;0.001 Conclusions: As shown also in previous studies GC Fuji LC Capsule should be considered as a safe material for bracket bonding and caries protection during orthodontic treatment, due to fluoride release around the bracket.

Evaluation of the color stability of attachments made with different resin composites

Coloring solutions-such as coffee and cola, frequently consumed daily-cause coloration of attachments made with resin composites. This may reduce the motivation for clear aligner treatment, often preferred by patients with esthetic concerns. This study aimed to compare color changes of orthodontic attachments made with 3 different composite resins. A total of 90 premolar teeth (n= 10) extracted for orthodontic reasons were used. All teeth were embedded in plaster models to imitate the arch shape and scanned with an intraoral scanner. Horizontal rectangular attachments were placed on each tooth by printing the attachment template obtained using digital models. Three composite resins: Omnichroma, GC Aligner Connect, and Tetric PowerFlow were used to prepare the attachments. The models prepared in arc-shaped in each composite group were divided into subgroups and kept in 3 different solutions (coffee, cola, and distilled water) in the incubator at 37 ± 1°C. The models were photographed at baseline and 28 days later with the Smile-Lite MDP device. L, a, and b values were obtained with Digital Color Meter (version 5.22; Apple, Cupertino, Calif). CIEDE2000 formula (ΔE00) was used to evaluate color changes. In addition, models were scanned for color determination at baseline and 28 days later with the 3Shape intraoral scanner. There were significant color differences between solutions (P<0.05). Attachments can be colored easily. Patients should be warned against coloring solutions at the beginning of the treatment, and their eating and drinking habits should be regulated.

A comparison of bond strength and adhesive remnant index of 3D-printed and metal orthodontic brackets attached using different adhesives

Abstract Introduction The aim of this in vitro study was to evaluate the shear bond strength (SBS) and adhesive remnant index (ARI) scores of two different adhesive applications of aesthetic brackets produced from permanent crown material using 3D-printing technology. Methods Sixty maxillary premolar teeth extracted for orthodontic reasons were divided into two main groups according to the type of bracket (metal brackets n=30, 3D-printed brackets n=30) and further divided into two subgroups according to the type of adhesive (flowable composite, Tokuyama SuperLow; non-flowable composite; 3M Transbond XT). SBS and ARI score evaluations were conducted in the experimental and control subgroups (n=15). Statistical analysis was performed by a one-way analysis of variance, a post-hoc test, and Fisher’s exact test. Statistical significance was accepted as P &lt; 0.05. Results The bond strength of the specimens was significantly affected by the type of composite and bracket type (P &lt; 0.001). However, the SBS values were within or above the desired range for orthodontic treatment in all groups. The highest SBS value was obtained in the Metal Bracket-Transbond XT group (15.03 ± 6.66), while the lowest SBS value was observed in the 3D-Printed Bracket-Transbond XT group (7.91 ± 3.07). It was noted that of all materials evaluated, the most common non-enamel-damaging adhesive–cohesive fractures were in 3D-Printed Bracket Tokuyama SuperLow group (n=13). Conclusions It is recommended that 3D-printed orthodontic brackets have sufficient and acceptable SBS levels for clinical applications and bonding using non-flowable adhesives to produce high SBS values and using flowable adhesives generating high ARI scores.

Comparison of Different Rotary Nickel–titanium Systems to Evaluate Coronal Leakage of Root Canals: An in Vitro Study

Introduction: The objective of the study was to assess coronal leakage following root canal treatment utilizing four Micro Mega rotary nickel–titanium files, specifically One shape, Two shape (s1), Two shape (s2), and Revo-S, by means of dye penetration analysis using a stereomicroscope set at 20× magnification. Methods: Fifty human lower premolar teeth that were extracted for orthodontic reasons were included in the study, excluding teeth with cracks, caries, severe curvature (&lt;25°), or root resorption. The teeth were randomly assigned to five groups using www.random.org, and standard endodontic treatments were performed as per the manufacturer’s instructions using Micro Mega One shape, Two shape (s1), Two shape (s2), and Revo-S rotary nickel–titanium systems. To measure dye penetration, the teeth were immersed in a 2% methylene blue dye solution for approximately 24 hours and then axially split using a diamond sectioning disc, with measurements taken using a stereomicroscope. Results: The study groups showed statistically significant differences (P &lt; 0.001), and all pairwise comparisons were found to be significantly different according to the post hoc test (P &lt; 0.001). Conclusion: Our results showed that various rotary file designs significantly affect coronal leakage.

