A three-dimensional evaluation of microleakage of class V cavities prepared by the very short pulse mode of the erbium:yttrium-aluminium-garnet laser.

The aim of this study was to evaluate microleakage along resin restoration in cavities prepared with an erbium:yttrium-aluminium-garnet (Er:YAG) laser, with and without acid etching, and to compare it with that in diamond-drilled cavities. Thirty intact molars were divided into three equal groups. In the teeth in group I, class V cavities were prepared with a diamond drill. Cavities in groups II and III were prepared with an Er:YAG laser (400 mJ/15 Hz for enamel and 250 mJ/10 Hz for dentine). The cavities in groups I and II were acid-etched and adhesive and flowable composite were applied to all cavities. The specimens were first immersed in dye for 24 h and then in 5% nitric acid for 72 h for softening. The fillings were extracted and photographed through a dissecting microscope. The leakage area was measured with specially designed software. The Kruskal-Wallis test showed that the best ranking was group II [mean range (m.r.) = 27.46], followed by group I (m.r. = 33.48) and, lastly, group III (m.r. = 45.15). The differences between groups I and III (P = 0.023) and between groups II and III were statistically significant (P = 0.080). The least microleakage was found in those cavities prepared by Er:YAG laser and subsequently acid-etched, whereas the most leakage was in the lased cavities that had not been etched; the traditional diamond-drilled acid-etched cavities produced medium leakage.

Longitudinal study on the influence of Nd:YAG laser irradiation on microleakage associated with two filling techniques.

OBJECTIVE: This study investigates the effects of Nd:YAG laser irradiation on apical and coronal seals, when used prior to two root canal filling techniques. BACKGROUND DATA: Limited information exists regarding the effects of morphologic changes to dentin walls following Nd:YAG laser irradiation on the sealing ability of root fillings. METHODS: Two hundred forty teeth were analyzed by observing coronal and apical leakage of Indian ink (DL), and 60 were analyzed for through-and-through leakage using the fluid transport model (FTM). The Nd:YAG laser parameters were 1.5 W, 100 mJ, and 15 Hz (four times for 5 s at 20 s intervals). Each group consisted of a lased and a nonlased subgroup: each subgroup had root fills done by either cold lateral condensation (CLC) or hybrid condensation (HC). Leakage was assessed after 48 h, and then at 1, 6, and 12 months. The DL group was divided into four groups of 15 teeth for each evaluation point. Through-and-through leakage (L in microliters/day) was measured for 48 h under a pressure of 1.2 atm using FTM, and recorded as L = 0 (L1), 0 < L 10 (L3). RESULTS: Apical and coronal dye leakage was observed in all groups. Significant differences (p < 0.05) in apical leakage were found between HC and HC + Nd after 1, 6, and 12 months, and between CLC and CLC + Nd at 6 and 12 months. No significant differences were found between laser-irradiated and non-laser-irradiated groups with FTM. CONCLUSION: Pulsed Nd:YAG laser irradiation following root canal preparation may reduce apical leakage in association with hybrid gutta-percha condensation.

Effects of different irrigation regimens on the sealing properties of repaired furcal perforations.

OBJECTIVE: The pulp chamber is inevitably exposed to irrigants during endodontic therapy. This study aimed to investigate whether different irrigation regimens would alter the sealing ability of repaired furcal perforations. STUDY DESIGN: Pulp chambers of 90 extracted human molars were accessed, after which standardized diamond bur-cut perforations were created in the center of the pulp chamber floor. The canal orifices and the apical end of roots were sealed with acid-etch composite resin. Eighty teeth were randomly divided into 2 groups (n = 40/group) according to the material used for repairing the perforation defects: (1) Mineral trioxide aggregate (MTA), (2) Super-EBA. The remaining teeth (n = 10) served as controls. The specimens were further subgrouped according to the irrigation regimens applied over the repair site (n = 10/group): (a) 5.25% NaOCl, (b) 5.25% NaOCl + EDTA, (c) 5.25% NaOCl + MTAD, and (d) No irrigation. Coronal leakage was measured by the fluid-filtration method at 1 day and 1 week. RESULTS: Fluid conductance was not affected by the type of repair material (P = .964) or time (P = .726), but was affected significantly by the irrigation regimens in the following ranking: (P < .001): NaOCl < or = No Irrigation < NaOCl + MTAD < or = NaOCl + EDTA. CONCLUSION: The sealing ability of furcal perforations repaired with MTA or Super-EBA were differentially affected by exposure to the tested irrigation regimens.

