Influencia de la superficie de alineado del cuerpo de escaneado en la determinación de la posición tridimensional del implante. Estudio in vitro

INTRODUCCIÓN Para la correcta captación digital de la posición del implante se utilizan unos aditamentos denominados cuerpos de escaneado. Estos tienen morfologías diversas. Los cuerpos de escaneado deben codificar el eje axial del implante, la posición del plano de conexión, así como la presencia y localización del plano anti rotatorio del implante. La cantidad de cuerpo de escaneado visible y que por tanto influye en el alineado tridimensional no ha sido suficientemente estudiada. OBJETIVOS 1.Analizar la influencia de la superficie de alineado del cuerpo de escaneado en la determinación del eje y del centro del implante para muestras diseñadas con fines de posicionamiento rotatorio y anti rotatorio. 2.Analizar la influencia de la superficie de alineado del cuerpo de escaneado en la determinación del plano anti rotatorio para muestras diseñadas con fines de posicionamiento anti rotatorio. MATERIAL Y MÉTODO Las variables combinadas para el diseño fueron: Forma, cilindro y cono. Diámetro, 4 y 5 mm. Morfología oclusal, plana y redondeada. Elemento antirotario aL 5 y a 15% del diámetro total. Estos fueron escaneados con un escáner intraoral y posteriormente se realizó un acortamiento virtual de los mismos con el fin de medir la influencia de la superficie de alineado en la posición final de la réplica del implante digital. Se realizó una comparación entre el modelo considerado como referencia, el que fue alineado 8 mm de cuerpo de escaneado, y los sucesivos, con superficie de alineado de 7 a 1 mm. RESULTADOS. La desviación del ángulo fue inferior a 0,1° para todos los cuerpos de escaneado en modelos de 7, 6 y 5 mm. La desviación de la distancia al centro es inferior a 0,01 mm para todos los cuerpos de escaneado en modelos de 7, 6 y 5 mm. La desviación del ángulo del plano rotatorio es inferior a 0,1° para todos los cuerpos de escaneado en modelos de 7 y 6 mm. No hay suficiente evidencia estadística de diferencias entre los diferentes tamaños de cuerpo escaneado. DISCUSION Las diferentes desviaciones del ángulo del eje del implante y centro del implante son significativamente peores cuando los recortes son mayores de 4 mm. Este empeoramiento del posicionamiento tridimensional del implante va a ser representativo en función del tipo de prótesis que se vaya a realizar, ya que cuantos más implantes, y más distancia haya entre ellos, mayor será el empeoramiento del posicionamiento final de los implantes. Las características del plano anti rotatorio no introdujeron diferencias significativas y tiene, al parecer, menos importancia que las otras dos variables estudiadas, aunque parece existir cierta tendencia a la significatividad a favor de los cuerpos de escaneado con un plano anti rotatorio situado al 15% de su diámetro. CONCLUSIONES 1.La disminución de la superficie de alineado de los cuerpos de escaneado con fines rotatorios y anti rotatorios influye negativamente en la determinación del eje y del centro del implante, encontrando diferencias significativas a partir de un recorte mayor de 4 mm. 2.La disminución de la superficie de alineado de los cuerpos de escaneado con fines anti rotatorios no influye en la determinación del plano anti rotatori

Novel Digital Technique to Quantify the Area and Volume of Cement Remaining and Enamel Removed after Fixed Multibracket Appliance Therapy Debonding: An In Vitro Study

The aim of this study was to construct a novel, repeatable, reproducible, and accurate measurement protocol for the area and volume of the remaining cement after removal of fixed multibracket appliances, the area and volume of remaining cement after cement removal, the area and volume of enamel removed after cement removal, and the volume of cement used to adhere fixed multibracket appliances. A total of 30 brackets were cemented and removed with over 30 extracted teeth embedded into three experimental models of epoxy resin. The models were scanned before and after bracket placement, bracket debonding, and polishing the remaining cement. The brackets were submitted to micro-computed tomography. The standard tessellation language digital files were aligned, segmented, and re-aligned using geomorphometric software. The digital measurement technique accuracy, repeatability, and reproducibility were analyzed using Gage R&R statistical analysis. The variability attributable to the area and volume measurement techniques of the total variability of the samples was 0.70% and 0.11% for repeatability, respectively, and 0.79% and 0.01% for reproducibility, respectively. The re-alignment procedure is a repeatable, reproducible, and accurate technique that can be used to measure the area and volume of the remaining cement after removal of fixed multibracket appliances, the area and volume of remaining cement after cement removal, the area and volume of enamel removed after cement removal, and the volume of cement used to adhere the fixed multibracket appliance.Odontologí

