Apical leakage associated with retrofilling techniques: a dye study

The Invasion of Bacterial Biofilms into the Dentinal Tubules of Extracted Teeth Retrofilled with Fluorescently Labeled Retrograde Filling Materials

In this study, we evaluated the invasion of bacteria into the dentinal tubules of retrofilled extracted human teeth, and the influence of different fluorescently labeled retrograde filling materials on the bacterial invasion and viability, by means of confocal laser scanning microscopy (CLSM). The root apices of extracted teeth were cut, prepared, and filled retrogradely using either intermediate restorative material (IRM), mineral trioxide aggregate (MTA), or Biodentine. The roots were filled with Enterococcus faecalis bacteria from their coronal part for 21 days. Then, 3-mm-long apical segments were cut to get root axial slices, and the bacteria were fluorescently stained and evaluated by CLSM. Bacterial penetration into the dentinal tubules favored the bucco-lingual directions. The filling materials penetrated up to 957 µm into the tubuli, and the bacteria, up to 1480 µm (means: 130 and 167 μm, respectively). Biodentine fillings penetrated less and the associated bacteria penetrated deeper into the tubuli compared to MTA or IRM (p = 0.004). Deeper filling penetration was associated with shallower penetration of both dead and live, or live alone, bacteria (p = 0.015). In conclusion, the current study enables better understanding of the microbiological–pathological course after endodontic surgical procedures. It was found that even with retrograde fillings, bacteria invade deep into the dental tubules, where deeper filling penetration prevents deeper penetration of the bacteria and adversely affects the viability of the bacteria.

Clinical Evaluation of Root End Resection Bevel in Periapical Surgery

Root end resections play an important role in the success of periapical surgery. Beveling of the root end resections can vary significantly depending on the surgical technique, the root and canal morphology. The intention of this article was to clinically assess the root resections bevels and to estimate their relation to applied periapical surgeries. A prospective clinical study consisted of sixty periapical surgeries performed on teeth with chronic periapical lesions. Thirty periapical surgeries were performed in a conventional manner, while thirty were contemporary ultrasonic surgeries. Following the completion of strictly planned and performed intraoperative procedures, the resection bevels were assessed. To obtain the real bevel angles a compass was used. Root resections were significantly less beveled in all teeth operated with contemporary ultrasonic surgery, with mean values between 2.1° to 7.8°. The number of roots and their dilacerations didn't influence the root resection bevel. For comparison, root resections were significantly beveled in all conventionally operated teeth, with mean values of 46°. Due to the technical limitations of the conventional periapical surgery, mandibular premolars were exclusively operated with ultrasonic periapical surgery, with mean values of resection bevel not exceeding 20.7°. Significantly lesser resection bevel associated with ultrasonic periapical surgery contributes to root preservation and favorable surgical outcome.

Bacterial colonization in the apical part of extracted human teeth following root-end resection and filling: a confocal laser scanning microscopy study

OBJECTIVES

The purpose of this study was to evaluate Enterococcus faecalis colonization at the apical part of root canals following root-end resection and filling using confocal laser scanning microscopy (CLSM).

MATERIALS AND METHODS

The apical 3-mm root-ends of 55 extracted single rooted human teeth were resected, and 3-mm retrograde cavities were prepared and filled using either mineral trioxide aggregate (MTA), intermediate restorative material (IRM), or Biodentine (n = 10 each); 25 teeth served as controls. The roots were placed in an experimental model, sterilized, and coronally filled with E. faecalis bacterial suspension for 21 days. Then, the apical 3-mm segments were cut to get two slabs (coronal and apical). The slabs were stained using LIVE/DEAD BacLight Bacterial Viability Kit and evaluated using CLSM.

RESULTS

The fluorescence-stained areas were larger in the bucco-lingual directions compared with the mesio-distal directions (p < 0.05). The mean and maximal depths of bacterial colonization into the dentinal tubules were 755 and 1643 μm, respectively, with no differences between the root-end filling materials (p > 0.05). However, more live bacteria were found in the MTA group in comparison to IRM and Biodentine groups (p < 0.05).

