Influence of Hero Apical instruments on cleaning ovoid-shaped root canals

The cleaning capacity of Hero 642 nickel-titanium files, complemented by the Hero Apical instruments in flattened roots, was determined by histological analysis, considering the area of action of the instruments on the coronal walls and the presence of remaining debris. Twenty-four single-canal, human mandibular incisors were divided into three groups and prepared as follows: GI, instrumented with Hero 642 NiTi files 30/.06, 25/.06, 20/.06, 25/.06, and 30/.06; GII, instrumented as GI followed by Hero Apical size 30/.06; GIII, instrumented as GI followed by Hero Apical sizes 30/.06 and 30/.08, then returning to 30/.06 with pendulum movements. The apical thirds were prepared for histological processing, analyzed at 40× magnification and the images were examined morphometrically. Statistical analysis showed that GIII presented the best results for removing debris (5.22% ± 4.13), with more contact between the instruments and the root canal walls (19.31% ± 0.15). This differed statistically from GI (14.04% ± 4.96 debris removal, with 42.96% ± 7.11 instrument contact) and GII (12.62% ± 5.76 debris removal, with 35.01% ± 0.15 instrument contact). Root canal preparation with Hero 642, complemented by Hero Apical instruments (30/.06 and 30/.08, then re-instrumented with Hero Apical 30/.06 using pendulum movements), was more efficient for debris removal and allowed more contact of the instruments with the root canal walls. GII presented the worst results.

Efficacy of Profile .04 taper series 29 in removing filling materials during root canal retreatment-an in vitro study

Objective. The aim of this study was to compare Profile .04 taper series 29 instruments and hand files for gutta-percha removal. Study design. Twenty maxillary central incisors with a single straight canal were instrumented and filled. The teeth were divided into 2 groups of 10 specimens each, according to gutta-percha removal techniques: Group 1- Profile series 29 and Group 2- hand files and solvent. The amount of time for gutta-percha removal and the number of fractured instruments were evaluated. Radiographs were taken and the teeth were grooved longitudinally and split. The area of residual debris was measured using computer software. Results. The time for filling material removal was significantly shorter when Profile series 29 was used (P = .00). Regarding cleanliness, there were no statistical differences in the teeth halves evaluations (P = .05). Hand instruments cleaned the canals significantly better than Profiles, in the radiographic analysis considering the whole canal. Overall, the radiographic analysis showed a smaller percentage of residual debris than the teeth halves analysis. Conclusion. The Profile series 29 instruments proved to be faster than hand instruments in removing root filling materials; however, hand instruments yielded better root canal cleanliness. Some residual debris was not visualized by radiographs. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: e46-e50)

Flat-Oval Root Canal Preparation with Self-Adjusting File Instrument: A Micro-Computed Tomography Study

Introduction: The aim of this study was to evaluate the root canal preparation in flat-oval canals treated with either rotary or self-adjusting file (SAF) by using micro-tomography analysis. Methods: Forty mandibular incisors were scanned before and after root canal instrumentation with rotary instruments (n = 20) or SAF (n = 20). Changes in canal volume, surface area, and cross-sectional geometry were compared with preoperative values. Data were compared by independent sample t test and chi(2) test between groups and paired sample t test within the group (alpha = 0.05). Results: Overall, area, perimeter, roundness, and major and minor diameters revealed no statistical difference between groups (P > .05). In the coronal third, percentage of prepared root canal walls and mean increases of volume and area were significantly higher with SAF (92.0%, 1.44 +/- 0.49 mm(3), 0.40 +/- 0.14 mm(2), respectively) than rotary instrumentation (62.0%, 0.81 +/- 0.45 mm(3), 0.23 +/- 0.15 mm2, respectively) (P < .05). SAF removed dentin layer from all around the canal, whereas rotary instrumentation showed substantial untouched areas. Conclusions: In the coronal third, mean increases of area and volume of the canal as well as the percentage of prepared walls were significantly higher with SAF than with rotary instrumentation. By using SAF instruments, flat-oval canals were homogenously and circumferentially prepared. The size of the SAF preparation in the apical third of the canal was equivalent to those prepared with #40 rotary file with a 0.02 taper. (J Endod 2011;37:1002-1007)

Histological evaluation of the effectiveness of increased apical enlargement for cleaning the apical third of curved canals

