Influence of augmented reality technique on the accuracy of autotransplanted teeth in surgically created sockets.

BACKGROUND: The objective of the present study was to evaluate the reliability of an augmented reality drilling approach and a freehand drilling technique for the autotransplantation of single-rooted teeth. MATERIALS AND METHODS: Forty samples were assigned to the following surgical techniques for drilling guidance of the artificial sockets: A. augmented reality technique (AR) (n = 20) and B. conventional free-hand technique (FT) (n = 20). Then, two models with 10 teeth each were submitted to a preoperative cone-beam computed tomography (CBCT) scan and a digital impression by a 3D intraoral scan. Afterwards, the autotrasplanted teeth were planned in a 3D dental implant planning software and transferred to the augmented reality device. Then, a postoperative CBCT scan was performed. Data sets from postoperative CBCT scans were aligned to the planning in the 3D implant planning software to analize the coronal, apical and angular deviations. Student's t-test and Mann-Whitney non-parametric statistical analysis were used to analyze the results. RESULTS: No statistically significant differences were shown at coronal (p = 0.123) and angular (p = 0.340) level; however, apical deviations between AR and FT study groups (p = 0.008) were statistically significant different. CONCLUSION: The augmented reality appliance provides higher accuracy in the positioning of single-root autotransplanted teeth compared to the conventional free-hand technique.

Is Revascularization the Treatment of Choice for Traumatized Necrotic Immature Teeth? A Systematic Review and Meta-Analysis.

Regenerative endodontic treatment (RET) has been considered a reliable procedure to treat immature necrotic teeth; however, the effect of dental trauma on the prognosis of RET is questionable. This systematic review aimed to evaluate the current level of evidence for revascularization techniques (the RET) in the management of traumatized necrotic immature permanent teeth with or without periapical radiolucent areas. Four electronic databases-PubMed, Web of Science, Scopus, and Embase-were searched until November 2022. Only randomized clinical trials, cohort studies, and case-control studies with a minimum of 10 cases and 12 months of follow-ups were included. The search identified 363 preliminary results. After discarding the duplicates and screening the titles, abstracts, and full texts, 13 articles were considered eligible. The results showed that RET techniques seemed to have high survival and success rates, 93.8% and 88.3%, respectively, in the treatment of traumatized necrotic immature permanent teeth. Root maturation with RET techniques seemed to be lower in traumatized teeth. Future studies are needed to evaluate root maturation in traumatized teeth using 3-dimensional radiographic evaluations. In addition, the lack of literature on the studies comparing RET and apexification (calcium hydroxide or an MTA) in the treatment of traumatized necrotic immature teeth highlights the necessity for high-level clinical studies comparing these treatment modalities.

Analysis of the Frequency and Correlated Factors of Midpalatal Suture Maturation Stages in Young Adults, Based on Cone Beam Computed Tomography Imaging.

BACKGROUND: The choice of whether to perform a palatal disjunction in constricted maxilla has traditionally been decided based on the age of the patients, although there are gradually increasing references to the fact that this is not a determining factor. The main goal of this study was to evaluate the frequency of the different stages of midpalatal suture maturation in a sample of young adults between 15 and 30 years of age. Other objectives also included analyzing the possible correlation the maturation stages could maintain with sex and age groups. METHODS: 142 Cone Beam Computed Tomography (CBCT) scans of young adults were performed. The images were divided into four age groups based on age ranges of 15-18, 19-22, 23-26, and 27-30 years. Each group consisted of 26, 41, 39, and 36 patients, respectively, which were classified using Angelieri's method. In addition, sex and age groups were considered as variables, and the possible correlation of the prevalence of each one, according to age and sex, was studied. RESULTS: the sample was classified into 4.9% stage B; 52.1% stage C; 27.5% stage D; and 15.5% stage E. In addition, no statistically significant correlation between sex and the maturation stages was found, but more advanced stages did appear to be related to the chronological age of the subjects. CONCLUSIONS: The frequency of maturational stages where the suture is shown to be consolidated did not appear to be as high as expected; therefore, the idea of rejecting transverse plane treatment in a conventional manner in an out-of-growth patient should be discarded.