Microleakage on Class V glass ionomer restorations after cavity preparation with aluminum oxide air abrasion.

This in vitro study assessed the marginal microleakage on class V cavities prepared with aluminum oxide air abrasion and restored with different glass ionomer cements. The cavities were prepared on the buccal and lingual surfaces of 15 sound third molars with an air- abrasion device (Kreativ Mach 4.1; New Image) using a 27.5-microm aluminum oxide particle stream, and were assigned to 3 groups of 10 cavities each. The restorative materials were: group I, a conventional glass ionomer cement (Ketac-Fil); groups II and III, resin-modified glass ionomer cements (Vitremer R and Fuji II LC, respectively). After placement of the restorations, the teeth were stored in distilled water at 37 degrees C for 24 h, polished and then submitted to a thermocycling regimen of 500 cycles, isolated, immersed in 0.2% Rhodamine B solution for 24 h, included and serially sectioned. Microleakage was assessed by viewing the specimens under an optical microscope connected to a color video camera and a computer. The images obtained were digitized and analyzed for microleakage using software that allows for a standard quantitative assessment of dye penetration in millimeters. Statistical analysis was done using the Kruskall-Wallis and Wilcoxon tests. Means of dye penetration (%) were: occlusal - I: 25.76 +/- 34.35, II: 20.00 +/- 42.16, III: 28.25 +/- 41.67; cervical - I: 23.72 +/- 41.84; II: 44.22 +/- 49.69, III: 39.27 +/- 50.74. No statistically significant differences (p>0.05) were observed among either the glass ionomer cements or the margins. In conclusion, class V cavities restored with either conventional or resin-modified glass ionomer cements after preparation with aluminum oxide air abrasion did not show complete sealing at the enamel and dentin/cementum margins.

Microleakage on class V glass ionomer restorations after cavity preparation with aluminum oxide air abrasion

Este estudo in vitro avaliou a microinfiltração marginal em cavidades classe V preparadas com jato de óxido de alumínio e restauradas com diferentes sistemas ionôméricos. As cavidades foram preparadas nas superfícies vestibular e lingual de 15 terceiros molares hígidos e foram divididas em três grupos com 10 cavidades cada um. Os seguintes materiais foram utilizados: no grupo I, cimento de ionômero de vidro convencional (Ketac Fil) e nos grupo II e III, cimentos de ionômero de vidro modificado por monômeros resinosos (Vitremer e Fuji II LC, respectivamente). O preparo cavitário foi realizado por meio da aplicação do jato de óxido de alumínio (Kreativ Mach 4.1; New Image), com partículas de 27,5 µm. Após a restauração das cavidades, os dentes foram armazenados durante 24 h em água destilada a 37ºC, polidos e então submetido a termociclagem (500 ciclos), imersos em Rodamina B a 0,2% por 24 h, incluídos e seccionados. A análise da microinfiltração marginal foi realizada por meio de um microscópio óptico acoplado a uma câmera e a um computador. As imagens obtidas foram digitalizadas e analisadas utilizando um software que permite uma análise quantitativa padronizada da microinfiltração, em milímetros. As médias (%) obtidas foram: oclusal - I: 25,76 mais ou menos 34,35; II: 20,00 mais ou menos 42,16; III: 28,25 mais ou menos 41,67; cervical I: 23,72 mais ou menos 41,84; II: 44,22 mais ou menos 49,69; III: 39,27 mais ou menos 50,74. Os dados foram submetidos à análise estatística, utilizando os testes de Kruskall-Wallis e Wilcoxon. Não houve diferença estatisticamente significante (p>0.05) entre os materiais testados nem entre as margens oclusal e cervical. Conclui-se que em cavidades classe V preparadas com ar abrasão e restauradas com cimentos de ionômero de vidro convencional e modificados por monômeros resinosos não houve completo vedamento marginal.

Microleakage at the composite-repair interface: effect of different surface treatment methods.