CONCLUSIONS

CLSM can be used to histologically demonstrate bacterial root-end colonization following root-end filling. This colonization at the filling-dentine interfaces and deeper into the dentinal tubules may be inhomogeneous, favoring the bucco-lingual aspects of the root.

CLINICAL RELEVANCE

Following root-end resection and filling bacterial colonization may lead to inflammatory reactions at the periapical tissues; the viability of the colonized bacteria may be affected by the type of root-end filling material.

MTA apical barrier: In vitro study of the use of ultrasonic vibration

BACKGROUND

The apexification is the first alternative treatment on a permanent tooth when, after a tooth trauma and in the presence of immature apex trauma, pulp necrosis occurs. Many studies have demonstrated the efficacy of mineral trioxide aggregate (MTA) as apical sealing material of choice in these cases, but has a degree of filtration as all other materials. The objective of this study was to analyze the seal ability of MTA on the duct walls in immature teeth unirradicular apexes, using indirect vibration.

MATERIAL AND METHODS

The study was conducted on 45 teeth divided into 3 groups: Group A or control group in which no vibration for placing the MTA was used, Group B and C or groups where indirect vibration analysis was used. All samples were immersed in methylene blue to assess filtration. After performing longitudinal cuts millimetric measuring were made of the degree of filtration, divided into 3 degrees (2mm each grade filtration).

RESULTS

Results obtained confirm our hypothesis, obtaining lesser degree of filtration those groups in which indirect vibration (Groups B and C) was performed. It was shown that the degree of filtration is closely linked to the degree of adaptation.

CONCLUSIONS

MTA vibration offers better results in its adaptation to the canal walls, significantly reducing the degree of filtration.

KEY WORDS

Apexification, MTA, filtration, indirect vibration.

Morphological assessment of dentine and cementum following apicectomy with Zekrya burs and Er:YAG laser associated with direct and indirect Nd:YAG laser irradiation

OBJECTIVES

This study aimed to assess the apical surface morphology of maxillary central incisors resected 3.0 mm from the tooth apex using Zekrya burs or Er:YAG laser, with or without subsequent direct Nd:YAG laser irradiation (apical and buccal surfaces) and indirect irradiation (palatal surface).

STUDY DESIGN

Forty maxillary central incisors were instrumented and obturated. The roots were divided into 4 groups according to the root resection method (Zekrya bur or Er:YAG laser - 1.8 W, 450 mJ, 4 Hz, 113 J/cm(2)) and further surface treatment (none or Nd:YAG laser - 2.0 W, 100 mJ, 20 Hz, 124 J/cm(2)). The teeth were prepared for SEM analysis. Scores ranging from 1 to 4 were attributed to cut quality and morphological changes. The data were analyzed by the Kruskal-Wallis test and by Dunn's test.

RESULTS

SEM images showed irregular surfaces on the apical portions resected with Zekrya burs, with smear layer and grooves in the resected dentine and slight gutta-percha displacement and plasticization. On the other hand, apicectomies carried out with Er:YAG laser showed morphological changes compatible with ablated dentine, with rough surfaces and craters. In spite of the presence of plasticized gutta-percha, with the presence of bubbles, an irregular adaptation of the filling material to the root walls was also observed. Direct Nd:YAG laser irradiation of the apical and buccal surfaces of the resected roots resulted in areas of resolidification and fusion in the dentine and cementum, with a vitrified aspect; indirect Nd:YAG laser irradiation of the palatal surfaces yielded a lower number of changes in the cementum, with irregular resolidification areas.

CONCLUSIONS

There were no differences in terms of cut quality between the use of burs and Er:YAG laser or between the 2 surfaces (apical and buccal) treated with Nd:YAG laser with direct irradiation. However, morphological changes were significantly less frequent on surfaces submitted to indirect irradiation (palatal) when compared with those directly irradiated.