Accuracy of Endodontic Access Cavities Performed Using an Augmented Reality Appliance: An In Vitro Study.

INTRODUCTION: The purpose of this study was to compare and contrast the accuracy of endodontic access cavities created using an augmented reality appliance to those performed using the conventional technique. MATERIALS AND METHODS: 60 single-rooted anterior teeth were chosen for study and randomly divided between two study groups: Group A-endodontic access cavities created using an augmented reality appliance as a guide (n = 30) (AR); and Group B-endodontic access cavities performed with the manual (freehand) technique (n = 30) (MN). A 3D implant planning software was used to plan the endodontic access cavities for the AR group, with a cone-beam computed tomography (CBCT) and 3D intraoral surface scan taken preoperatively and subsequently transferred to the augmented reality device. A second CBCT scan was taken after performing the endodontic access cavities to compare the planned and performed endodontic access for accuracy. Therapeutic planning software and Student's t-test were used to analyze the cavities at the apical, coronal, and angular levels. The repeatability and reproducibility of the digital measurement technique were analyzed using Gage R&R statistical analysis. RESULTS: The paired t-test found statistically significant differences between the study groups at the coronal (p = 0.0029) and apical (p = 0.0063) levels; no statistically significant differences were found between the AR and MN groups at the angular (p = 0.6596) level. CONCLUSIONS: Augmented reality devices enable the safer and more accurate performance of endodontic access cavities when compared with the conventional freehand technique.

Effect of Rotational Speed on the Resistance of NiTi Alloy Endodontic Rotary Files to Cyclic Fatigue-An In Vitro Study.

The present study aims to evaluate and contrast the function of the rotational speed of NiTi alloy endodontic rotary files on how resistant they are to dynamic cyclic fatigue. Methods: A total of 150 NiTi alloy endodontic rotary files with similar geometrical design and metallurgical properties were randomly divided into study groups: Group A: 200 rpm (n = 30); Group B: 350 rpm (n = 30); Group C: 500 rpm (n = 30); Group D: reciprocating movement at 350 rpm with 120° counterclockwise and 30° clockwise motion (350 rpm+) (n = 30); and Group E: reciprocating movement at 400 rpm with 120° counterclockwise and 30° clockwise motion (400 rpm+) (n = 30). A dynamic device was designed to carry out dynamic cyclic fatigue tests using artificial root canal systems made from stainless steel with an apical diameter of 250 µm, 5 mm radius of curvature, 60° curvature angle, and 6% taper, and 20 mm in length. A Weibull statistical analysis and ANOVA test were used to analyze the results. Results: The ANOVA analysis showed differences in time to failure among all the study groups that were of statistical significance (p < 0.001). Conclusions: NiTi alloy endodontic rotary files using reciprocating movement at 350 rpm with 120° counterclockwise and 30° clockwise motion exhibit greater resistance to dynamic cyclic fatigue than files used with a reciprocating movement at 400 rpm with 120° counterclockwise and 30° clockwise motion, continuous rotational speed at 200 rpm, continuous rotational speed at 350 rpm, or continuous rotational speed at 500 rpm; it is therefore advisable to use reciprocating movements at a low speed.

Comparative Study of the SEM Evaluation, EDX Assessment, Morphometric Analysis, and Cyclic Fatigue Resistance of Three Novel Brands of NiTi Alloy Endodontic Files.