P>Objective To evaluate the influence of apical size on cleaning of the apical third of curved canals prepared with rotary instruments. Methodology Forty-four mesiobuccal canals of maxillary molars teeth were instrumented to different apical sizes (30, 0.02; 35, 0.02; 40, 0.02; 45, 0.02) using a crown-down technique. After canal preparation, the apical thirds of the roots were submitted to histological processing and examination. The specimens were analysed at 40x magnification and the images were submitted to morphometric analysis with an integration grid to evaluate the percentage of debris and uninstrumented root canal walls. The action of the instruments on the root canal walls was assessed based on the surface regularity, abrupt change on the continuity of root canal walls, and partial or total pre-dentine removal. The results were statistically compared using one-way anova with post hoc Tukey test. Pearson`s correlation was performed to identify potential correlations between values. Results The percentage of uninstrumented root canal dentine was higher when apical enlargement was performed with instruments 30, 0.02 taper (55.64 +/- 4.62%) and 35, 0.02 taper (49.03 +/- 5.70%) than with instruments 40, 0.02 taper (38.08 +/- 10.44%) and 45, 0.02 taper (32.65 +/- 8.51%) (P < 0.05). More debris were observed when apical enlargement was performed with instruments 30, 0.02 taper (34.62 +/- 9.49%) and 35, 0.02 taper (25.33 +/- 7.37%) (P < 0.05). There was a significant correlation between the amount of remaining debris and the perimeter of uninstrumented root canal dentine (r = 0.9130, P < 0.001). Conclusion No apical enlargement size allowed the root canal walls to be prepared completely. Apical third cleanliness could be predicted by instrument diameter.

Canal transportation and centring ability of RaCe rotary instruments

Evaluate, through computerized tomography, canal transportation and centring ability of RaCe rotary instruments after preparation of mesiobuccal root canals in maxillary molar teeth. Twenty-seven teeth were submitted to three cone beam tomographic analyses, one preoperatively, and two after preparation with file size 35, .02 taper and size 50, .02 taper. Canal transportation and centring ability were measured with reference to the distance between the noninstrumented portion of the root canals and the mesial and distal periphery of the root, compared with images obtained after the preparation with size 35 and 50 instruments. Canal transportation after preparation with the size 35 file was 0.030 +/- 0.253 mm and after the size 50 file was 0.057 +/- 0.317 mm. The centring ratio values after preparation with the size 35 file was 0.42 +/- 0.32 and after the size 50 file was 0.54 +/- 0.29, with no significant statistical difference between the groups. RaCe instruments allowed the preparation of curved root canals with preparation diameters larger than those normally used with minimal canal transportation and adequate centring ability.

Determination of Ni(II) in metal alloys by spectrophotometry UV-Vis using dopasemiquinone

A spectrophotometric method was proposed for Ni(II) determination in alloys using a dopa-semiquinone (L-1) to form [Ni(II)(L1-)3]1-, ε = 9.3 x 10³ L mol-1 cm-1. The optimal conditions for the determination were: wavelength 590 nm, temperature 25 °C, reaction time 45 min and pH 7.5. The Beer's law was obeyed for nickel from 3.33 x 10-5 to 1.78 x 10-4 mol L-1. The method was applied to complex samples, such as inox, nickel-titanium and cobalt-chromium alloys. A study of the potential interferents revealed that Mn was the major interferent. The limit of detection and quantification were 2.88 x 10-5 mol L-1 and 3.06 x 10-5 mol L-1, respectively.

Influence d’un rince-bouche fluoré sur la corrosion galvanique entre un fil NiTi ou un fil CuNiTi et différents boîtiers orthodontiques : incidence sur les propriétés mécaniques des fils

Objectif : il a été rapporté que l’utilisation d’agents prophylactiques fluorés pouvait favoriser la corrosion galvanique au sein des alliages de titane. L’objectif de la présente étude était d’évaluer l’effet d’un rince-bouche fluoré sur les propriétés mécaniques de fils en nickel-titane (NiTi) et de fils en cuivre-nickel-titane (CuNiTi) lorsque ces derniers sont couplés à des boîtiers de compositions différentes (boîtiers de marques Smartclip, Clarity, et Sprint). Matériels et Méthodes : 90 segments de fils en NiTi et 90 segments de fils en CuNiTi ont été chacun couplés à 2 boîtiers de chaque marque. Chaque assemblage fil-boîtiers a été par la suite incubé pendant 3 heures à 37°C, soit dans une solution de fluore neutre (Fluorinse™ 0,05% NaF), soit dans une solution de salive artificielle (solution contrôle). Suite à l’incubation, les échantillons étaient nettoyés avec de l’eau déshydrogénée, les fils séparés des boîtiers et montés sur un support pour subir un test de pliage en trois points en milieu humide (salive artificielle) à 37°C. Les modules d’élasticité ainsi que les limites conventionnelles d’élasticité en activation et en désactivation ont été mesurés et comparés. Des analyses de Variance (ANOVA) et des comparaisons post-hoc avec la correction de Bonferronni ont été utilisées pour comparer les groupes entre eux (α = 0,05). Résultats : L’utilisation d’un rince-bouche fluoré a produit une réduction du module d’élasticité et de la limite conventionnelle d’élasticité en activation et en désactivation pour les fils en NiTi ; cependant, cet effet a été modulé par le type de boîtier auquel le fil a été couplé. Les propriétés mécaniques de fils en CuNiTi n’ont pas été affectées par le fluor, ou par le type de boîtier utilisé. Conclusions : L’utilisation d’un rince-bouche fluoré modifie les propriétés mécaniques des fils en NiTi seulement. Cet effet est modulé par le boîtier auquel le fil en NiTi est couplé. A la différence des autres études publiées dans la littérature, nos résultats ne nous permettent pas de conclure que la modification des propriétés mécaniques des fils en NiTi entrainerait obligatoirement un allongement de la durée du traitement orthodontique. Mots clés : Fluor, fils nickel-titane, boîtiers orthodontiques, corrosion galvanique, propriétés mécaniques.