Multimodal Imaging of Dental Pulp Healing Patterns Following Tooth Autotransplantation and Regenerative Endodontic Treatment

IntroductionUnderstanding the healing process of dental pulp after tooth autotransplantation (TAT) and regenerative endodontic treatment (RET) of immature teeth is important both clinically and scientifically. This study aimed to characterize the pattern of dental pulp healing in human teeth that underwent TAT and RET using state-of-the-art imaging techniques. Materials and MethodsThis study examined 4 human teeth, 2 premolars that underwent TAT, and 2 central incisors that received RET. The premolars were extracted after 1 year (case 1) and 2 years (case 2) due to ankylosis, while the central incisors were extracted after 3 years (cases 3 and 4) for orthodontic reasons. Nanofocus x-ray computed tomography was used to image the samples before being processed for histological and immunohistochemical analysis. Laser scanning confocal second harmonic generation imaging (SHG) was used to examine the patterns of collagen deposition. A maturity-matched premolar was included as a negative control for the histological and SHG analysis. ResultsAnalysis of the 4 cases revealed different patterns of dental pulp healing. Similarities were observed in the progressive obliteration of the root canal space. However, a striking loss of typical pulpal architecture was observed in the TAT cases, while a pulp-like tissue was observed in one of the RET cases. Odontoblast-like cells were observed in cases 1 and 3. ConclusionsThis study provided insights into the patterns of dental pulp healing after TAT and RET. The SHG imaging sheds light on the patterns of collagen deposition during reparative dentin formation.

A Split-Mouth Clinical Comparative Evaluation of the Anesthetic Efficacy of Articaine and Lignocaine for Maxillary Bicuspids Extraction.

Aim The study compared the anesthetic effectiveness of articaine and lignocaine when premolars are extracted bilaterally for orthodontic purposes. Material and methods This prospective split-mouth study was performed on 30 cases selected from orthodontic referral patients reporting to the Oral and Maxillofacial Surgery Department at Maharaja Ganga Singh Dental College and Research Center, Rajasthan, India, for bilateral extraction of premolars under local anesthesia. We used 4% articaine hydrochloride and adrenaline 1:100000 (AH) as group A and 2% lignocaine hydrochloride with adrenaline 1:100000 (LH) on the control side as group B. For premolar anesthetization, 0.6-1.6 ml of AH and 1-2 ml of LH were injected submucosally in the buccal vestibular area. The extraction procedure was then carried out after achieving adequate anesthesia. The pain was assessed with Visual Analog Scale. The average onset time and duration of anesthesia were recorded. Data collected were summarized with descriptive statistics.The SPSSversion 23.0 (IBM Corp., Armonk, New York) was used for data entry, validation, and analysis. Means of continuous variables were compared using the student t-test. All tests were 2-tailed and significant at equal or less than 0.05. (p≤0.05). Results When comparing the overall anesthetic efficiency, Group A had a lower overall pain score of 0.43 while Group B had a higher overall pain score of 2.9. The average onset time of anesthesia in Group A was 1.2 minutes and 2.55 minutes in Group B. In Group A, the average duration of anesthesia was 70 minutes, and 46.5 minutes in Group B. These parameters were statistically significant with a p-value of <0.05. Conclusion The study concluded that as an alternative to lignocaine, articaine could be used effectively for maxillary premolar extractions for orthodontic reasons obviating palatal injection which is very painful to the patient.