In this study, we compare and analyze the scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), morphometry and cyclic fatigue resistance of Endogal, PathMax, and Smarttrack novel brands of nickel−titanium (NiTi) alloy endodontic files. Material and Methods: Thirty sterile NiTi endodontic rotary files were randomly selected and assigned to one of the following study groups: A: 25.08 F2 Endogal (EDG) (n = 10); B: 25.08 F2 Path Max Pro (PMP) (n = 10); and C: 25.06 Smarttrack (ST) (n = 10). Dynamic cyclic fatigue tests were conducted using a cyclic fatigue device in stainless steel artificial root canal systems with an apical diameter of 250 µm, curvature angle of 60°, radius of curvature of 3 mm, and taper of 6%. Additionally, we analyzed the NiTi endodontic rotary files using EDX, SEM, and morphometry after micro-CT scanning. The results were analyzed using Weibull statistical analysis and ANOVA testing. Results: SEM, EDX, and morphometric analyses showed differences between the three novel brands of NiTi endodontic rotary files. Moreover, statistically significant differences were observed between the number of cycles to failure and time to failure of the three novel brands of NiTi endodontic rotary files (p < 0.001). Conclusions: Smarttrack NiTi alloy endodontic reciprocating files display greater resistance to cyclic fatigue than Endogal and Path Max Pro NiTi alloy endodontic rotary files, due to the reciprocating movement and metallurgical composition.

A Novel Digital Technique to Analyze the Wear of CM-Wire NiTi Alloy Endodontic Reciprocating Files: An In Vitro Study.

The present study seeks to describe a novel digital measurement technique for analyzing the wear volume of controlled memory (CM)-wire NiTi alloy endodontic reciprocating files after clinical use. MATERIAL AND METHODS: Ten CM-wire NiTi endodontic reciprocating files were randomly used in ten first upper molar teeth within four root canals. The CM-wire NiTi alloy endodontic reciprocating files were subjected to preoperative and postoperative micro-computed tomography (micro-CT) scans to obtain accurate digital imaging and communication on medicine (DICOM) digital files, which were segmented using intensity-based thresholding and an exclusive OR (XOR) logical operation (Boolean algebra logical operator) to obtain a mask of the location to localize and quantify the wear volume of the CM-wire NiTi alloy endodontic reciprocating files. Gage repeatability and reproducibility statistical analysis was applied to assess the reproducibility and repeatability of this measurement technique. RESULTS: The analysis showed a repeatability and reproducibility of 0.00% for the digital measurement technique used to analyze the wear volume of CM-wire NiTi alloy endodontic reciprocating files after clinical use. Wear was mostly identified at the tip and cutting edges of the CM-wire NiTi alloy endodontic reciprocating files. CONCLUSIONS: This novel digital measurement technique is a repeatable, reproducible, and accurate method of quantifying the wear volume of CM-wire NiTi alloy endodontic reciprocating files after clinical use.

Comparative Analysis of Root Canal Dentin Removal Capacity of Two NiTi Endodontic Reciprocating Systems for the Root Canal Treatment of Primary Molar Teeth. An In Vitro Study.

The objective of the present study was to evaluate and compare the dentin removal capacity of Endogal Kids and Reciproc Blue NiTi alloy endodontic reciprocating systems for root canal treatments in primary second molar teeth via a micro-computed tomography (micro-CT) scan. MATERIALS AND METHODS: Sixty root canal systems in fifteen primary second molar teeth were chosen and classified into one of the following study groups: A: EK3 Endogal Kids (n = 30) (EDG) and B. R25 Reciproc Blue (n = 30) (RB). Preoperative and postoperative micro-CT scans were uploaded into image processing software to analyze the changes in the volume of root canal dentin using a mathematical algorithm that enabled progressive differentiation between neighboring pixels after defining and segmenting the root canal systems in both micro-CT scans. Volumetric variations in the root canal system and the root canal third were calculated using a t-test for independent samples or a nonparametric Mann-Whitney-Wilcoxon test. RESULTS: Statistically significant differences (p = 0.0066) in dentin removal capacity were found between the EDG (2.89 ± 1.26 mm3) and RB (1.22 ± 0.58 mm3) study groups for the coronal root canal third; however, no statistically significant differences were found for the middle (p = 0.4864) and apical (p = 0.6276) root canal thirds. CONCLUSIONS: Endogal and Reciproc Blue NiTi endodontic reciprocating systems showed similar capacity for the removal of root canal dentin, except for the coronal root canal third, in which the Reciproc Blue NiTi endodontic reciprocating system preserved more root canal dentin tissue.

