The infection control of post-and-core crown restoration / 华西口腔医学杂志

Post-and-core crown is one of the most common forms of restoration of tooth after root canal therapy (RCT). Infection control is the core objective of RCT, which is usually well realized by endodontists. However, many prosthodontists often neglect the infection control of the tooth and the maintenance of the curative effect of RCT during the process of post-and-core crown, which may lead to the failure of the final restoration. The concept of integrated crown-root treatment advocated recently requires clinicians to consider the RCT and final restoration as a whole, rather than simply divided into two parts-endodontic treatment and restorative treatment. As the core content of integrated crown-root treatment, infection control should be taken seriously by clinicians and implemented throughout the whole treatment process, especially in the restorative treatment that is easily overlooked after RCT. Therefore, this article describes the infection control of post-and-core crown restoration, classifies the tooth requiring post-and-core crown restoration, and puts forward the measures of infection control before and during post-and-core crown restoration, in order to provide reference and guidance for clinical practice.

Effect of thermal conductivity on apical sealing ability of 4 dental gutta-percha cones / 北京大学学报(医学版)

Objective:To investigate the effect of thermal conductivity on the apical sealing ability of different dental gutta-percha cones during the warm vertical condensation obturation.Methods:Four kinds of dental gutta-percha cones were used in this study:Bio-GP points (BP,B&L,Korea),large-tapered gutta-percha (DP,DENTSPLY,America),PROTAPER Universal gutta-percha points (DPP,DENTSPLY,America) and mtwo gutta-percha points (VP,VDW,Germany).Volume differences method was used to determine the main components and the thermal conductivity determinator was used to measure the thermal conductivity of these dental gutta-percha cones.Furthermore,20 cones randomly selected from each kind of dental gutta-percha cones.And 10 cones of each dental gutta-percha cones,which were cut out the part of 4 mm in length from the apical end,were heated (200 ℃) from the upper end without compression,and the temperature of the gutta perchacones surface was monitored in time by the infrared thermal imager during the whole heating process.In addition,the rest of the 10 cones of each dental gutta-percha cones were used to obturate the root canal in the transparent root canal resin model using warm vertical condensation technique.The cross-sectional surface was observed by stereomicroscope (× 40) at 1 mm and 3 mm from the working length and the gutta-percha obturation area proportion was measured and analyzed.The data were analyzed by one-way ANOVA.Results:The proportion of inorganic fillers (80.90％ ± 1.14 ％) (P ＜ 0.05) and the thermal conductivity (2.247 ± 0.002)of DP was siguificantly higher than BP (79.28％ ± 3.88％,1.179 ± 0.003),DPP (68.46％ 5.09％,0.604 ±0.001),VP (78.86％ ± 1.87％,1.150 ±0.001) (P ＜0.05).During the thermal obturation without compression at the setting temperature (200 ℃),DP could achieve 65 ℃ beyond 1 mm from the heating point,and BP,DPP and VP only reached 65 ℃ within 1 mm.After warm vertical condensation obturation,all the groups showed increased gutta-percha obturation area proportion.At the position of WL-3,DP (96.89％ ±0.03％) showed significantly higher proportion of gutta-percha obturation area than BP (95.47％ ±0.06％),DPP (95.21％ ±0.03％) and VP (95.15％ ±0.03％) (P ＜ 0.05).Conclusion:DP contains more inorganic fillers,possesses higher thermal conductivity,and leads a better apical sealing ability than BP,DPP and VP at the position of WL-3 during warm vertical condensation obturation.

