The importance of mechanosensitive cell mediated prostaglandin and nitric oxide synthesis in the pathogenesis of apical periodontitis: comparative with chronic periodontitis.

OBJECTIVES: Mechano-sensitive odontoblast cells, which sense mechanical loading and various stresses in the tooth structure, synthesize early signaling molecules such as prostaglandin E2 (PGE2) and nitric oxide (NO) as an adaptive response. It is thought that these synthesized molecules can be used for the diagnosis and treatment of periodontal and periapical diseases. The aim of this study was to investigate the relationship between the severity of apical periodontitis (AP) and chronic periodontitis (CP) and serum (s) TNF-α, IL-10, PGE2 and NO levels, as well as PGE2 and NO levels in gingival crevicular fluid (GCF) samples. MATERIALS & METHODS: A total of 185 subjects were divided into three categories: AP group (n = 85), CP group (n = 50) and healthy control group (n = 50). The AP group was divided into 3 subgroups according to abscess scoring (AS-PAI 1, 2 and 3) based on the periapical index. The CP group was divided into 4 subgroups according to the periodontitis staging system (PSS1, 2,3 and 4). After recording the demographic and clinical characteristics of all participants, serum (s) and gingival crevicular fluid (GCF) samples were taken. TNF-α, IL-10, PGE2 and NO levels were measured in these samples. RESULTS: Unlike serum measurements (sTNF-α, sIL-10, sNO and sPGE2), GCF-NO and GCF-PGE levels of the AP group were significantly higher than the control group in relation to abscess formation (54.4 ± 56.3 vs. 22.5 ± 12.6 µmol/mL, p < 0.001 and 100 ± 98 vs. 41 ± 28 ng/L, p < 0.001, respectively). Confirming this, the GCF-NO and GCF-PGE levels of the AS-PAI 1 group, in which abscesses have not yet formed, were found to be lower than those in AS-PAI 2 and 3, which are characterized by abscess formation [(16.7(3.7-117.8), 32.9(11.8-212.8) and 36.9(4.3-251.6) µmol/mL, p = 0,0131; 46.0(31.4-120.0), 69.6(40.3-424.2) and 74.4(32.1-471.0) ng/L, p = 0,0020, respectively]. Consistent with the increase in PSS, the levels of sTNF [29.8 (8.2-105.5) vs. 16.7(6.3-37.9) pg/mL, p < 0.001], sIL-10 [542(106-1326) vs. 190(69-411) pg/mL, p < 0.001], sNO [182.1(36.3-437) vs. 57.0(15.9-196) µmol/mL, p < 0.001], sPGE2 [344(82-1298) vs. 100(35-1178) ng/L, p < 0.001], GCF-NO [58.9 ± 33.6 vs. 22.5 ± 12.6 ng/L, p < 0.001] and GCF-PGE2 [ 99(37-365) vs. 30(13-119), p < 0.001] in the CP group were higher than the control group. Comparison ROC analysis revealed that the GCF-PGE2 test had the best diagnostic value for both AP and CP (sensitivity: 94.1 and 88.0; specificity: 64.0 and 78.0, respectively; p < 0.001). CONCLUSIONS: GCF-PE2 and GCF-NO have high diagnostic value in the determination of AP and CP, and can be selected as targets to guide treatment. In addition, the measurements of PGE2 and NO in GCF can be used as an important predictor of pulpal necrosis leading to abscess in patients with AP. CLINICAL RELEVANCE: In this article, it is reported that syntheses of early signaling molecules such as PGE2 and NO can be used for the diagnosis and treatment target of periapical and periodontal infections.

Relationships among barodontalgia prevalence, altitude, stress, dental care frequency, and barodontalgia awareness: a survey of Turkish pilots.