Antimicrobial Efficacy of Two Different Calcium Hydroxide Endodontic Dressings on the Eradication of Enterococcus faecalis in Single-Rooted Canals: An In Vitro Study.

Bacterial pulp infections are considered the most common cause of endodontic treatment failure. Enterococcus faecalis was isolated from most cases of failure of endodontic treatment. Therefore, using the appropriate intra-canal dressing is essential for successful treatment. The improved formula used in calcium hydroxide PLUS points ensures more calcium hydroxide is released over a longer period and more space to release calcium hydration. This in vitro research aimed to evaluate the differences in the efficacy between Ca(OH)2paste and PLUS points as an endodontic dressing in eradicating E. faecalis growth inside infected single-rooted canals. Thirty mandibular first premolars with single canals were extracted for orthodontic reasons and were prepared after cutting their crowns to standardize the length of the roots to 17 mm, root preparation, and isolating E. faecalis. The infected sample root canals were contaminated with the prepared bacterial suspension, and the sample was incubated in the incubator under air conditions at 37°C for seven days, counting the bacteria colonies. Then, the bacterial units were counted before applying the drug, applying Ca(OH)2 paste in the first group and Ca(OH)2 PLUS points in the second group. The bacterial units were counted, and the number of bacteria was compared between the two substances applied to the samples, measuring the intracanal dressings' effectiveness. Wilcoxon signed-rank tests were used to detect significant differences. Results: The results showed a statistically significant difference in the bacterial count of E. faecalis before and after applying the dressing of Ca(OH)2 paste from a mean of 11.89 to a mean of 3.18 (p=0.003) and no statistical difference in applying Ca(OH)2 PLUS points from mean 11.98 to mean 10.50 (p>0.05). Within the limits of the current in vitro study, the Ca(OH)2 paste cones were more effective than Ca(OH)2 PLUS points in eradicating E. faecalis growth inside the infected single-rooted canals.

Evaluation of the efficacy of topical rifamycin application on postoperative complications after lower impacted wisdom teeth surgery

PurposeThis study aimed to evaluate the efficacy of a single-dose topical rifamycin application on postoperative complications after impacted lower third molar surgery. Materials and methodsThis prospective, controlled clinical study consisted of individuals with bilaterally impacted lower third molars that would be extracted for orthodontic reasons. The extraction sockets were irrigated with 3 ml/250 mg of rifamycin solution in Group 1, while in Group 2 (control group) the extraction sockets were irrigated with 20 ml of physiological saline. Pain intensity was measured daily for 7 days by using visual analog scale. Trismus and edema were evaluated preoperatively and on the postoperative days 2 and 7 by calculating the proportional changes in maximum mouth opening and mean distance between reference points of the face, respectively. Paired samples t-test, Wilcoxon signed rank test and Chi-square test were used to analyze the study variables. Results35 patients (19 female, 16 male) were included in the study. The mean age of all participants was 22.19±4.98. Alveolitis was observed in 8 patients, (6 in the control group, 2 in the rifamycin group). There was no statistically significant difference between groups in terms of trismus and swelling measurements on the 2nd and 7th postoperative days (p>0.05). VAS scores were significantly low in rifamycin group on postoperative days 1 and 4 (p<0.05). ConclusionWithin the limits of the present study, topical rifamycin application reduced the incidence of alveolitis, prevented infection, and provided analgesic effect after surgical removal of impacted third molars.