Dentin penetrability evaluation of three different dyes in root-end cavities filled with mineral trioxide aggregate (MTA)

The purpose of this study was to evaluate the penetration of three dyes in MTA root-end fillings. In 30 single-rooted teeth, cavities for retrofilling were prepared with an ultrasound appliance and filled with MTA. The specimens were randomly assigned to three groups (n = 10) and immersed in the following solutions: 2% methylene blue (MET), 50% silver nitrate (NIT) and 0.2% rhodamine B (ROD). Two transversal slices (1 mm) of the retrofilling region were obtained and evaluated using the Image Tool 3.0 software to obtain a quantitative evaluation (in mm²) of the dye penetration around the retrofillings. Data were submitted to statistical analysis using Student’s t-test. The lowest degree of dye penetration was observed for the NIT group, in both slices (p < 0.05). Dye penetration was significantly larger in the ROD group when compared to the NIT group, in both slices (p < 0.05), and to the MET group, only in slice 1 (p < 0.05). Within the limitations of this study, it was concluded that the choice of dye could influence the penetration evaluation in root-end filling studies, and that the NIT had the lowest penetration capacity in the apical dentine.

Scanning Electron Microscopy (SEM) and Optical Microscopy: Effects of Er:YAG and Nd:YAG Lasers on Apical Seals after Apicoectomy and Retrofill

OBJECTIVE

This study evaluated the dentinal and marginal permeability of the cut surface after apicoectomy, treatment and retrocavity preparation with Er:YAG and Nd:YAG lasers. Furthermore, scanning electron microscopy (SEM) analysed the morphological alteration of dentin caused by laser irradiation through an optical fiber.

BACKGROUND DATA

Numerous studies have shown the beneficial effects of laser treatment upon sealing dental apex, avoiding the changes of organic fluids, microorganisms and their by-products between the root canal system and periapex.

MATERIALS AND METHODS

Twenty-four extracted and endodontically treated teeth were divided into three groups: GI, apices were resected with Er:YAG laser (350 mJ; 4 Hz) treatment of cut dentinal surface and retrocavity were lased with this same laser (120 mJ; 4 Hz; bur 2051) using the optical fiber 50/10; GII, apicoectomy was performed similar to GI, however the cut dentinal surface was treated with Nd:YAG laser through optical fiber, as well as the retrocavity preparation (100 mJ; 15 Hz; 1.5 W); and GIII (control group), high speed burs were used.

RESULTS

Analysis of methylene blue dye penetration into dentin demonstrated that the specimens of the groups irradiated with laser showed to have lower infiltration indices than the control group. These results were compatible with structural and morphological injuries, evidenced by SEM.

CONCLUSION

Under the conditions of the present study, apicoectomy using Er:YAG laser, followed by dentinal surface irradiation and retrocavity preparation with Nd:YAG laser, showed to be an alternative clinical tool able to reduce the dentinal permeability.

Lasers in endodontics

With the rapid development of laser technology, new lasers with a wide range of characteristics are now available and being used in various fields of dentistry. In the past two decades, much experience and knowledge has been gained. This article provides an overview of the current and possible future clinical applications of lasers in endodontics, including their use in alleviating dentinal hypersensitivity, modification of the dentin structure, pulp diagnosis, pulp capping and pulpotomy, cleaning and shaping of the root canal system, and endodontic surgery. Endodontic procedures for which conventional treatments cannot provide comparable results or are less effective are emphasized.

Periradicular surgery of molars: a prospective clinical study with a one-year follow-up

AIM

The purpose of this prospective clinical study was to evaluate the outcome of periradicular surgery of molars after one year.

METHODOLOGY

The material consisted of 25 molars with 39 roots demonstrating periradicular lesions of endodontic origin. Surgical treatment included root-end resection, root-end preparation with sonic microtips, and root-end filling with Super-EBA cement. At the one-year follow-up examination, healing was evaluated clinically and radiographically. Healing was assigned to three categories: (i) success (ii) improvement, and (iii) failure using well defined criteria.

RESULTS

Eighty-eight per cent of the surgically treated molars showed successful healing. In 8%, the healing was rated as improved and only 4% were failures.