Comparative Analysis of Ease of Removal of Fractured NiTi Endodontic Rotary Files from the Root Canal System-An In Vitro Study.

This study aimed at analyzing and comparing the ease of removal of fractured nickel-titanium (NiTi) endodontic rotary files from the root canal system between the ultrasonic tips and the Endo Rescue appliance removal systems, as well as comparing the volume of dentin removed between ultrasonic tips and the Endo Rescue appliance using a micro-computed tomography (micro-CT) scan. MATERIAL AND METHODS: Forty NiTi endodontic rotary files were intentionally fractured in 40 root canal systems of 20 lower first molar teeth and distributed into the following study groups: A: Ultrasonic tips (n = 20) (US) and B: Endo Rescue device (n = 20) (ER). Preoperative and postoperative micro-CT scans were uploaded into image processing software to analyze the volumetric variations of dentin using an algorithm that enables progressive differentiation between neighboring pixels after defining and segmenting the fractured NiTi endodontic rotary files and the root canal systems in both micro-CT scans. A non-parametric Mann-Whitney-Wilcoxon test or t-test for independent samples was used to analyze the results. RESULTS: The US and ES study groups saw 8 (1 mesiobuccal and 7 distal root canal system) and 3 (distal root canal system) fractured NiTi endodontic rotary files removed, respectively. No statistically significant differences were found in the amount of dentin removed between the US and ER study groups at the mesiobuccal (p = 0.9109) and distal root canal system (p = 0.8669). CONCLUSIONS: Ultrasonic tips enable greater ease of removal of NiTi endodontic rotary files from the root canal system, with similar amounts of dentin removal between the two methods.

Influence of the Geometrical Cross-Section Design on the Dynamic Cyclic Fatigue Resistance of NiTi Endodontic Rotary Files-An In Vitro Study.

The aim of this study was to analyze and compare the influence of the geometrical cross-section design on the dynamic cyclic fatigue resistance of NiTi endodontic rotary files. MATERIALS AND METHODS: Forty sterile endodontic rotary files were selected and distributed into the following study groups: A: 25.06 double S-shaped cross-section NiTi alloy endodontic rotary files (Mtwo) (n = 10); B: 20.04 rectangular cross-section NiTi alloy endodontic rotary files (T Pro E1) (n = 10); C: 25.04 convex triangular cross-section NiTi alloy endodontic rotary files (T Pro E2) (n = 10); and D: 25.06 triangular cross-section NiTi alloy endodontic rotary files (T Pro E4) (n = 10). A cyclic fatigue device was used to conduct the static cyclic fatigue tests with stainless steel artificial root canal systems with 200 µm and 250 µm apical diameter, 60° curvature angle, 3 mm radius of curvature, 20 mm length, and 4% and 8% taper. The results were analyzed using the ANOVA test and Weibull statistical analysis. RESULTS: All the pairwise comparisons presented statistically significant differences between the time to failure and number of cycles to failure for the cross-section design study groups (p < 0.001). CONCLUSIONS: the double S-shaped cross-section of Mtwo NiTi endodontic files shows higher cyclic fatigue resistance than the rectangular cross-section of T Pro E1 NiTi endodontic files, the convex triangular cross-section of T Pro E2 NiTi endodontic files, and the triangular cross-section of T Pro E4 NiTi endodontic files.

A Novel Digital Technique for Measuring the Accuracy of an Indirect Bonding Technique Using Fixed Buccal Multibracket Appliances.