Digital technique to analyze the wear of the slot after orthodontic treatment through fixed multibracket appliances

Introduction To assess the accuracy, repeatability and reproducibility of a measurement digital technique to quantify the wear of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment with the previous measurement traditional technique (scanning electronic microscope (SEM)). Methods A total of 100 fixed multibracket appliances were cemented during the 15 months orthodontic treatment and subsequently removed. The fixed multibracket appliances were submitted preoperatively and postoperatively to a micro-computed tomography (micro-CT) scan to obtain accurate standard tessellation language (STL) digital files of the fixed multibracket appliances and to a preoperatively and postoperatively SEM analysis. Afterwards, pre-operatively and postoperatively STL digital files of each fixed multibracket appliances were aligned using morphometric software with the best fit algorithm. Subsequently, area and volume wear of fixed multibracket appliances was identified, isolated and measured. Results The repeatability and reproducibility of the digital measurement method for the area ( mm2) and volume ( mm3) were analyzed by Gage R&R statistical analysis. The area wear of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment showed a repeatability of 3.7% and a reproducibility of 0%. The volume of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment showed a repeatability of 0.9% and a reproducibility of 5.6%. However, the traditional measurement technique showed a repeatability of 0.58% and a reproducibility of 33.01%; hence, it was repeatable but not reproducible. Conclusions The digital measurement technique is a reproducible, repeatable, and accurate method for quantifying the wear of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment.Odontologí

Cleaning and retreatment protocol for a debonded ceramic restoration

Objectives: The aim of this article is to propose a resin cement cleaning protocol for use before recementing a debonded restoration. Study Design: Ceramic samples were fabricated from IPS d.sign® and IPS e.max Press® and were treated with hydrofluoric acid etching (HF), or HF+silane (S), or HF+S+adhesive or HF+S+A+resin cement. All samples were placed in a furnace at 650º for one minute in order to attempt to pyrolyze the composite. Each step was examined under scanning electron microscopy (SEM). Results: When the cleaning protocol had been performed, it left a clean and retentive surface. Conclusions: If the restoration is placed in a furnace at 650º for one minute, the composite cement will burn or pyrolyze and disappear, allowing conventional retreatment of the ceramic before rebonding

Bonding to silicate ceramics : conventional technique compared with a simplified technique

Silicate ceramic bonding is carried out by acid-etching with hydrofluoric acid (HF) followed by an application of silane. By replacing HF with ammonium polyfluoride, contained in the same flask as the silane, the number of steps in this clinical procedure, can be reduced, while maintaining bond strength values, and reducing toxicity. A shear bond test was performed to compare the conventional and the simplified surface treatment techniques. Twenty ceramic samples were fabricated from IPS emax CAD® ceramic (Ivoclar Vivadent) and divided into two groups (G1 and G2) (n=10). The conventional technique was applied to G1 samples, and the simplified technique to G2 samples. A resin cement cylinder was bonded to each sample. Afterwards, samples underwent shear bond strength testing in a universal test machine. G1 obtained 26.53±6.33 MPa and G2 23.52±8.41 MPa, without statistically significant differences between the two groups. Monobond Etch Prime appears to obtain equivalent results in terms of bond strength while simplifying the technique. Further investigation is required to corroborate these preliminary findings

Shear bond strength of debonded ceramic restorations re-cemented by means of a cleaning and retreatment protocol