Vía catecolaminérgica antiinflamatoria en pulpa dental y su relación con el control del dolor durante el manejo complementario con electroacupuntura: un estudio de cohorte

Acupuncture can control inflammation and pain by modulating various neuroimmunological communication pathways, including a catecholamine-dependent pathway. On the other hand, it has been reported that there are nerve terminals of the sympathetic nervous system in the dental pulp and these nerves can control the blood flow in the dental pulp. This study aimed to determine if acupuncture has an analgesic effect on the dental pulp and the relationship with neuroimmunological control elements in this tissue. A prospective cohort study was carried out with patients scheduled for tooth extraction for orthodontic reasons, which were treated with complementary management of electroacupuncture during the extraction process (n = 17). The success of dental anesthesia was determined using electrical tests and postoperative pain scales. In addition, the presence of the α2 adrenergic receptor in cells of immune lineage in dental pulp was determined by fluorescence microscopy. The results showed that complementary therapy with electroacupuncture has a success rate of 72.5%. In addition, cells of immune lineage in dental pulp expressed α2 adrenergic receptors. Consequently, the anatomical and molecular elements in the dental pulp related to catecholaminergic neuroimmune control are present. These anatomical and molecular elements may be related to pulp anesthesia and pain control during tooth extraction.

Fatigue performance of endodontically treated molars reinforced with different fiber systems.

The aim was to investigate the fatigue performance of root canal-treated (RCT) molars restored with different direct restorations utilizing discontinuous and continuous fiber-reinforced composite (FRC) systems. The impact of direct cuspal coverage was also evaluated. One hundred and twenty intact third molars extracted for periodontal or orthodontic reasons were randomly divided into six groups (n=20). Standardized MOD, regular cavities for direct restorations were prepared in all specimens, and subsequently, root canal treatment and root canal obturation was carried out. After the endodontic treatment, the cavities were restored with different fiber-reinforced direct restorations as follows: SFC group (control), discontinuous short fiber-reinforced composite (SFC) without cuspal coverage (CC); SFC+CC group, SFC with cuspal coverage; PFRC group, transcoronal fixation with continuous polyethylene fibers without CC; PFRC+CC group, transcoronal fixation with continuous polyethylene fibers with CC; GFRC group, continuous glass FRC post without CC; and GFRC+CC, continuous glass FRC post with CC. All specimens underwent a fatigue survival test in a cyclic loading machine until fracture occurred or 40,000 cycles were completed. The Kaplan-Meier survival analysis was conducted, followed by pairwise log-rank post hoc comparisons between the individual groups (Mantel-Cox). The PFRC+CC group was characterized by significantly higher survival compared to all the groups (p < 0.05), except for the control group (p = 0.317). In contrast, the GFRC group showed significantly lower survival compared to all the groups (p < 0.05), except for the SFC+CC group (p = 0.118). The control group (SFC) showed statistically higher survival than the SFRC+CC group (p < 0.05) and GFRC group (p < 0.05), but it did not differ significantly from the rest of the groups in terms of survival. Direct restorations utilizing continuous FRC systems (in the form of polyethylene fibers or FRC post) to restore RCT molar MOD cavities performed better in terms of fatigue resistance when CC was performed compared to the same FRC restorations without CC. On the contrary, teeth restored with SFC restorations performed better without CC compared to the ones where SFC was covered. In the case of fiber-reinforced direct restorations for MOD cavities in RCT molars, direct CC is recommended when utilizing long continuous fibers for reinforcement, however, should be avoided when only SFC is used for their reinforcement.

Apoptosis in physiological root resorption of primary teeth.

During physiological root resorption of deciduous teeth, apoptotic cell death triggered by physiological processes might play a role in physiological root resorption in addition to collagen destruction. Little information has been obtained about the sequence of events and the mechanism responsible for the physiological death of pulp tissue cells. This study evaluated apoptotic cell death in the pulp tissue of deciduous teeth that showed various levels of physiological root resorption. The role of apoptosis in pulp tissue elimination during the physiological resorption of deciduous teeth was also examined. For orthodontic reasons, 12 healthy permanent teeth and the pulp of 34 healthy deciduous teeth showing signs of early and advanced root resorption were extracted. To detect apoptotic cells in the pulp tissue, the terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) method and transmission electron microscopy (TEM) were used. The apoptotic index (AI) values of the study groups were determined using the TUNEL method. This technique required calculating the Apoptag positive(+) fibroblast cell ratio in accordance with the total number of cells. No statistically significant differences were found for the AI values of each study group (p>0.05). Apoptosis was detected in the vascular endothelial cells, the mononuclear inflammatory cells, and the odontoblasts of the connective pulp tissue. In the pulp tissue, evaluated using TEM, various pulp cells were observed at distinct stages of apoptosis. The similarity between the AI values for both study groups suggested that in early and advanced stages of resorption, apoptosis may contribute to the regulation of the pulp cell population in a way that does not relate to the physiological process of deciduous teeth root resorption.