The aim of this study was to analyze the accuracy and predictability of the indirect bonding technique of fixed buccal multibracket appliances using a customized iterative closest point algorithm. MATERIALS AND METHODS: A total of 340 fixed buccal multibracket appliances were virtually planned and bonded on 34 experimental anatomically based acrylic resin models by using orthodontic templates designed and manufactured to indirectly bond the fixed buccal multibracket appliances. Afterwards, the models were submitted to a three-dimensional impression technique by an intraoral scanner, and the standard tessellation language digital files from the virtual planning and the digital impression were aligned, segmented, and realigned using morphometric software. Linear positioning deviations (mm) of the fixed buccal multibracket appliances were quantified at mesio-distal, bucco-lingual/palatal, and gingival/occlusal (vertical) planes, and angular deviations (°) were also recorded by analyzing the torque, tip, and rotation using a customized iterative closest point algorithm, the script for which allowed for an accuracy measurement procedure by comparing the tessellation network positioning of both standard tessellation language digital files. RESULTS: The mean mesio-distal deviation was -0.065 ± 0.081 mm, the mean bucco-lingual/palatal deviation was 0.129 ± 0.06 m, the mean vertical deviation was -0.094 ± 0.147 mm, the mean torque deviation was -0.826 ± 1.721°, the mean tip deviation was -0.271 ± 0.920°, and the mean rotation deviation was -0.707 ± 0.648°. CONCLUSION: The indirect bonding technique provides accurate and predictable positioning of fixed buccal multibracket appliances.

Efficacy of Removing Thermafil and GuttaCore from Straight Root Canal Systems Using a Novel Non-Surgical Root Canal Re-Treatment System: A Micro-Computed Tomography Analysis.

The present study aims to evaluate the effectiveness of an XP-endo non-surgical root canal re-treatment system in removing both GuttaCore and Thermafil gutta-percha carrier-based root canal filling materials from straight root canal systems using micro-computed tomography (micro-CT) analysis. The study was performed on 20 single-rooted upper teeth, which were randomly allocated into the following study groups: Group A, Thermafil and AH Plus sealer (n = 10); Group B, GuttaCore and AH Plus sealer (n = 10). Before and after the non-surgical root canal re-treatment procedure, the samples were submitted for a micro-CT analysis. The volume of the root canal filling material (mm3), the volume of the remaining root canal filling material (mm3) and the time (minutes) needed to remove the root canal filling material were also recorded. Student's t-test was used to analyze the results. No statistically significant differences were found between the volume of the remaining root canal filling material in the GuttaCore and Thermafil root canal filling systems at the coronal third (p = 0.782), middle third (p = 0.838) or apical third (p = 0.882) of the straight root canal systems; however, the GuttaCore required a statistically significant (p = 0.037) shorter amount of time (4.72 ± 0.76 min) to be removed than the Thermafil carrier-based root canal filling material (5.92 ± 1.42 min). The XP-endo Finisher non-surgical endodontic re-treatment system removes both GuttaCore and Thermafil gutta-percha carrier-based root canal filling materials from straight root canal systems, although removal of the GuttaCore gutta-percha carrier-based root canal filling material required less time.

The Influence of NiTi Alloy on the Cyclic Fatigue Resistance of Endodontic Files.