CONCLUSIONS

The outcome of the present study and data of recently published studies show that periradicular surgery may result in a predictable treatment outcome in molars with persistent periradicular lesions.

Effect of smear layer and direction of dentinal tubules on osteoblast adhesion to human dentin tissue

The purpose of this study was to investigate the effect of smear layer and direction of dentinal tubules on osteoblast adhesion to human dentin tissue in vitro. Dentin disks were made from human premolars extracted for orthodontic reasons. Dentin disks were cut either perpendicularly to the long axis of the tooth or at 45 degrees to the long axis of tooth. The smear layer was removed by 34% phosphoric acid gel from half of the dentin disk surface. Human osteoblast-like Saos-2 cells were grown in RPMI medium with 10% fetal bovine serum and 1% antibiotic/antimycotic cocktail under standard cell culture conditions. Cells were seeded into Nunc four-well culture plates at 1.5 x 10(5) cells per well with dentin disks in the bottom of each well. After 1 day in culture the dentin disks along with cells grown on their surface were examined with a scanning electron microscopy. Osteoblasts attached and spread on the dentin surface and formed a monolayer in the presence and absence of a smear layer. Cells spread over the dentinal tubules despite their direction. These results suggest that cell adhesion and spreading of osteoblasts is not influenced either by the existence of a smear layer or the direction of the dentinal tubules on the dentin surface.

Root-end cavity preparation after apicoectomy using a new type of sonic and diamond-surfaced retrotip: a 1-year follow-up study

PURPOSE

This study evaluated the outcome of periradicular surgery using a new set of retrotips for root-end cavity preparation.

PATIENTS AND METHODS

Forty-three patients who had 50 consecutively treated teeth with periradicular pathology were enrolled in this prospective study. After apicoectomy, root-end cavity preparation was performed, using diamond-surfaced retrotips driven by a sonic handpiece; EBA-cement was used as the root-end filling material. Healing assessment was based on clinical and radiographic criteria.

RESULTS

At the 1-year follow-up, 82% of the reexamined surgical cases presented with successful healing. Fourteen percent of the treated teeth were deemed as improved (partial healing), and 4% were classified as failures.

CONCLUSION

The new retrotips were found to be ideal for root-end cavity preparation. They simplify the surgical approach to root ends where the working space is limited by restricted access. Root-ends prepared with this new sonoabrasive technique yielded excellent results at the 1-year follow-up examination.

Considerations in the selection of a root-end filling material

Surgical root canal treatment often includes the placement of a root-end filling material. New materials have recently emerged to challenge the long-standing position of amalgam as the root-end filling material of choice. This review discusses several of the commonly used root-end filling materials, with emphasis on indications and contraindications for the use of each.

In vitro sealing ability of dentin bonding agents and cavity varnish with amalgam as retrofills

The aim of this study was to test the effect on the seal produced by an amalgam retrofill of two dentin bonding agents (Amalgambond and All-Bond) and a cavity varnish (Copalite). The three materials were tested when placed before the retrofill (group I) and before and after the retrofill (group II). Ninety teeth distributed into three groups were prepared for the retrofilling. Each group was divided into subgroups of I and II. Linear apical leakage was measured by a stereomicroscope after 1 month in dye. All materials permitted dye leakage around the retrofill, regardless of the application type. No statistical difference was found between the Amalgambond subgroups or between the All-Bond subgroups. There was less leakage in varnish group I than group II. Amalgambond group I leaked significantly less than All-Bond group I.