Background: Gas expansion in body cavities due to pressure changes at high altitudes can cause barodontalgia. This condition may compromise flight safety. Aim: To investigate relationships among barodontalgia awareness, dental visit frequency, and barodontalgia prevalence in civilian and military pilots operating at high altitudes. Materials and Methods: Civilian pilots from Turkish Airlines and military pilots from the Turkish Air Force, flying between November 2022 and January 2023, participated in this study. A 20-question survey was administered to 750 pilots, covering topics such as barodontalgia awareness, dental visit frequency, breaks after dental treatments, in-flight pain, and pain type and severity. The voluntary surveys were distributed by email. Results: Of the 750 pilots, 526 completed the survey; 61% were aware of barodontalgia, and 81% of pilots who had experienced it reported pain at altitudes <2000 feet. The study revealed higher barodontalgia awareness among pilots who had experienced it, with the highest prevalence among jet pilots. Pilots with barodontalgia also showed a higher frequency of dental visits (p < 0.001). Additionally, this group reported more frequent interruption of flight due to dental treatment (IFDT), more problems experienced in flights after treatment (PFAT), and higher instances of bruxism or teeth clenching during flight, suggesting stress and anxiety (p < 0.05). Conclusions: Barodontalgia, a type of pain linked to stress, significantly impacts pilot performance, and can threaten flight safety, even at lower altitudes. Thus, there is a need to educate pilots about stress management, barodontalgia awareness, and the importance of regular dental check-ups.

Relationship of MMP-9 with the clinical course of apical periodontitis and the main bacterial species in the oral microbiota.

Bacterial products, host immune cells and cytokines have been reported to play an important role in the pathogenesis of apical periodontitis (AP). This study aimed to determine the main bacterial species in the microbiota as gram positive and negative and to compare the relationship between matrix metalloproteinase (MMP)-9 and tumor necrosis factor (TNF)-α with controlled patient groups. 60 patients with AP and extraction indication were included in the study. 30 systemically healthy volunteers without AP were selected as the control group. After access cavity preparation, an initial microbiologic sample (S1) was taken from the root canal. After atraumatic extraction of the tooth, a second microbial sample (S2) was taken from the extraradicular region. After bacterial DNA extraction, 16S rRNA gene primer was designed for sequence analysis. Bacterial community profiling was made by Sanger sequencing of the PCR products. In addition, serum MMP-9 and TNF-α levels were measured from all patients. TNF-α levels of the AP group were higher than the control group, while MMP-9 levels were found to be lower (p = 0.0264 and p = 0.0146, respectively). There was no difference in the main bacterial species isolated from the samples taken from the intracanal and extraradicular region of the tooth with AP (p = 0.714). The main bacterial species in the intracanal region of the tooth with AP are similar to the main bacterial species in the extraradicular region. The pathophysiology of the tooth with AP is associated with low MMP-9 and high TNF-α, independent of the bacterial species in the intracanal and extraradicular regions.

Is XP-endo Finisher a better treatment option for its efficacy against intracanal bacteria for post-treatment apical periodontitis cases than EndoActivator?

To investigate the efficacy of the supplementary use of a rotary agitation method [XP-endo Finisher (XPF)] and sonically-activated irrigation [EndoActivator (EA)], using droplet digital PCR (ddPCR) on reducing the bacterial load in previously root canal treated teeth with apical periodontitis. Twenty patients with post-treatment apical periodontitis were allocated into two groups according to the irrigation activation method used: XPF and EA group. Total bacterial loads, as well as the amount of Enterococcus faecalis (E. faecalis) were determined before (S1) and after (S2) chemomechanical preparation, and after final irrigation activation (S3) by means of ddPCR. The bacterial copy numbers were compared between groups using the Friedman test (Nonparametric Repeated Measures ANOVA). When the groups were examined in terms of gender, age, number of root canals, periapical index score, sterility control total bacteria (SCTB), S1- and S2-total bacteria copy number, it was found that there was no statistical difference between the XPF group and the EA group (p > 0.05). Subsequent activation (S3) resulted in a significant microbial reduction in both XPF and EA groups, both of which reduced significantly more bacteria than chemomechanical instrumentation (S2) (p < 0.0001). On the contrary, S3-total bacteria copy number of the EA group was lower than the XPF group (p < 0.0147). There was no statistical difference between the XPF group and the EA group in terms of E. faecalis copy number (p > 0.05). Although both the XPF and the EA optimised the antibacterial efficiency of chemomechanical preparation in previously root canal-treated teeth with apical periodontitis, a lower total bacterial copy number was achieved with the EA application than the XPF application.