Evaluation on the efficacy of processed hydrated and dehydrated amnion chorion membrane on the proliferation of periodontal ligament fibroblasts.

The purpose of the present study was to process and assess the effect of hydrated amnion chorion membrane and dehydrated amnion chorion membrane on proliferation of periodontal ligament(PDL) fibroblast cells. The amnion chorion membrane(ACM) from placenta of 18 systemically healthy patients was obtained from the Department of Obstetrics and Gynaecology. Theywere processed as hydrated and dehydrated based on different processing methods. ThePeriodontal ligament cells were obtainedfrom periodontal ligament offreshly extracted premolars of systemically healthy patients, due to orthodontic reasons. The PDL cells werefurthercultured in laboratory and were exposed to hydrated and dehydrated amnion chorion membrane.The MTT assay was performed to assess the proliferation of PDL fibroblast cells after 24and 48 h. The hydrated and dehydrated amnion chorion membrane showed proliferation of PDL fibroblasts after 24 and 48h. The proliferation of PDL fibroblasts in hydrated (p = 0.043) and dehydrated (p = 0.050) amnion chorion membrane was statistically significant at the end of 24 and 48h respectively.On inter-groupcomparison dehydrated ACM showed significant proliferation of PDL fibroblasts after 24 (p=0.014)and 48 h (p=0.019).Withinthe limits of the present study, it can be concluded: both hydrated and dehydrated amnion chorion membrane showed proliferationof PDL fibroblast cells. However, dehydrated ACM showed significant proliferation of PDL fibroblasts.

Evaluation of Resin Infiltration, Fluoride and the Biomimetic Mineralization of CPP-ACP in Protecting Enamel after Orthodontic Inter-Proximal Enamel Reduction

This study investigated the effect of using different agents for protecting enamel proximal surfaces against acidic attack after interproximal reduction (IPR) using the trans micro radiography technique. Seventy-five sound-proximal surfaces were obtained from extracted premolars for orthodontic reasons. All teeth were measured miso-distally and mounted before being stripped. The proximal surfaces of all teeth were hand stripped with single-sided diamond strips (OrthoTechnology, West Columbia, SC, USA) followed by polishing via Sof-Lex polishing strips (3M, Maplewood, MN, USA). Three-hundred micrometers of enamel thickness was reduced from each proximal surface. The teeth were randomly divided into 5 groups: group 1 (control un-demineralized) received no treatment, group 2 (control demineralized) had their surfaces demineralized after the IPR procedure, group 3 (fluoride) specimens were treated with fluoride gel (NUPRO, DENTSPLY, Charlotte, NC, USA) after the IPR, group 4 (Icon) resin infiltration material (Icon Proximal Mini Kit, DMG, Bielefeld, Germany) was applied after IPR, group 5 (MI varnish) specimens were treated with Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) containing varnish (MI Varnish, G.C, USA, St. Alsip, IL, USA) after the IPR. The specimens in (groups 2-5) were stored in a 4.5 pH demineralization solution for 4 days. The trans-micro-radiography (TMR) technique was conducted to evaluate the mineral loss (∆Z) and lesion depth of all specimens after the acid challenge. The obtained results were analyzed statistically using a one-way ANOVA at a significance level of α = 0.05. The MI varnish recorded significant ∆Z and lesion depth values compared to the other groups p > 0.05. There was no significant difference in ∆Z and lesion depth between the control demineralized, Icon, and fluoride groups p < 0.05. The MI varnish increased the enamel resistance to acidic attack, and thus can be considered an agent capable of protecting the proximal enamel surface after IPR.