This study evaluated microleakage at the composite-repair interface after using different methods of surface treatment. Eighty resin composite specimens (Filtek Z250, 3M Dental Products) aged in artificial saliva for three months were divided into four groups (n=20) according to the following surface treatment methods: untreated control-no roughening or abrasion of the surface; roughening with diamond burs; jet prophylaxis with sodium bicarbonate particles and air abrasion with 50 microm aluminum oxide particles. Each method was examined using scanning electron microscopy (SEM) to evaluate changes in surface topography. All groups were then etched with 37% phosphoric acid, coated with a bonding agent (Single Bond, 3M Dental Products) and received new resin applications. The samples were then thermocycled (800 cycles/5 degrees C to 55 degrees C [+/- 2]) and immersed in 2% methylene blue buffered dye solution (7.0 pH) for four hours. Three examiners measured the extent of microleakage in a stereoscope microscope using four representative scores. For all experimental groups, no significant difference in repair microleakage was identified by the Kruskal-Wallis test (p>0.05). Therefore, different testing methods of surface treatment showed the same effect on dye penetration along the repair interface.

The effect of irrigation with doxycycline or citric acid on leakage and osseous wound healing.

This study investigated the effect of doxycycline irrigation on wound healing and the apical seal of three filling materials. Part 1: 220 extracted teeth received root canal therapy followed by root resection (2 mm) and ultrasonic root end preparations (3 mm). Groups of 20 were irrigated with saline, citric acid, or doxycycline and filled with amalgam, Super EBA, or MTA. Leakage was measured (mm) after decalcification and clearing. Part 2: two defects were made on each side of the mandible of 10 New Zealand rabbits. On each side, one defect was irrigated with saline and one with either citric acid or doxycycline. The animals were killed in groups of five at 9 and 18 days. Sections of each defect were stained with hematoxylin and eosin for evaluation of healing and bone fill. Super EBA and MTA leaked significantly less than amalgam, regardless of irrigant. Leakage after irrigation with doxycycline compared to citric acid or saline was not significantly different for Super EBA or MTA but was lower for amalgam. There was no significant difference in healing or bone fill among irrigants at 9 or 18 days.

A comparative study on the effects of three types of laser irradiation at the apical stop and apical leakage after obturation.

OBJECTIVE: The purposes of this study were to determine the degree of apical leakage using a dye penetration method after argon, pulsed Nd:YAG with or without black ink, or Er:YAG laser treatment and obturation, and to compare the results of three types of laser irradiation in vitro. SUMMARY BACKGROUND DATA: There have been only a few reports of the laser effect on apical leakage after laser treatment and obturation. METHODS: Seventy-five human extracted single root teeth were divided into five groups of 15 teeth each and prepared up to a #60 K-file size. One group served as the control and was not irradiated. The other four groups were irradiated with an argon laser at 0.3 W for 3 seconds at continuous mode, pulsed Nd:YAG laser at 2 W and 20 Hz for 4 seconds with or without black ink, and Er:YAG laser at 50 mJ per pulse and 4 Hz for 5 seconds. In each group, ten teeth for the apical leakage study were obturated and immersed in rhodamine B solution for 48 hours at 37 degrees C, and the others were used for the observation by scanning electron microscopy (SEM). All teeth were longitudinally bisected and observed by stereoscopy or SEM. RESULTS: After pulsed Nd:YAG laser treatment with black ink and obturation, the apical leakage degree (mean score: 0) was reduced compared to that in the control (mean score: 1.2) significantly (p < 0.05). SEM findings showed that specimens irradiated by pulsed Nd:YAG laser with black ink presented clean root canal walls with debris and smear layer evaporated, melted, fused, and recrystallized in most cases. CONCLUSION: These results suggest that pulsed Nd:YAG laser irradiation with black ink at the apical stop is useful for the reduction of apical leakage after obturation.

Sealing ability of composite resin placed over calcium hydroxide and calcium sulphate plugs in the repair of furcation perforations in mandibular molars: a study in vitro.