BACKGROUND: The aim of this study was to analyze the influence of NiTi alloy in endodontic rotary instruments on cyclic fatigue resistance. METHODS: One hundred and sixty-four (164) sterile endodontic rotary files were selected and distributed into the following study groups: A: 25.08 F2 ProTaper Universal (PTU) (n = 41); B: 25.06 X2 ProTaper Next (PTN) (n = 41); C: 25.08 F2 ProTaper Gold (PTG) (n = 41), and D: 25.06 ProFile Vortex Blue (PVB) (n = 41). A cyclic fatigue device was designed to conduct the static cyclic fatigue tests with stainless steel artificial root canals systems with 250 µm apical diameter, 60° curvature angle, 5 mm radius of curvature, 20 mm length, and 6% (25.06) and 8% taper (25.08). Failure of the endodontic rotary instrument was detected by a single operator through direct observation and was also filmed to allow measurement of the exact time to failure. Results were analyzed using the ANOVA test and Weibull statistical analysis. RESULTS: All pairwise comparisons presented statistically significant differences between the time to failure for the NiTi alloy study groups (p < 0.001), except between the PTN and PVB study groups (p = 0.379). In addition, statistically significant differences between the number of cycles to failure for the NiTi alloy study groups (p < 0.001) were also observed. CONCLUSIONS: The NiTi CM-Gold wire alloy of the ProTaper Gold endodontic rotary files resulted in greater resistance to cyclic fatigue than ProFile Vortex Blue, ProTaper Next, and ProTaper Universal endodontic rotary files.

The Efficacy of Rotary, Reciprocating, and Combined Non-Surgical Endodontic Retreatment Techniques in Removing a Carrier-Based Root Canal Filling Material from Straight Root Canal Systems: A Micro-Computed Tomography Analysis.

The aim of this study is to analyze and compare the efficacy of three non-surgical endodontic retreatment techniques in removing a carrier-based root canal filling material from straight root canal systems. The study was performed on 99 single-rooted extracted teeth using the ProTaper Gold endodontic rotary system up to the F2 file (Dentsply Maillefer, Baillagues, Switzerland), which were sealed with GuttaCore (Dentsply Maillefer, Ballaigues, Switzerland) and AH plus epoxy resin sealer (Dentsply DeTrey, Konstanz, Germany) and randomly assigned to the following non-surgical retreatment techniques: ProTaper Retreatment endodontic rotary instruments (D1-D3 files, Dentsply Maillefer, Ballaigues, Switzerland; n = 33, PTR), Reciproc Blue endodontic reciprocating instrument (R50, VDW, Munich, Germany; n = 33, RCB50), and a combined root canal retreatment technique between Gates-Glidden drills (sizes #3 and #2, Dentsply Maillefer, Ballaigues, Switzerland) and Hedstrom files (file size 35, 30, and 25, Dentsply Maillefer, Ballaigues, Switzerland; n = 33; H-GG). All of the teeth were submitted twice to a micro-computed tomography (micro-CT) scan, before and after non-surgical endodontic retreatment procedures. The volume of root canal filling material (mm3), volume of remaining root canal filling material (mm3), non-surgical endodontic retreatment working time (min), proportion of remaining root canal filling material (%), and efficacy of root canal filling material removal between the non-surgical endodontic retreatment techniques were analyzed using ANOVA one-way statistical analysis. Statistically significant differences were observed between the proportions of remaining root canal filling material of PTR and H-GG (p = 0.018), between the non-surgical endodontic retreatment working times (min; p < 0.001), and between the efficacies of root canal filling material removal by the non-surgical endodontic retreatment techniques (p = 0.009). However, the non-surgical endodontic retreatment systems allow for similar carrier-based root canal filling material removal.

An 8-year prospective clinical investigation on the survival rate of feldspathic veneers: Influence of occlusal splint in patients with bruxism.

OBJECTIVES: The aim of this study was to perform a 8-year prospective clinical investigation on the survival rate of feldspathic ceramic veneers, as well as analyse the influence of the occlusal splint in patients with parafunctional bruxism. METHODS: Three hundred and sixty-four veneers fabricated using conventional feldspathic ceramic were provided in 64 patients. The patient sample included 40 individuals with bruxism. During the follow-up period, the effect of wearing the occlusal splint on the incidence of failure (fracture and/or debonding) in patients with bruxism was also assessed. The survival rate of veneers was determined using the Kaplan-Meier estimator. Statistical significance was set at p < 0.05 with a confidence interval of 95%. RESULTS: The occurrence of fracture for the feldspathic veneers tested in this study was 7.7%, while only 1.9% of the total number of veneers debonded. The overall survival rate was 93.7% after 3 years, 91% after 5 years, and 87.1% after 8 years. Patients with bruxism using an occlusal splint showed a survival rate of 89.1% after 7 years, while the survival rate in patients with bruxism using no occlusal splint was 63.9% (p < 0.05). CONCLUSION: This study confirmed that feldspathic veneers may represent a suitable clinical solution for indirect aesthetic restorations. Such a treatment may be an option also for those patients affected by bruxism, as long as they regularly wear an occlusal splint. However, patients with bruxism using no occlusal splint may still present a potential high-risk of failure and/or debonding.

