Lesiones perirradiculares asociadas a primeros molares superiores tratados endodónticamente: estudio a través de tomografías computadas / Periradicular lesions associated with endodontically treated maxillary first molars: study through computed tomography

Objetivos: Estudiar con tomografías computadas de haz cónico (CBCT) las lesiones perirradiculares de primeros molares superiores tratados endodónticamente; evaluar la lo- calización y, en los que tenían lesión en la raíz mesiovestibu- lar (MV), evaluar la frecuencia del conducto MV2. Materiales y métodos: A partir de una muestra de 179 tomografías, que incluían primeros molares superiores, se seleccionaron y analizaron aquellas en las cuales estos ha- bían recibido un tratamiento endodóntico previo, presentaban lesiones perirradiculares y conservaban una restauración co- ronaria. Las variables analizadas fueron: la localización de áreas radiolúcidas compatibles con lesiones perirradiculares de origen endodóntico y la correlación entre diferentes loca- lizaciones y la calidad del tratamiento realizado (adecuado, defectuoso o sin tratamiento). Los datos fueron analizados mediante la prueba de chi-cuadrado y la prueba de Spearman. Resultados: De las 179 CBCT que incluían primeros molares superiores, 90 reunían las condiciones requeridas. La frecuencia de las lesiones perirradiculares fue significativa- mente mayor en la raíz MV al compararla con las raíces disto- vestibular y palatina (p<0,05). El conducto MV1 presentó un tratamiento adecuado en todos los casos. El conducto MV2 recibió un tratamiento adecuado en 4 casos (4,44%), defec- tuoso en 4 casos (4,44%) y no tratado en 82 casos (91,1%); con una diferencia estadísticamente significativa (p<0,05). Conclusiones: En la muestra analizada, la localización de lesiones perirradiculares postratamiento endodóntico en primeros molares superiores se encontró con mayor frecuencia asociada a la raíz mesiovestibular, donde en la mayoría de los casos el con- ducto MB2 no fue tratado o presentó un tratamiento defectuoso (AU)

Aim: To study with cone-beam computed tomography (CBCT) the periradicular lesions of maxillary first molars with endodontical treatment; to evaluate its localization and, in those with a mesiobuccal root (MB) injury, assess the fre- quency of the MB2 root canal. Materials and methods: From a sample of 179 tomog- raphies (CBCT) that included maxillary first molars, those in which they had received previous endodontic treatment, pre- sented periradicular lesions and had a coronary restoration were selected and analyzed. The analyzed variables were: localization of radiolucent areas compatible with periradic- ular lesions of endodontic origin and the correlation between different localizations and quality of the performed treatment (adequate, defective, or untreated). Data were analyzed by the chi-square test and the Spearman test. Results: Of the 179 CBCT that included maxillary first molars, 90 met the required conditions. The frequency of periradicular lesions was significantly higher in the MB root when compared with distobuccal and palatal roots (P<0,05). The MB1 canal presented an adequate treatment in all cas- es. The MB2 canal received adequate treatment in 4 cases (4.44%), a defective one in 4 cases (4.44%) and was untreated in 82 cases (91.1%). The differences among these frequencies were statistically significant (P<0.05). Conclusions: In the analyzed sample, the localization of periradicular lesions after endodontic treatment in maxillary first molars was associated more frequently with the mesio- buccal root in which in the majority of cases the MB2 canal was untreated or presented a defective treatment

Ability of two reciprocating Nickel-Titanium instruments for guttapercha/ sealer removal in simulated curved root canals.

The aim of this study was to compare the capacity of two reciprocating NiTi instruments in removing gutta-percha/sealer material from simulated curved root canals (SCRC). The time required for filling material removal was also recorded. Twenty SCRCs were divided into two groups of 10 (n=10) samples each. In Group 1, the SCRC were prepared to a R25 Reciproc Blue instrument (RCPB; VDW, Munich, Germany). In Group 2 the SCRC were prepared to a Primary WaveOne Gold instrument (PWOG; Dentsply, Ballaigues, Switzerland). In both groups, the canals were filled with matched-taper single gutta-percha cones and AH Plus sealer. Filling materials were removed with R25 RCPB (Group 1) and PWOG (Group 2). The amount of remaining gutta-percha/sealer was calculated at three predetermined levels of evaluation located at 2, 6 and 10 mm from the WL and expressed in percentages. Canals re-treated with RCPB contained significantly less remaining gutta-percha/sealer compared tocanalspreparedwith PWOG (P=0.02). The RCPB instruments required significantly less time to complete the retreatment procedures (P<0.01). No unwinding or instrument separation was noted. RCPB instruments removed significantly more gutta-percha/sealer from simulated curved root canals than PWOG. However, neither of the tested instruments completely removed all filling materials.