Background: As there is no standard method for re-cementing debonded partial ceramic restorations, the aim of this study was to evaluate the use of a non-invasive thermal protocol for cleaning and retreatment, and to study its influence on shear bond strength. Material and Methods: Twenty ceramic samples (IPS e.max CAD®) were bonded to composite cement cylinders and underwent a shear bond strength test (G1, n=20). A second group was created (G2, n=20), representing debonded restorations. To simulate debonding, the samples were artificially contaminated with composite cement. After debonding, these underwent a thermal protocol to remove remaining adhesive. After rebonding to the composite cement cylinders, samples underwent the shear bond strength test. Results: Median bond strengths for G1 and G2 were 7.28±3.23; 7.06±3.41 MPa, respectively, without significant difference between the groups (p=0.983). Conclusions: Debonded lithium disilicate glass-ceramic restorations should undergo a laboratory cleaning and retreatment protocol before being returned to the clinic for rebonding

Influence of occlusal collision corrections completed by two intraoral scanners or a dental design program on the accuracy of the maxillomandibular relationship.

STATEMENT OF PROBLEM Occlusal collisions of articulated intraoral digital scans can be corrected by intraoral scanners (IOSs) or dental design software programs. However, the influence of these corrections on the accuracy of maxillomandibular relationship is unclear. PURPOSE The purpose of this clinical investigation was to measure the effect of occlusal collision corrections completed by the IOSs or dental design software programs on the trueness and precision of maxillomandibular relationship. MATERIAL AND METHODS Casts of a participant mounted on an articulator were digitized (T710). The experimental scans were obtained by using 2 IOSs: TRIOS4 and i700. The intraoral digital scans of the maxillary and mandibular arches were obtained and duplicated 15 times. For each duplicated pair of scans, a bilateral virtual occlusal record was acquired. Articulated specimens were duplicated and assigned into 2 groups: IOS-not corrected and IOS corrected (n=15). In the IOS-not corrected groups, the IOS software program postprocessed the scans maintaining the occlusal collisions, while in the IOS-corrected groups, the IOS software program eliminated the occlusal collisions. All articulated specimens were imported into a computer-aided design (CAD) program (DentalCAD). Three subgroups were developed based on the CAD correction: CAD-no change, trimming, or opening the vertical dimension. Thirty-six interlandmark distances were measured on the reference and each experimental scan to compute discrepancies by using a software program (Geomagic Wrap). Root mean square (RMS) was selected to compute the cast modifications performed in the trimming subgroups. Trueness was examined using 2-way ANOVA and pairwise comparison Tukey tests (α=.05). Precision was evaluated with the Levene test (α=.05). RESULTS The IOS (P<.001), the program (P<.001), and their interaction (P<.001) impacted the trueness of the maxillomandibular relationship. The i700 obtained higher trueness than the TRIOS4 (P<.001). The IOS-not corrected-CAD-no-changes and IOS-not-corrected-trimming subgroups obtained the lowest trueness (P<.001), while the IOS-corrected-CAD-no-changes, IOS-corrected-trimming, and IOS-corrected-opening subgroups showed the highest trueness (P<.001). No significant differences in precision were found (P<.001). Furthermore, significant RMS differences were found (P<.001), with a significant interaction between Group×Subgroup (P<.001). The IOS-not corrected-trimmed subgroups obtained a significantly higher RMS error discrepancy than IOS-corrected-trimmed subgroups (P<.001). The Levene test showed a significant discrepancy in the RMS precision among IOSs across subgroups (P<.001). CONCLUSIONS The trueness of the maxillomandibular relationship was influenced by the scanner and program used to correct occlusal collisions. Better trueness was obtained when the occlusal collisions were adjusted by the IOS program compared with the CAD program. Precision was not significantly influenced by the occlusal collision correction method. CAD corrections did not improve the results of the IOS software. Additionally, the trimming option caused volumetric changes on the occlusal surfaces of intraoral scans