Comparison of Obturation Removal Efficiency from Straight Root Canals with ProTaper Gold or Reciproc Blue: A Micro-Computed Tomography Study.

BACKGROUND: The objective was to evaluate the efficiency of ProTaper Gold (PTG) and Reciproc Blue (RB) NiTi files in obturation material removal from straight root canals assessed by micro-computed tomography. METHODS: Fifty-two anterior human teeth were shaped with a PTG rotary system until F2 (25/.08). Specimens were obturated with a continuous wave of condensation technique. For retreatment, specimens were randomly distributed in two experimental groups: PTG group (F4 file) and RB (R40 file). Micro-CT scans were performed before and after retreatment procedures. The percentage of the remaining obturation material compared to the original volume was calculated, as well as the retreatment time. The presence of separated files was recorded. A descriptive analysis was carried out, and nonparametric tests were employed. RESULTS: The mean percentages of remaining obturation material in the PTG group and the RB group were 4.14 ± 4.30% and 4.18 ± 4.29%, respectively. The mean retreatment times for the PTG and RB groups were 144 ± 51 and 163 ± 88 s, respectively. There were no statistically significant differences, neither in removal efficiency (p > 0.05) nor in retreatment time (p > 0.05), between the two groups. The coronal and middle thirds presented significantly more remaining obturation material than the apical third (p < 0.05). No file separation occurred. CONCLUSIONS: ProTaper Gold and Reciproc Blue present with comparable efficiency in removing the obturation material, with a similar mean retreatment time.

Bleaching in vital teeth: Combined treatment vs in-office treatment.

BACKGROUND: The aim of this study was to verify that there will be greater whitening in teeth treated with combined bleaching than in those that have been applied a clinical one and to evaluate the efficiency of the clinical treatment, those cases in which it is not able, or it is not wanted, to carry out the home phase. MATERIAL AND METHODS: They were used 66 extracted anterior human teeth, which were divided into two study groups. On the one hand, the clinical group (ClG) consisted of 33 teeth, which were treated with a clinical guideline using 37.5% hydrogen peroxide in a single session of 4 applications of 8 minutes. On the other hand, the combinate group (CoG) consisted of 33 teeth, which were treated with a combined guideline, applying first a clinical treatment as in the ClG and, at home treatment with carbamide peroxide at 16% for 22 days, 90 minutes a day. The colour of the tooth was measured before and after each treatment and was made through an individualized whitening splint with a spectrophotometer. RESULTS: The 66 teeth were bleached, showing an increase in luminosity, a drecrease in yellow and a shift towards the green colours, where b (yellow-blue axis) was the only variable with a statistically significant change (p<0.001). The CoG obtained a significantly higher absolute value (p<0.001) than the ClG, being 12.99 for the first one and 19.70 for the second one. CONCLUSIONS: Combined therapy bleached more than clinical one, but both techniques were effective. In addition, it is affirmed that the clinical could be an alternative in those cases in which it is not able, or it is not wanted, to carry out the home phase. Key words:Carbamide peroxide, CIELab, combined guidelines, dental bleaching, hydrogen peroxide.

An in vitro cyclic fatigue resistance comparison of conventional and new generation nickel-titanium rotary files.