Microbial analysis of endodontic infections in teeth with post-treatment apical periodontitis before and after medication.

This study aimed to determine the intraradicular microbiota of previously root canal-treated teeth with apical periodontitis and to investigate the antibacterial effectiveness of different intracanal medicaments. Sixteen patients with post-treatment apical periodontitis were allocated into two groups according to the intracanal medicament used: calcium hydroxide (CH) and 2% chlorhexidine gluconate gel (CHX) group. Total bacterial loads, as well as the amount of Enterococcus faecalis (E. faecalis) were determined before (S1) and after (S2) chemomechanical preparation and finally, after intracanal medication (S3) by means of ddPCR. The unpaired t test was used to compare parametric. S3-total bacteria copy number of the CH group was lower than the CHX group (p < 0.05). There was no statistical difference between the CHX- and the CH groups in terms of E.faecalis copy number (p > 0.05). But in terms of total bacteria, CH is better than CHX. Consequently, CH can be used to optimise the antibacterial efficiency of chemomechanical preparation in previously root canal-treated teeth with apical periodontitis.

Is adrenomedullin upregulation due to apical periodontitis independent of periodontal disease?

To investigate the relationship between apical periodontitis [AP] severity and inflammatory markers [interleukin (IL)-12, tumor necrosis factor-alpha (TNF-α), and Mid-Regional Pro Adrenomedullin (MR-proADM)] in patients with AP. A total of 162 subjects were divided into three categories: AP group (n = 80), periodontitis (P) group (n = 42), healthy control group (n = 40). The scoring of disease severity in 80 AP patients without any periodontal disease, using dental radiographs, was based on "The Abscess Score" (AS), as those having at least 1 tooth with AP and severity of PAI 3-4 were classified as AS 1 (mild); those with only1 tooth and severity of PAI 5 as AS 2 (moderate) and those having > 2 tooth with severity of PAI 5 as AS 3 (severe). Blood samples were collected from all of the patients. Enzyme-linked immunosorbent assay was used to evaluate the samples. The MR-pro ADM levels of both the AP and P groups were considerably higher than the control group (p < 0.01). The IL-12 levels of the AP group were higher than the P and control groups (p < 0.05). TNF-α levels of the P group were significantly higher than both the AP and control groups (p < 0.01). MR-pro ADM levels of both the AP and Periodontitis groups were higher than the control group. TNF-α was a biomarker of periodontitis, while IL-12 was a biomarker of apical periodontitis.

Importance of Paired t-test in Time-based Comparison of Obturation and SealBio Techniques in Root Canal Treatment.

How to cite this article: Ozcelik F, Ersahan S. Importance of Paired t-test in Time-based Comparison of Obturation and SealBio Techniques in Root Canal Treatment. Int J Clin Pediatr Dent 2021;14(1):40.

The importance of inflammatory biomarkers, IL-6 and PAPP-A, in the evaluation of asymptomatic apical periodontitis.