The effect of semiconductor laser irradiation on root cannal seal / 实用口腔医学杂志

Objective:To evaluate the effect of semiconductor lasers irradiation after routine root canal preparation on root cannal seal.Methods:60 Single-rooted freshly extracted human teeth were randomly divided into 6 groups(n=10).The crowns were removed at the cementoenamel junction and the roots were endodontically prepared with conventional methods.The roots in groups A and B were irradiated with 1 W semiconductor laser for 20 s,in group C and D were ultrasonically washed for 1 min,in group E and F without any treatment were used as the controls.Then all the roots were filled by vertical condensation of warm gutta-percha.The root cannal seal was evaluated with microleakage measurement.The data was analyzed by ANOVA.The teeth of group B,D and F were sectioned and examined under scanning electron microscope(SEM).Results:The microleakage(mm) of group A,C and E was 1.70±0.82,2.02±0.40 and 4.56±2.72 respectively(A vs E,P0.05).SEM observation showed the melting,narrowness or closure of most dentinal tubules in group B,past and/or gutta-percha in the most dentinal tubules of group D.Conclusion:Semiconductor laser irradiation prior to root cannal filling can promote the effects of cannal seal.

A comparison of apical sealing ability of different root canal obturation techniques in oval root canals / 口腔疾病防治

Objective@# To investigate the effect of different root canal obturation techniques on apical sealing in oval root canals. @*Methods@#120 recently extracted human premolars with single oval canal were randomly divided into 6 groups, including single point obturation, warm gutta percha vertical condensation, cold lateral condensation obturation method combined with different root canal sealers (iRoot SP or AH-Plus). There're six groups in total, including single point iRoot group, warm gutta percha iRoot group, cold gutta percha iRoot group, single point AH group, warm gutta percha AH group, cold gutta percha AH group. @*Results @#Root depth of dye penetration in warm gutta percha iRoot group and warm gutta percha AH group were significantly lower than group single point iRoot group and single point AH group (P < 0.05), and root depth of dye penetration of warm gutta percha iRoot group, cold gutta percha iRoot group was less than warm gutta percha AH group, cold gutta percha group (P < 0.05), but there was no statistic difference between other groups (P > 0.05). @*Conclusion @#In root canal treatment, warm gutta-percha condensation technology can make the oval canal root achieve better sealing effect, using iRoot SP is better than using AH-Plus.

Apical sealing ability of iRoot SP in oval-root canals in vitro / 实用医学杂志

Objective To evaluate the apical sealing ability of iRoot SP root canal sealer in oval-root canal. Methods After root canals were instrumented by Mtwo, 28 premolars with oval-root canal were randomly divided into 2 groups, 14 teeth in each. The root canals were obturated with AH Plus (group A) and iRoot SP (group B) by modified continuous wave condensation technique. The apical leakage was evaluated by dye penetration method and transparent teeth technique. Results Mean depth of leakage was (0.92 ± 0.26) mm for group A and (0.84 ± 0.40) mm for group B. There was no significant difference between the two groups (t=0.506, P > 0.05). Conclusion The apical sealing ability of iRoot SP is equivalent to AH Plus in oval-root canal.

Avaliação do selamento proporcionado pelo cimento MTA e pasta LC em retro-obturações / Sealing evaluation of mineral trioxide aggregate and pasta LC in retrofilling

Este estudo teve por objetivo avaliar o selamento proporcionado por dois materiais em retro-obturações. Trinta e três dentes humanos permanentes não vivos cujos canais radiculares foram retro-obturados, foram utilizados e divididos aleatoriamente em três grupos iguais, de acordo com o material empregado: G1 = Pasta LC, G2 = MTA e G3 = LC+MTA. As amostras foram impermeabilizadas, imersas em soro fetal bovino por 48 horas e, a seguir, clivados longitudinalmente para medir a infiltração por meio de escores. O resultado dos três grupos foi semelhante depois de submetidoà análise estatística por meio do teste de Kruskal-Wallis.

The purpose of this study was to evaluate the apical sealing of two materials in root-end filling. For this, thirty-three permanent human teeth were root-end prepared divided in three groups randomly, with eleven teeth in each one. The following materials were used: G1 = Pasta LC, G2 = MTA and G3 = LC+MTA. The samples were waterproofed and immersed in fetal bovine serum for 48 hours. After, the roots were separated longitudinally for measuring the infiltration by scores. The results were similar among the groups after submitted to the analysis statistics using the test of Kruskal-Wallis.