El propósito del presente estudio fue comparar la capacidad de dos instrumentos de NiTi de movimiento reciproco para remover la obturación de gutapercha/sellador durante el retratamiento de conductos curvos simulados (SCRC). El tiempo requerido para la remoción del material fue también registrado. Se utilizaron veinte (n=20) SCRC divididos en dos grupos de diez especimenes (n=10) cada uno. En el Grupo 1 los SCRC se prepararon hasta un instrumento Reciproc Blue R25 (RCPB; VDW, Munich, Germany). En el Grupo 2, los SCRC se prepararon hasta un instrumento WaveOne Gold Primary (PWOG; Dentsply, Ballaigues, Switzerland). En ambos grupos los conductos se obturaron con cono único de gutapercha de conicidad creciente y el sellador AH Plus. La remoción de los materiales de obturación se realizó mediante los instrumentos RCPB R25 (Grupo 1) o PWOG (Grupo 2). La cantidad de gutapercha/sellador remanente se calculó en tres niveles de evaluaciónpredeterminadosubicados a 2, 6 y 10mm de la LT, y finalmente fue expresada en porcentajes. La cantidad de gutapercha/ sellador remanente en los SCRC retratados con RCPB fue significativamente menor en comparación con los que fueron retratados con PWOG (P=0.02). Los instrumentos RCPB requirieron un tiempo significativamente menor para completar el retratamiento (P<0.01). No se observaron deformaciones o separación de los instrumentos. Los instrumentos RCPB removieron una cantidad significativamente mayor de gutapercha/sellador que los instrumentos PWOG en conductos curvos simulados. Sin embargo, ninguno de los instrumentos ensayados removió completamente los materiales de obturación.

Ability of two reciprocating Nickel-Titanium instruments for guttapercha/ sealer removal in simulated curved root canals / Análisis de la capacidad de dos instrumentos reciprocantes de Niquel-Titanio para la remoción de gutapercha/sellador en conductos curvos simulados

ABSTRACT The aim of this study was to compare the capacity of two reciprocating NiTi instruments in removing gutta-percha/sealer material from simulated curved root canals (SCRC). The time required for filling material removal was also recorded. Twenty SCRCs were divided into two groups of 10 (n=10) samples each. In Group 1, the SCRC were prepared to a R25 Reciproc Blue instrument (RCPB; VDW, Munich, Germany). In Group 2 the SCRC were prepared to a Primary WaveOne Gold instrument (PWOG; Dentsply, Ballaigues, Switzerland). In both groups, the canals were filled with matched-taper single gutta-percha cones and AH Plus sealer. Filling materials were removed with R25 RCPB (Group 1) and PWOG (Group 2). The amount of remaining gutta-percha/sealer was calculated at three predetermined levels of evaluation located at 2, 6 and 10 mm from the WL and expressed in percentages. Canals re-treated with RCPB contained significantly less remaining gutta-percha/sealer compared to canals prepared with PWOG (P=0.02). The RCPB instruments required significantly less time to complete the retreatment procedures (P<0.01). No unwinding or instrument separation was noted. RCPB instruments removed significantly more gutta-percha/sealer from simulated curved root canals than PWOG. However, neither of the tested instruments completely removed all filling materials.

RESUMEN El propósito del presente estudio fue comparar la capacidad de dos instrumentos de NiTi de movimiento reciproco para remover la obturación de gutapercha/sellador durante el retratamiento de conductos curvos simulados (SCRC). El tiempo requerido para la remoción del material fue también registrado. Se utilizaron veinte (n=20) SCRC divididos en dos grupos de diez especimenes (n=10) cada uno. En el Grupo 1 los SCRC se prepararon hasta un instrumento Reciproc Blue R25 (RCPB; VDW, Munich, Germany). En el Grupo 2, los SCRC se prepararon hasta un instrumento WaveOne Gold Primary (PWOG; Dentsply, Ballaigues, Switzerland). En ambos grupos los conductos se obturaron con cono único de gutapercha de conicidad creciente y el sellador AH Plus. La remoción de los materiales de obturación se realizó mediante los instrumentos RCPB R25 (Grupo 1) o PWOG (Grupo 2). La cantidad de gutapercha/sellador remanente se calculó en tres niveles de evaluación predeterminados ubicados a 2, 6 y 10 mm de la LT, y finalmente fue expresada en porcentajes. La cantidad de gutapercha/ sellador remanente en los SCRC retratados con RCPB fue significativamente menor en comparación con los que fueron retratados con PWOG (P=0.02). Los instrumentos RCPB requirieron un tiempo significativamente menor para completar el retratamiento (P<0.01). No se observaron deformaciones o separación de los instrumentos. Los instrumentos RCPB removieron una cantidad significativamente mayor de gutapercha/sellador que los instrumentos PWOG en conductos curvos simulados. Sin embargo, ninguno de los instrumentos ensayados removió completamente los materiales de obturación.

Root dentine thickness in C-shaped lower second molars after instrumentation: A CBCT and micro-CT study.

Stripping perforation is a possible complication in instrumentation of C-shaped canals. This study evaluated the minimum thickness of the root canal wall in C-shaped teeth after instrumentation. Twelve extracted C-shaped mandibular second molars (four teeth of type I, II and III each) were examined by CBCT (voxel size 90 µm) before and after instrumentation with WOG primary file. Micro-CT scans (voxel size 30 µm) were obtained after instrumentation. Percentage of canal wall area touched by the file and minimum thickness of dentine were measured and compared between CBCT and micro-CT. In type I C-shape canals, less than 10% of the canal wall area was touched by the instrument. In ten teeth, the shortest distance to root surface was from the instrumented area; no perforations occurred. CBCT and micro-CT measurements were in good agreement in ten cases; in two teeth, micro-CT revealed considerably shorter distance to root surface. The two shortest distances were 0.27 and 0.41 mm.