Effect of osteogenesis imperfecta on orthodontic tooth movement in a mouse model

Thesis written in co-mentorship with director: Nelly Huynh; co-directors: Frank Rauch and Jean-Marc Retrouvey; collaborators: Clarice Nishio, Duy-Dat Vu and Nathalie Alos

Análise radiográfica computadorizada da reabsorção radicular apical após a utilização de duas mecânicas ortodônticas

OBJETIVO: a reabsorção radicular apical é uma condição comumente observada durante e após o tratamento ortodôntico e fatores como tipo de aparelhagem ortodôntica utilizada, magnitude das forças aplicadas e duração do tratamento podem estar relacionados ao processo de arredondamento do ápice radicular. Buscou-se avaliar, por meio de imagens radiográficas computadorizadas, a quantidade de reabsorção no ápice radicular, quando da utilização de duas diferentes técnicas de mecânica ortodôntica fixa: Edgewise com acessórios padrão e Edgewise com acessórios totalmente programados. METODOLOGIA: a amostra constituiu-se de 20 pacientes tratados pelo mesmo profissional na Clínica de Ortodontia da Faculdade de Odontologia de Araçatuba - UNESP. Os pacientes foram divididos em dois grupos: grupo 1 (Tratados com Edgewise com acessórios padrão e fios de aço) e grupo 2 (Tratados com Edgewise com acessórios totalmente programados e fios de níquel-titânio). A avaliação radiográfica digital foi realizada por um único operador por meio de exposições radiográficas digitais feitas no início do tratamento ortodôntico, após retração de caninos e final de tratamento, utilizando o sistema de escores proposto por Levander e Malmgren (1988). RESULTADOS E CONCLUSÕES: a análise dos escores permitiu concluir que o tratamento ortodôntico empregando a técnica Edgewise com acessórios totalmente programados e fios de níquel-titânio apresentou menores graus de reabsorção radicular apical, em comparação à técnica Edgewise com acessórios padrão e fios de aço. Observou-se que, independentemente da técnica empregada, o tratamento ortodôntico como um todo apresentou um grau moderado de reabsorção radicular apical.

Intrusion of teeth with class III furcation: a clinical, histologic and histometric study in dogs

Aim: To assess orthodontic intrusion effects on periodontal tissues in dogs' pre-molars with class III furcations treated with open flap debridement (OFD) or with guided tissue regeneration (GTR) associated to bone autograft (BA).Material and Methods: Class III furcations were created in the pre-molars of seven mongrel dogs. After 75 days, teeth were randomly treated with OFD or GTR/BA. After 1 month, metallic crowns were assembled on pre-molars and connected apically to mini-implants by nickel-titanium springs. Teeth were randomly assigned to orthodontic intrusion (OFD+I and GTR/BA+I) groups or no movement (OFD and GTR/BA) groups. Dogs were sacrificed after 3 months of movement and 1 month retention.Results: All class III furcations were closed or reduced to class II or I in the intrusion groups, while 50% of the lesions in non-moved teeth remained unchanged. Intruded teeth presented higher probing depth and lower gingival marginal level than non-moved teeth (p < 0.01). Clinical attachment gain was reduced in the intrusion groups by the end of retention (p < 0.05). OFD+I presented smaller soft tissue area and larger bone tissue area than other groups (p < 0.05).Conclusion: Orthodontic intrusion with anchorage via mini-implants improved the healing of class III furcation defects after OFD in dogs. GTR/BA impaired those results.

Performance of race instrumentation system in curved root canals: a comprehensive analysis by three study methods

In this study, curved maxillary molar root canals were instrumented with RaCe rotary system to evaluate: 1. the occurrence of canal transportation using a radiographic platform; 2. the action of the instruments on the dentin walls, centering ability and canal enlargement by analysis of digital images; and the percentage of regular dentin surfaces and debris within the canal by histological analysis. Ten mesiobuccal roots of extracted human maxillary molars were embedded in acrylic resin and sectioned at the middle and apical thirds. Root canal shaping was performed using the RaCe rotary system at 250 rpm and 1 Ncm torque. Each instrument set was used five times according to a crowndown technique in the following sequence: 40/0.10, 35/0.08, 25/0.06, 25/0.04, 25/0.02 (working length - WL), 30/0.02 (WL) and 35/0.02 (WL). Each instrument was inserted until resistance was felt and then pulled back, followed by brushing movements towards all canal walls. Each specimen was assessed by three study methods: radiographic platform, digitized image assessment and histological analysis. The radiographic platform showed lack of apical transportation. No statistically significant difference (Wilcoxon test, p>0.05) was found between the middle and apical thirds regarding instrument action on dentin walls, centering ability, area of root canal enlargement, percentage of regular dentin surfaces and debris within the root canal. It may be concluded that RaCe system is a suitable method for the preparation of curved root canals, regarding the maintenance of root canal original path, action on dentin walls, canal enlargement and removal of debris from the root canal lumen.