Comparison of the temperature changes in pulp using monophasic light-emitting diode curing unit at different exposure times: An in vivo study

This invivo study evaluated the temperature changes in the pulp chamber at different exposure times using a monophasic light-emitting diode curing unit. Forty-five patients (aged 13-25 years) requiring extraction of maxillary first premolars for orthodontic reasons were included in the study. After access opening, the temperature rise was recorded when exposed to monophasic light-emitting diode curing light (Elipar 3M ESPE; Pymble, New South Wales, Australia) at 5, 10, 15, and 20 seconds with K-type thermocouple probe. Teeth were atraumatically extracted on the same day. The results were analyzed with an analysis of variance and the Bonferroni test. There was a significant increase of 2.1°C ± 0.5°C of pulpal temperature in the maxillary first premolar tooth during exposure to a light curing unit from baseline to 20 seconds. The mean baseline temperature was 35.7°C ± 0.52°C. The highest mean temperature was recorded at 20 seconds (37.8°C ± 0.57°C), and the lowest mean temperature was recorded at 5 seconds (36.1°C ± 0.61°C). There were significant differences among each group (P<0.001) with a mean increase in pulpal temperature from baseline to exposure mode of 5, 10, 15, and 20 seconds. The study results reveal a statistically significant increase in pulpal temperature with a monophasic curing light, which can be used for up to 20 seconds without causing any detrimental effects on the pulp.

Enamel Analysis by 3D Scanning after Three Orthodontic Clean-Up Procedures: An In-Vitro Test of a New Piezoelectric Tool.

(1) Background: To assess the clinical safety and efficacy of a new piezoelectric instrument for orthodontic clean-up; (2) Methods: An in-vitro comparative study on 75 teeth extracted for orthodontic reasons compared the tested method (Treatment 1) with two other procedures: One step finisher and polisher (Inverted cone One gloss Shofu Dental, Kyoto, Japan) (Treatment 2) and twelve-fluted tungsten carbide bur (123-603-00, Dentaurum, Pforzheim, Germany) and Sof-Lex discs Pop-On XT Kit (3M ESPE) (Treatment 3), with n:25 samples in each group. Clinical safety (enamel volume loss) and effectiveness (residual adhesive volume) were assessed using the structured light 3D scanner Atos Compact Scan (GOM GmbH) together with the support of Atos Professional software. The surfaces were scanned three times to assess: (i) the volume of the residual adhesive (RAV) after bracket removal; (ii) the volume of the relative residual adhesive (dAV) after the clean-up procedure; (iii) volume of the enamel loss (EVL); (3) Results: The mean RAV (mm3) was 0.239 ± 0.337; 0.069 ± 0.124, 0.120 ± 0.193 and the mean EVL (mm3) was 0.1870 ± 0.177, 0.187 ± 0.299 and 0.290 ± 0.205, for treatment 1, 2 and 3, respectively. The distribution was asymmetrical between groups in both cases; (4) Conclusions: The tested instrument proved to be effective and safe for post-orthodontic clean-up. With the increasing use of invisible aligners, the possibility of using an ergonomic and fast instrument is of benefit to both patient and practitioner.

The Influence of Chlorhexidine Gluconate Dentine Pre-Treatment on Adhesive Interface and Marginal Sealing.