To examine the use of IL-6 and PAPP-A along with the new imaging for scoring methods to determine the severity of apical periodontitis (AP). The scoring of disease severity in 121 patients with AP, using dental radiographs, was based on "The Apical Periodontitis Grading Scale" (APGS), as those having 1 tooth with AP and severity of 3-4 were classified as grade 1 (mild); those having > 1 tooth and severity of 3-4 as grade 2 (moderate) and those with at least one tooth with a severity of 5 as grade 3 (severe). 45 systematically and orally healthy volunteers were selected as the control group (grade 0). Dental demographic data of all participants were recorded. Besides, venous blood samples were collected to study their complete blood count and levels of IL-6 and PAPP-A. Both NLR and PAPP-A levels of the grade 3 AP patients were found significantly higher than those of the control group and grade 1 and grade 2 AP patients (2.55 ± 1.40 vs 1.98 ± 1.05, 1.94 ± 0.58 and 1.86 ± 0.50; 0.606 ± 0.211 vs 0.422 ± 0.273, 0.447 ± 0.224 and 0.436 ± 0.242, p < 0.01, respectively). AP grades identified by the new scoring system were moderately correlated with IL-6 levels (Spearman r = 0.4168, p < 0.001). The risk of patients with IL-6 levels above 12.5 pg/ml to develop AP (relative risk) was found to be 2.19 times higher than that in those with lower IL-6 levels (98% Cl 1.233-3.905, p < 0.0024). APGS classification suggested to determine AP severity was found to be significantly correlated with levels of inflammatory markers IL-6 and PAPP-A.

Impact of various finishing and polishing techniques and composite materials on Candida albicans biofilm formation.

Candida albicans biofilms are commonly associated with severe oral infections. In dentistry, prosthetic and restorative materials are potential structures for the adhesion of C. albicans facilitating the formation of Candida biofilm and infection. Three composite resins (Charisma Classic, Sonic Fill, Estelite ∑ Quick) and two finishing-polishing systems (Biscover LV, Dental Finishing Disc) were evaluated for Candida biofilm formation. A Candida biofilm assay showed that both the resin and the finishing/polishing procedures affect Candida biofilm formation. Specifically, Candida biofilm formation was significantly lower in Sonic Fill resin than both Charisma Classic and Estelite ∑ Quick (P = .021). The type of finishing and polishing procedure also significantly affected the Candida biofilm formation to composite material (P < .001). Candida biofilm formation was more advanced after Biscover LV procedure than Dental Finishing Disc procedure.

Comparison of the Effects of Various Methods Used to Remove Adhesive from Tooth Surfaces on Surface Roughness and Temperature Changes in the Pulp Chamber.

OBJECTIVE: The purpose of the present study was to compare the effects of three methods of removing adhesive on enamel surface roughness and dental pulp temperature. METHODS: Ninety human maxillary premolars were randomly divided into three groups (n=30) according to the type of adhesive clean-up procedure: aluminum oxide-based burs, erbium-doped yttrium aluminum garnet (Er:YAG) laser, and tungsten carbide bur. The surface roughness of enamel was measured using a non-contact optical profilometer. After the first readings of surface roughness were measured (T1), orthodontic brackets were attached to the enamel surface with composite. The brackets on the teeth were debonded using bracket removal pliers. The residue of adhesive was eliminated from the enamel surface of the teeth by different procedures in each group. While removing adhesive from the tooth surface, the intrapulpal temperature rise was simultaneously measured using a thermocouple. One-way ANOVA and post-hoc Tukey HSD tests were used to analyze data with a significance level set at 0.05. RESULTS: The highest roughness average (Ra) values were observed for the Er:YAG laser group, with a significant difference with the aluminum oxide bur group and tungsten carbide bur group (p<0.001). Ra values for the aluminum oxide bur group were significantly lower than those for the other groups (p<0.001). Comparing the thermal changes in each group showed a significant decrease in the Er:YAG laser group, but a significant increase in two other groups. CONCLUSION: Within the limitations of the present study, one-step finisher and polisher bur created the smoothest enamel surface, whereas Er:YAG laser the roughest. Tungsten carbide and aluminum oxide-based burs generated more heat than Er:YAG laser.

Comparison of the Effects of Two Different Analgesics on Bone Regeneration During Mandibular Distraction Osteogenesis.