BACKGROUND: New designs and processing of Niquel-Titanium (NiTi) have been introduced to increase resistance to cyclic fatigue. The purpose of this study was to compare the cyclic fatigue resistance of 3 NiTi rotary instruments, ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), Profile Vortex Blue (PVB; Dentsply Tulsa Dental, Tulsa, OK, USA) and ProTaper Universal (PTU; Dentsply Maillefer, Ballaigues, Switzerland). MATERIAL AND METHODS: A cyclic fatigue test was conducted operating instruments from ProTaper Next X2, Profile Vortex Blue 25.06 and ProTaper F2. A total of 234 instruments were rotated in 2 simulated stainless steel curved canals with different angles of curvature (45º and 60°) and 5-mm radius of curvature. The number of cycles to fracture (NCF) was calculated. Data were compared using 2-way analysis of variance and post-hoc Bonferroni test in software (SPSS 15.0, Chicago, IL). Statistical significance was set at P<0.05. RESULTS: Profile Vortex Blue showed higher resistance to cyclic fatigue in both curved canals than ProTaper Next and ProTaper Universal (P<0.001). ProTaper Universal obtained the lowest resistance to cyclic fatigue in both canals (P<0.001). CONCLUSIONS: Profile Vortex Blue was the most resistant to cyclic fatigue failure, followed by ProTaper Next and ProTaper Universal. Anatomical complexity (angle of curvature) and manufacturing process of NiTi are important factors for resistance to cyclic fatigue. Key words:Cyclic fatigue, M-Wire, Protaper Next, ProTaper Universal, Profile Vortex Blue.

Lip repositioning technique. A simple surgical procedure to improve the smile harmony.

Excessive gingival display is an esthetic concern for patients. It is a condition in which an overexposure of the maxillary gingiva (>3mm) is present during smiling. There are different etiologies of a gummy smile, such as vertical maxillary excess, short and hyperactive upper lip, altered passive eruption, anterior dentoalveolar extrusion, or a combination of these causes. The correct diagnosis of all etiologic factors is imperative for its appropriate management. Many techniques have been used to restore the dentogingival relation for the management of gummy smile. Lip repositioning is a conservative surgical technique used to treat excess gingival display. It is a largely unknown treatment modality. This limits lip elevation on smiling and increases lip fullness. This technique was designed to be shorter, less aggressive and to have fewer postoperative complications compared to orthognathic surgery. In the current case series presents three patients who were successfully managed with lip repositioning. The aim of this article is to describe the lip repositioning technique to decrease gummy smile by a simple surgical procedure. Key words:Lip repositioning, gummy smile, smile harmony.

Orthodontics and veneers to restore the anterior guidance. A minimally invasive approach.

Tooth wear is defined as the progressive loss of a tooth's surface due to actions other than those which cause tooth decay or dental trauma. It is a pathological condition with an increasing prevalence among young people. The aim of this article is to describe an alternative treatment modality to rehabilitate the anterior guidance by a minimally invasive interdisciplinary ortho-restorative treatment. Two patients came to the dental clinic for restorative treatment in order to rehabilitate the worn anterior dentition. Clinical analysis showed tooth surface loss located at the incisal edges by attrition due to an inadequate anterior guidance. In both cases the occlusal vertical dimension was reduced. First, following Dahl's principle, resin attachments were placed in the upper canines. These attachments allowed the extrusion of posterior teeth in order to increase the occlusal vertical dimension. Furthermore, anterior teeth were intruded in order to create space for the restorative material. In the second phase, the restorative treatment was completed. Due to the characteristics of the case, feldspathic ceramic veneers were indicated. A diagnostic wax-up was performed to assist the treatment planning and a mock-up was prepared. Then, maxillary incisors were prepared through the mock-up to ensure a minimally invasive technique. Afterwards, silicone impressions were taken. Finally, veneers were cemented with a light-cured cement. In the present case, the functional and aesthetic parameters required by the patients were achieved, thus satisfying their needs. Key words:Tooth wear, anterior guidance, feldspathic veneers, Dahl's principle, minimally invasive.