The purpose of this study was to evaluate in vitro the sealing ability of various materials in the repair of furcation perforations in mandibular molars by measuring coronal microleakage with Indian ink. Ninety extracted mandibular molars were embedded individually into a plaster of Paris block, with the roots surrounded by a simulated periodontal ligament of silicone. Subsequently, a standard coronal access opening was prepared, the root canal orifices were located and a perforation was made with a size 012 round bur in a water-cooled high-speed handpiece directly into the centre of the floor of the pulp chamber. The perforations were repaired with amalgam, composite resin, calcium sulphate under composite resin and calcium hydroxide under composite resin. The teeth were coated with two layers of nail polish, leaving the access opening area uncovered, and immersed in Indian ink for 4 days at 37 degrees C. The teeth were sectioned longitudinally and dye penetration measured from the coronal level of the repair material to the apical end of the perforation. All experimental groups revealed dye penetration in varying degrees, but there was no significant difference amongst them (Kruskal-Wallis test P < 0.05). Calcium sulphate and calcium hydroxide prevented overextrusion of composite resin when used under this repair material.

Coronal leakage: effects of smear layer, obturation technique, and sealer.

Coronal microleakage may be a major factor in the etiology of treatment failure. This study examined the effect of obturation technique, sealer, and the presence of smear layer on coronal microleakage. Two hundred extracted human teeth were assigned to 20 treatment groups. Groups were examined with the smear layer present or smear layer removed (17% REDTA). Access cavities were exposed to artificial saliva then Pelikan Ink. Teeth were cleared and linear dye penetration measured. When all groups with the smear layer removed were compared with all groups with the smear layer present, significantly less leakage was seen when the smear layer was removed. Ultrafil displayed significantly more leakage than all other groups. Vertical compaction of lateral condensation and Thermafil obturations significantly reduced leakage. AH-26 displayed significantly less leakage than Roth's 811 sealer. These results indicate that removal of the smear layer, the use of AH-26, and vertical compactin have cumulative effects in reducing coronal leakage.

The smear layer: a phenomenon in root canal therapy.

When the root canals are instrumented during endodontic therapy, a layer of material composed of dentine, remnants of pulp tissue and odontoblastic processes, and sometimes bacteria, is always formed on the canal walls. This layer has been called the smear layer. It has an amorphous, irregular and granular appearance under the scanning electron microscope. The advantages and disadvantages of the presence of smear layer, and whether it should be removed or not from the instrumented root canals, are still controversial. It has been shown that this layer is not a complete barrier to bacteria and it delays but does not abolish the action of endodontic disinfectants. Endodontic smear layer also acts as a physical barrier interfering with adhesion and penetration of sealers into dentinal tubules. In turn, it may affect the sealing efficiency of root canal obturation. When it is not removed, the durability of the apical and coronal seal should be evaluated over a long period. If smear layer is to be removed, EDTA and NaOCl solutions have been shown to be effective, among various irrigation solutions and techniques, including ultrasonics, that have been tested. Once this layer is removed, it should be borne in mind that there is a risk of reinfecting dentinal tubules if the seal fails. Further studies are needed to establish the clinical importance of the absence or presence of smear layer.

Influence of laser enamel and dentine etching on marginal integrity of porcelain laminate veneers.

This investigation evaluated the effect of laser etching and acid etching techniques on the marginal leakage Vitadur N porcelain laminate veneers bonded either entirely on enamel, or with cervical margin located on root dentine of prepared extracted maxillary central incisors. Two different composite resin luting systems (light cured, or light and chemical cured) were used and compared. The bonded specimens were thermocycled and by employing the Standard dye penetration technique the leakage was scored from cervical and incisal margins. The least marginal leakage was observed beneath laminate veneers bonded entirely on enamel. Laser etching improved the sealing qualities of veneers with cervical margins on root dentine below the CEJ. Statistically insignificant differences were observed with the use of the two different composite resin luting systems.

Effect of different types of finishing lines and etching methods of the enamel and dentin on the marginal integrity of Hi-ceram crowns.

Porcelain is one of the oldest materials used in the dental field. It has the advantages of perfect shade reproduction, chemical and abrasion resistance and biologic compatibility to the oral tissue. The only drawback of dental compatibility to the oral tissue. The only drawback of dental porcelain is the occurrence of brittle fracture. Minute cracks formed on the outer surface of the porcelain crown are the cause of the fracture. These cracks are formed during cooling of the ceramic as a result of low thermal conductivity of the porcelain. Differential dimensional changes of the outside and the internal surface take place inducing the cracks. Tensile stresses on the internal surface of the porcelain lead to cracks propagation and fracture.