INTRODUCTION: Mandibular distraction osteogenesis (DO) is frequently used in the management of bone defects and craniofacial deformities, with analgesics commonly administered to relieve acute postoperative pain. This experimental animal study investigated the effects of 2 analgesics, acetaminophen and acemetacin, on bone regeneration after DO. MATERIALS AND METHODS: This study was conducted with 14 mature male New Zealand rabbits (2.8-3.2 kg) randomized into 2 groups of 7. Mandibular osteotomies were performed under optimal operating conditions, and a custom-made distractor was applied to the mandible of each subject, with distraction initiated after a 5-day latency period at a rate of 1.0 mm/d (2 × 0.5 mm/d) for 10 days. Analgesics were administered via oral gavage during the latency period and for the first 5 days of the distraction period for 10 days in total, with group I receiving acetaminophen (200 mg/kg/d) and group II receiving acemetacin (5 mg/kg/d). Subjects were sacrificed and their mandibles dissected at the end of 4 weeks postoperatively. Bone mineral density (BMD) and bone mineral content (BMC) were measured using dual-energy X-ray absorptiometry (DEXA), and histomorphometric analysis was performed to evaluate the quality of newly formed bone. Paired group comparisons of non-normally distributed numerical variables were made using the Mann-Whitney U test, with a P value of <0.05 considered statistically significant. RESULTS: No significant differences in BMC and BMD values of intact bone, newly formed bone, or bone around the pin site were observed between the 2 groups. Histometric analysis also indicated acetaminophen and acemetacin to have similar effects on bone regeneration during distraction. CONCLUSION: Acemetacin may be an alternative to acetaminophen for treating pain associated with DO, given the similarities in the effects of the 2 analgesics on bone regeneration. However, this finding should be supported by further experimental and human studies.

Effect of age on pulpal blood flow in human teeth during orthodontic movement.

We aimed to assess the relationship between age, pulpal blood flow (PBF), and orthodontic treatment outcomes. Decreased blood supply to pulp cells commonly occurs with age and can change the response of pulp to orthodontic tooth movement. This study was conducted in 28 human subjects divided into 2 groups according to age. A laser Doppler flowmeter was used to record blood flow to the teeth prior to and during the course of orthodontic treatment (days 1, 3, and 7; week 3; and month 1). Data were analyzed using Wilcoxon signed-rank and Mann-Whitney U tests. Mean PBF values were significantly higher in the young group compared to the old group at all time points (P < 0.001). The decreased PBF in response to tooth movement was more severe in the old group and was also of longer duration. Pulp in younger patients had significantly higher blood flow values compared to that in older patients at baseline and throughout the course of the study.

The Efficacy of Laser Doppler Flowmetry, Electric Pulp Test and Cold Test in Diagnosing Revascularization of Extrusively Luxated Immature Maxillary Incisors.

OBJECTIVE: To evaluate the effect of extrusion on immature permanent tooth PBF values during a 6-month post-trauma period and to compare the accuracy of cold tests on pulp sensibility of traumatized teeth with that of electric pulp tests (EPT). METHODS: The study group comprised of 26 extruded immature maxillary incisors in 25 trauma patients. The respective contralateral homologous teeth (n=25) were included as a positive control group. Teeth in the study group were treated by repositioning and splinting. Pulp vitality readings for traumatized and control teeth were taken with LDF, EPT and cold test on the day of splint-removal (2-3 weeks after trauma-T1) as well as 6 weeks (T2), 3 months (T3) and 6 months (T4) post-trauma. Student t and Mann-Whitney U-tests were used to compare data among groups. Statistical significance was set at P< 0.05. RESULTS: LDF gave positive vitality readings (>4.5 PU) in all patients from T1 to T4 (with the exception of 1 patient at T1). CONCLUSIONS: LDF was able to accurately identify vitality in traumatized immature teeth even during the first few weeks following trauma, whereas conventional sensibility tests were unable to accurately recognize vitality shortly after trauma.

Effect of intracanal medicaments used in endodontic regeneration on the push-out bond strength of a calcium-phosphate-silicate-based cement to dentin.