Background and Objectives: The aim of this in vitro study was to evaluate the combined effect of a 2% chlorhexidine aqueous solution and a universal adhesive system applied in self-etch and etch-and-rinse strategies on the composite resin-dentin interface. Materials and Methods: Class V cavities were prepared on the facial and lingual surfaces of forty caries-free molars extracted for orthodontic reasons. The samples were randomly divided into two groups corresponding to the used etching protocol: I-etch-and-rinse; II-self-etch. In each tooth, one cavity was assigned for the control subgroups -IA (n = 20) and IIA (n = 20)-adhesive only, and the opposite cavity was pretreated with a 2% chlorhexidine solution-Gluco CHeX Cerkamed-subgroups IB (n = 20) and IIB (n = 20). Both sets of groups were restored using a universal adhesive system (Single Bond Universal Adhesive, 3M-ESPE) and a bulk-fill composite resin (Filtek One Bulk Fill Restorative, 3M-ESPE). The roots and the pulp tissue were then removed, and a needle connected to a perfusor with 100 mL saline solution was used for pulp pressure simulation with a hydrostatic pressure of 20 cm H2O. Cariogenic attack was simulated using a demineralizing solution for 3 days at a constant temperature of 25 °C. The teeth were then sectioned in a facial-lingual direction and the microleakages at the occlusal and cervical margins were registered and scored using an optical Carl-Zeiss AXIO Imager A1m microscope (Carl-Zeiss). The composite resin-dentin interface was analyzed using a SEM Vega Tescan LMH II. Statistical analysis was performed using the Kruskal-Wallis test with a significance level of p < 0.05. Results: Microleakage evaluation showed no significant differences among the study groups (p > 0.05). In subgroup IA, significant differences were recorded between occlusal and cervical margins (p < 0.05). Conclusions: Application of chlorhexidine on tooth substrate before using a universal bonding system in total etch or self-etch mode has no influence on the adhesive interface in the condition of cariogenic attack. The thickness of the adhesive resin layer seems to be less uniform when using chlorhexidine, but the morphological differences at the adhesive interface have no influence on the sealing capacity of the universal bonding system, regardless of the etching strategy.

The impact of irrigation procedures on the bond strength of fiber posts cemented with two different adhesive techniques

Introduction. Endodontically treated teeth are usually weaker due to the loss of tooth structure. As most of the crown of the tooth is destroyed, the most common retention for restoration is application of a fiber-reinforced composite posts in the root canal. In endodontically treated teeth, there are two main problems in the restorative procedure: reduced resistance of the remaining tooth structure and choosing the necessary adequate retention for restoration. The aim of this work was to evaluate the impact of irrigation protocol on the bond strength of two types of fiber posts luted with two different adhesive cements. Materials and method. In this in vitro study, 48 single-rooted teeth (incisors, single-rooted second premolars) extracted for orthodontic and periodontal reasons were used. The teeth were divided into the four groups of 12 teeth depending on the type of fiber post used as well as the irrigation agent. Each group was further divided into the two subgroups of six teeth depending on the material and cementation technique. Results. In all cross-sectional statistics the difference appeared only when different types of irrigants were used and they changed bond strength between dentin and bonding material. Conclusions. Irrigation protocol has a significant influence on the bond strength of composite post, independent of the type of post and cementation material used.

A cross-sectional study into the reasons behind orthodontic re-treatment.

This study aims to identify the motivations behind orthodontic re-treatment in Saudi Arabia. This is a cross-sectional study performed through a patient questionnaire. The questionnaire elicited data on the respondents' socio-demographic data, type of previous orthodontic treatment, retention, satisfaction level, and reasons for undergoing orthodontic re-treatment. Four hundred and nineteen responses were received during the study period from June to July 2022. The result showed a pre-dominant female predilection (83, 29%), with the majority belonging to the 21-25 age group (47.26%). Most participants had had one previous orthodontic treatment (77%), with an active treatment time of approximately 1-3 years (55.85%). There was no significant difference between the satisfaction of outcomes after the initial treatment and at the time of the survey. Most participants received retention appliances (69.45%) and were informed about the importance of appliances. The type of retention was mainly removable retainers (47.5%). Around one-third of the sample (31.98%) were interested in seeking orthodontic re-treatment, with self-motivation as the primary drive and improving the smile as the predominant reason. The study's findings show that a large portion of the population is seeking orthodontic re-treatment, which must be considered. Self-motivation was a driving force rather than external motivation. The most common reason for seeking orthodontic re-treatment was to improve their smile and the increased esthetic demand.