Apical microleakage and SEM analysis of dentin surface after 980 nm diode laser irradiation

This study evaluated the effect of 980-nm diode laser on apical microleakage and intraradicular dentin morphology. Roots of 110 mandibular incisors were used in the study: 92 for microleakage test and 18 for scanning electron microscopy (SEM). Roots were randomly assigned to 3 groups according to the irrigating solution (water, NaOCl and NaOCl/EDTA) and were divided into 3 subgroups according to the laser irradiation protocol (without irradiation, irradiated at 1.5 W and irradiated at 3.0 W). Two specimens of each subgroup were prepared for SEM. The remaining roots were filled with AH Plus and gutta-percha. Apical leakage was assessed by ink penetration and data were analyzed statistically by ANOVA and Tukey-Krammer test (α=0.05). SEM analysis showed intensification of changes with increase of laser power as well as variations according to the irrigating solution. Modified smear layer was observed in specimens treated with water and irradiated with laser. Roots irrigated with NaOCl/EDTA had lower levels of infiltration (0.17 ± 0.18 mm) differing significantly (p<0.05) from those of roots irrigated with water (0.34 ± 0.30 mm), but similar (p>0.05) to those irrigated with NaOCl (0.28 ± 0.29 mm). Non-irradiated roots had lower levels of infiltration (0.10 ± 0.14 mm), differing (p<0.05) from those irradiated at 1.5 W (0.32 ± 0.22 mm) and 3.0 W (0.37 ± 0.32 mm). The 980 nm diode laser modified dentin morphology and increased apical microleakage.

Este estudo avaliou o efeito do laser de diodo 980 nm na microinfiltração apical e na morfologia intrarradicular da dentina. Raízes de 110 incisivos inferiores foram utilizadas no estudo: 92 para o teste de microinfiltração e 18 para microscopia eletrônica de varredura (MEV). As raízes foram divididas em 3 grupos de acordo com a solução irrigante (água, NaOCl e NaOCl/EDTA) e subdivididas em 3 de acordo com a irradiação laser (sem irradiação, irradiados com 1,5 W e irradiados com 3,0 W). Duas amostras de cada subgrupo foram preparadas para MEV. As raízes restantes foram preenchidas com AH Plus e guta percha. A infiltração apical foi avaliada nas raízes por meio da penetração do corante e os dados foram analisados por ANOVA e teste de Tukey-Krammer (α=0,05). Os resultados da MEV mostraram intensificação das mudanças quando se aumentou a potência do laser e variações de acordo com a solução irrigadora. Camada de smear modificada foi observada em espécimes tratados com água e irradiados com laser. Raízes irrigadas com NaOCl/EDTA tiveram níveis menores de infiltração (0,17 ± 0,18 mm) estatisticamente diferente (p<0,05) das raízes irrigadas com água (0,34 ± 0,30 mm), mas semelhante (p>0,05) aos irrigados com NaOCl (0,28 ± 0,29 mm). As raízes não irradiadas tiveram níveis menores de infiltração (0,10 ± 0,14 mm), diferente (p<0,05) de 1,5 W (0,32 ± 0,22 mm) e 3.0 W (0,37 ± 0,32 mm). O laser de diodo 980 nm alterou a morfologia da dentina e aumentou a infiltração marginal apical.

Evaluation of canal preparation for apical sealing with various Ni-Ti rotary instruments / 대한치과보존학회지