OBJECTIVE: To evaluate the effects of various endodontic regeneration agents on the push-out bond strength of Endosequence Root Repair Material (ERRM) to root-canal dentin. METHODS: Fifty single-rooted human teeth were selected and instrumented to obtain a standard internal diameter of 1.5 mm. Specimens were randomly divided into four experimental groups and treated with an intracanal medicament [calcium hydroxide (CH), double antibiotic paste (DAP), triple antibiotic paste (TAP), TAP with amoxicillin (mTAP)] and a non-treated control group. Medicaments were removed after three weeks, and ERRM was applied to all specimens. The coronal portion of each root was then sliced into 2-mm-thick parallel transverse sections (2 slices per tooth, n=20 slices per group), and a push-out test was used to measure the bond strength of ERRM to dentin. Data were analyzed using Bonferroni-corrected Mann-Whitney tests, with the level of significance set at p<0.05. RESULTS: The push-out bond strength of the CH group was significantly higher than that of the TAP, DAP and mTAP groups (p< 0.005). Furthermore, the bond strength of the control group was higher than the bond strength of both the DAP and mTAP groups. CONCLUSION: The use of CH in clinical practice may help improve the adhesion of ERRM to dentin.

Comparison of Four Electronic Apex Locators in Detecting Working Length: An Ex Vivo Study.

AIM: To compare the accuracy of four different electronic apex locators (EALs) in detecting a position 0.5 mm short of the major foramen. MATERIALS AND METHODS: The actual working length of thirty-five extracted human teeth was determined visually as 0.5 mm short of the apical foramen. After actual working length measurements, electronic working length was measured with four different EALs (Apex Pointer+, Raypex 5, Apex ID, and Raypex 6). Measurements were repeated three times by different operators. The data were analyzed using the intraclass correlation coefficient (ICC), the repeated measure analysis of variance (rANOVA) and Bonferroni post hoc tests. The significance level was set at p < 0.05. RESULTS: The mean differences between electronic and actual working length were-0.305 mm, 0.098 mm, 0.037, and 0.144 mm for the Apex Pointer+, the Raypex 5, the Apex ID, and the Raypex 6, respectively. Multiple paired comparisons (Bonferroni test) also showed the Apex Pointer+ is significantly different from the Raypex 5, Apex ID and Raypex 6 (p = 0.000, p = 0.001, and p = 0.001 respectively). CONCLUSION: All EALs showed an acceptable determination of the working length between the ranges of ± 0.5mm except for the Apex Pointer+ device, which had the lowest accuracy. Further studies may be beneficial especially to better evaluate the accuracy of the Apex Pointer+. CLINICAL SIGNIFICANCE: This article shows that Apex ID, which has only recently been introduced into the market, showed an acceptable determination of the working length. Its accuracy was similar to that of Raypex 5 and 6.

Changes in human pulp blood flow during canine retraction.

AIM: To evaluate the effects of maxillary canine retraction on pulpal blood flow (PBF) in humans as recorded by laser Doppler flowmetry (LDF). METHODS: Maxillary canines of 24 participants were divided into two groups (n = 12 each). Teeth in the study group underwent maxillary canine retraction using mini-implants as anchorage for approximately 4 months, with 100 g of force applied via coil springs. Subjects in the control group received no orthodontic treatment. LDF measurements were recorded at baseline (T0); during retraction, at 24 hours (T1), 3 days (T2), 7 days (T3) and 1 month (T4); and at the end of retraction (T5) in the study group and at similar time-points in control subjects. Data were analyzed using the Friedman, Wilcoxon signed rank and Mann-Whitney U tests, with the significance level set at 0.05. RESULTS: No significant changes in PBF perfusion units (PU) were observed in the control group over the course of the study. However, PBF in the study group increased significantly from T0 (3.6 ± 0.2 PU) to T1 (3.7 ± 0.2 PU, p < 0.001) and decreased severely from T1 to T2 (3.3 ± 0.1, p < 0.001). PBF in the study group was still significantly lower at T3 (3.4 ± 0.1 PU, p < 0.001) in comparison to T0; however, at T4 and T5, PBF was found to have returned to pre-retraction levels. CONCLUSION: The fact that PBF values returned to initial levels within one month of the initiation of retraction despite short-term, hyperaemic, regressive changes demonstrates that the changes observed in PBF during canine retraction are reversible.