Shear bond strength of partial coverage restorations to dentin

Background: When partial coverage restorations (veneers, inlays, onlays...) must be cemented to dentin, bond strength may not reach the same predictable values as to enamel. The purpose of this study was: 1. To compare, with a shear bond test, the bond strength to dentin of a total-etch and a self-etching bonding agent. 2. To determine whether creating microretention improves the bond strength to dentin. Materials and methods: Two bonding agents were assayed, Optibond FL® (Kerr), two-bottle adhesive requiring acid etching, and Clearfil SE Bond® (Kuraray), two-bottle self-etching adhesive. The vestibular, lingual, distal and mesial surfaces of ten molars (n=10) were ground to remove all enamel and 40 ceramic samples were cemented with Variolink II® (Ivoclar Vivadent). Half the molar surfaces were treated to create round microretention (pits) to determine whether these could influence bond strength to dentin. The 40 molar surfaces were divided into four groups (n=10): Optibond FL (O); Clearfil SE (C); Optibond FL + microretention (OM); Clearfil SE + micro retention (CM). A shear bond test was performed and the bond failures provoked examined under an optical microscope. Results: O=35.27±8.02 MPa; C=36.23±11.23 MPa; OM=28.61±6.27 MPa; CM=27.01±7.57 MPa. No statistically significant differences were found between the adhesives. Optibond FL showed less statistical dispersion than Clearfil SE. The presence of microretentions reduced bond strength values regardless of the adhesive used. Conclusions: 1. Clearfil SE self-etching adhesive and Optibond FL acid-etch showed adequate bond strengths and can be recommended for bonding ceramic restorations to dentin. 2. The creation of round microretention pits compromises these adhesives’ bond strength to dentin

A reproducible and repeatable digital method for quantifying nasal and sinus airway changes following suture palatine expansion

[EN] Purpose The airway complex is modifed by palatine expansion. Computer tomography has been used in the past to determine the change in volume, but there was a lack of a specifc, reproducible method for this purpose. The present study sought to determine the accuracy, reproducibility, and repeatability of an innovative digital measurement technique for analyzing the volume of maxillary and nasal sinus airways following suture palatine expansion performed with the Hyrax disyuntor appliance.Methods Patients underwent preoperative and postoperative cone-beam computed tomography (CBCT) scans. The datasets were subsequently uploaded into a digital treatment planning software to record the volume of the right and left maxillary sinus, as well as the nasal and maxillary sinus airway complex. The Gage Repeatability & Reproducibility statistical analysis methodology was used to evaluate the repeatability and reproducibility of this measurement technique when measuring the volume of maxillary and nasal sinus airways following suture palatine expansion with the Hyrax disyuntor appliance. Additionally, comparative analysis between preoperative and postoperative measures was performed using Student’s t-test for statistical analysis.Results In 5 patients, paired t-tests found statistically signifcant diferences before and after treatment in the volumes of the left maxillary sinus (p=0.002), right maxillary sinus (p=0.001), and nasal and maxillary sinus airway complex (p=0.005) after suture palatine expansion with the Hyrax disyuntor appliance. Conclusion The proposed digital technique is an accurate, repeatable, and reproducible measurement technique for analyzing the volume of maxillary and nasal sinus airways following suture palatine expansion using the Hyrax disyuntor.Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCLE

Influence of Drilling Technique on the Radiographic, Thermographic, and Geomorphometric Effects of Dental Implant Drills and Osteotomy Site Preparations

The aim of this comparative study is to analyze the influence of drilling technique on the radiographic, thermographic, and geomorphometric e ects of dental implant drills and osteotomy site preparations. One hundred and twenty osteotomy site preparations were performed on sixty epoxy resin samples using three unused dental implant drill systems and four drilling techniques performed with a random distribution into the following study groups: Group A: drilling technique performed at 800 rpm with irrigation (n = 30); Group B: drilling technique performed at 45 rpm without irrigation (n = 30); Group C: drilling technique performed at 45 rpm with irrigation (n = 30); and Group D: drilling technique performed at 800 rpm without irrigation (n = 30). The osteotomy site preparation morphologies performed by the 4.1 mm diameter dental implant drills from each study group were analyzed and compared using a cone beam computed tomography (CBCT) scan. The termographic e ects generated by the 4.1 mm diameter dental implant drills from each study group were registered using a termographic digital camera and the unused and 4.1 mm diameter dental implant drills that were used 30 times from each study group were exposed to a micro computed tomography (micro-CT) analysis to obtain a Standard Tessellation Language (STL) digital files that determined the wear comparison by geomorphometry. Statistically significant di erences were observed between the thermographic and radiographic results of the study groups (p < 0.001). The e ect of cooling significatively reduced the heat generation during osteotomy site preparation during high-speed drilling; furthermore, osteotomy site preparation was not a ected by the wear of the dental implant drills after 30 uses, regardless of the drilling technique.Odontologí