OBJECTIVES: The aim of this study was to evaluate the various NiTi rotary instruments regarding their ability to provide a circular apical preparation. MATERIALS AND METHODS: 50 single canal roots were selected, cut at the cementodentinal junction and the coronal 1/3 of the canals was flared using Gates Glidden burs. Samples were randomly divided into 5 experimental groups of 10 each. In group I, GT files, Profile 04 and Quantec #9 and #10 files were used. In Group II Lightspeed was used instead of Quantec. In Group III, Orifice shaper, Profile .06 series and Lightspeed were used. In Group IV, Quantec #9 and #10 files were used instead of Lightspeed. In Group V, the GT file and the Profile .04 series were used to prepare the entire canal length. All tooth samples were cut at 1 mm, 3 mm and 5 mm from the apex and were examined under the microscope. RESULTS: Groups II and III (Lightspeed) showed a more circular preparation in the apical 1mm samples than the groups that used Quantec (Group I & IV) or GT files and Profile .04 series.(Group V)(p < 0.05) There was no significant difference statistically among the apical 3, 5 mm samples. In 5 mm samples, most of the samples showed complete circularity and none of them showed irregular shape. CONCLUSIONS: Lightspeed showed circular preparation at apical 1 mm more frequently than other instruments used in this study. However only 35% of samples showed circularity even in the Lightspeed Group which were enlarged 3 ISO size from the initial apical binding file (IAF) size. So it must be considered that enlarging 3 ISO size isn't enough to make round preparation.

Análise in vitro da viabilidade do uso do MTA e do hidróxido de cálcio como plug apical em dentes com rizogêneze incompleta / An in vitro analysys of the viability of mta and calcium hydroxide paste as an apical plug in teeth withimature apexes

O objetivo deste trabalho foi avaliar a capacidade do MTA e o do hidróxido de cálcio de evitar asobre-obturação de guta-percha e cimento quando empregados como plug apical em dentes com ápiceincompletamente formado. Foram selecionados 24 dentes monoradiculares, incisivos centrais superiores epré-molares inferiores com ápice completo, que através de desgastes com brocas apropriadas, simulou-sea anatomia apical de dente imaturo. Os dentes foram inseridos em alvéolos artificiais e plugs apicais foramrealizados com MTA ou com hidróxido de cálcio e os canais obturados com cones moldados. Radiografiasnos sentidos mésio-distal e vestíbulo-lingual foram realizados e analisadas quanto à capacidade dos plugsde evitar extravasamento da obturação. Os resultados mostraram que o plug apical com MTA foi mais efetivoque o do hidróxido de cálcio, não ocorrendo extravasamento em nenhum caso, ao passo que no grupo doplug apical com o hidróxido de cálcio, houve o rompimento do plug em quatro casos, porém sem extrusãoda obturação.

The aim of this study was to evaluate the ability of the MTA and calcium hydroxide to avoid overextension of theguta-percha and sealer when used as an apical plug in teeth with imature apexes. Twenty-four monoradicularteeth with complete root formation were selected, and an incomplete apex was created through a specificconical bur. The teeth were placed in a artificial socket an the apical plug created with both materials. Rootcanals were filled with guta-percha and cement and the teeth radiographed in the mesial-distal and bucolingualview. The x-rays were analysed about the ability to avoid overextension of the filling materials. Theresults showed that MTA was more efficient on avoiding overextension than calcium hidroxide.

In vitro evaluation of apical sealing ability of nanomaterial / 实用口腔医学杂志

Objective:To observe apical sealing ability of two kinds of nanomaterial. Methods:40 straight human maxillary anterior teeth were randomly divided into four experimental groups of 8 samples each and two control groups of 4 samples each. The root canals were prepared using step-back technique and obturated with gutta-percha and one of the sealers by the lateral condensation technique. Group 1: Filled with zinc oxide-eugenol sealer and gutta-percha (ZOE); group 2: Filled with hydroxyapatite sealer and gutta-percha (HA); group 3: Filled with nano-zinc-oxide sealer and gutta-percha (NZO); group 4: Filled with nanohydroxyapatite sealer and gutta-percha (NHA). The teeth were placed into microleakage model. Glucose leakage from the coronal to apical was measured by the concentration of glucose in apical reservoir at 1, 2, 4, 7, 10, 15, 20, 25 and 30 days with GOD (glucose oxidase ) method. The apical sealing ability of the materials were assessed according to the concentration of glucose leakage. Results:The glucose leakage of four kinds of materials differed significantly (P