Changes in Maxillary Canine Pulpal Blood Flow During Dentoalveolar Distraction Osteogenesis.

OBJECTIVE: The aim of this study was to assess the effects of dentoalveolar distraction osteogenesis (DD) on the pulpal blood flow (PBF) of maxillary canines. MATERIALS AND METHODS: A laser Doppler flowmeter (LDF) was used to measure PBF in maxillary canines of 10 patients undergoing DD (study group) and 10 nonsurgical subjects who received no orthodontic treatment (control group). PBF was measured at baseline, at 4 and 7 days postoperatively, at the end of distraction and at the end of consolidation in the study group and at similar time-points in nonsurgical control subjects. Data were analyzed using paired and Student t tests, with the significance level set at 0.05. RESULTS: Study findings showed that baseline PBF values did not differ significantly between groups. PBF in the control group did not vary over time; however, in the study group, an initial decrease in PBF was observed at 4 days postoperatively and was followed by a gradual increase to preoperative levels at the end of distraction. CONCLUSIONS: During the DD latency period, there appears to be a short-lived ischemic phase when perfusion of pulp tissue declines; however, blood-flow returns to normal by the end of distraction.

Effect of surface treatment on enamel surface roughness.

PURPOSE: To compare the effects of different methods of surface treatment on enamel roughness. MATERIALS AND METHODS: Ninety human maxillary first premolars were randomly divided into three groups (n=30) according to type of enamel surface treatment: I, acid etching; II, Er:YAG laser; III, Nd:YAG laser. The surface roughness of enamel was measured with a noncontact optical profilometer. For each enamel sample, two readings were taken across the sample-before enamel surface treatment (T1) and after enamel surface treatment (T2). The roughness parameter analyzed was the average roughness (Ra). Statistical analysis was performed using a Paired sample t test and the post-hoc Mann- Whitney U test, with the significance level set at 0.05. RESULTS: The highest Ra (average roughness) values were observed for Group II, with a significant difference with Groups I and III (P<0.001). Ra values for the acid etching group (Group I) were significantly lower than other groups (P<0.001). CONCLUSION: Surface treatment of enamel with Er:YAG laser and Nd:YAG laser results in significantly higher Ra than acid-etching. Both Er:YAG laser or Nd:YAG laser can be recommended as viable treatment alternatives to acid etching.

Debonding of ceramic brackets by Er:YAG laser.

PURPOSE: The objective of the present study is to evaluate the effects of Er:YAG laser debonding of ceramic brackets on the bond strength and the amount of adhesive resin remnant. MATERIALS AND METHODS: Twenty human mandibular incisors were randomly divided into two groups of 10 and polycrystalline ceramic brackets (Transcend series 6000, 3M Unitek, Monrovia, CA, USA) were bonded on enamel surfaces. Group 1 was the control group in which no laser application was performed prior to the shear bond strength (SBS) testing. In Group 2, Er:YAG was applied in 3W power for 6 seconds using the scanning method. The brackets were tested for SBS with an Instron universal testing machine and results were expressed in megapascals (MPa). The amount of adhesive remnant was evaluated with Adhesive Remnant Index (ARI). One-way analysis of variance and Tukey's post-hoc tests were used for statistical analysis. RESULTS: Mean ± standard deviation of SBS values in the control group was 13.42 ±1.23 MPa and 8.47 ±0.71 MPa in the Er:YAG group and this difference was statistically significant (p<0.05). The evaluation of ARI scores demonstrated more adhesive was left on the enamel surface with Er:YAG group. CONCLUSION: 3W power Er:YAG laser application with the scanning method to polycrystalline ceramic brackets demonstrated lower bond strengths and higher ARI scores during the debonding procedure.