Ultrasonic root-end preparation: influence of cutting angle on the apical seal

Apical resection is fundamental in obtaining a correct apical seal. The purpose of this study was to evaluate how the apical root resection angle and the cavity made by ultrasonic retrotips may influence the apical seal. A total of 48 extracted teeth were endodontically treated and sealed by guttapercha vertical compaction: 24 were resected with a 45 degrees angle and 24 with a 90 degrees one. An ultrasound source (P.M. 400 EMS) and a CT5 Scaler were used to make the retrograde cavity that was filled afterwards with EBA-zinc oxide-eugenol alumina-added cement. Apical leakage was determined using fuchsin and assessed after the roots were sectioned longitudinally. Linear dye penetration in dentin and at the interface between dentin and cement was measured with a stereomicroscope (x 12 magnification), and the results were statistically analyzed. Results showed that there was less infiltration both in dentin and in the space between the filling and the dentinal wall in the group with the 90 degrees angle, but this difference was statistically significant (p < 0.0001) only for the dentin. None of the samples showed leakage greater than the depth of the preparation. An apical cavity of 3 mm or more along the vertical axis can produce a safe and effective seal.

Comparison of ultrasonic and high-speed-bur root-end preparations using bilaterally matched teeth

The purpose of this study was to compare ultrasonic and high-speed-bur root-end preparations. Seventy-six roots from 29 bilaterally matched pairs of human teeth in cadavers were used in this study. In group 1 ultrasonic preparations were made in 38 roots and filled with amalgam. In group 2 high-speed bur preparations were made in 38 roots and filled with amalgam. The size of the bony crypt was measured and the teeth were extracted and radiographed mesial-distally and buccal-lingually. None of the root-end preparations resulted in root perforation. The mean mesial-distal minimum depth of ultrasonic and high-speed bur preparations were 2.11 mm and 1.39 mm, respectively. The mean buccal-lingual minimum depth of preparation was 2.51 mm for the ultrasonic and 2.05 mm for the high-speed bur preparations. The depth of the ultrasonic preparations was significantly greater for both measurements. A significantly greater bevel angle was associated with the bur preparations, 35.1 degrees versus 16.0 degrees for the ultrasonic preparations. The incidence of ultrasonic root-end preparations deviating from the uninstrumented canal spaces was found to be 2.6%. All bur root-end preparations were at an acute angle to the long axis of the root. The bony crypt size for bur preparations was significantly greater than that for ultrasonic preparations.

Microleakage of Diaket and amalgam in root-end cavities prepared using MicroMega sonic retro-prep tips

The in vitro sealing ability of the root-canal sealer Diaket when used as a root-end filling material was compared with that of amalgam using linear micro-leakage of Indian ink. Eight groups of 20 extracted teeth each were formed, plus 12 control teeth as follows: 1) root-end resection of 45 degrees bevel, root-end cavity preparation with an 008 round bur, amalgam root-end filling; 2) 45 degrees bevel, bur, Diaket; 3) 45 degrees bevel, using a sonic retro-prep tip, amalgam; 4) 45 degrees bevel, sonic, Diaket; 5) no bevel, bur, amalgam; 6) no bevel, bur, Diaket; 7) no bevel, sonic, amalgam; 8) no bevel, sonic, Diaket. Root-end cavity depths of 3 mm were prepared. Specimens were immersed in Indian ink for 2 weeks. The teeth were demineralized, rendered transparent and linear dye penetration recorded. Results showed that Diaket provided a superior seal to amalgam irrespective of the root-end preparation. The degree of bevel of the resected root-end did not influence leakage. Sonic instrumentation resulted in a larger root-end cavity than with burs.

Root end filling materials: a review

When non-surgical attempts prove unsuccessful or are contraindicated, surgical endodontic therapy is needed to save the tooth. The procedure usually consists of exposure of the involved area, root end resection, root end preparation and insertion of a root end filling material. Numerous materials have been suggested as root end filling materials. This article is a review of the literature on the suitability of various root end filling materials based on their leakage assessment, marginal adaptation, cytotoxicity, and usage test in experimental animals and humans.

Penetration of smeared or nonsmeared dentine by Streptococcus gordonii

The purpose of this study was to investigate the penetration of smeared and nonsmeared dentine by Streptococcus gordonii. Prepared human roots, grouped as either nonsmeared or smeared, were immersed in a suspension of S. gordonii cells for 3 weeks. The roots were then prepared for scanning electron microscopy and histological analysis. Dentine discs prepared from coronal dentine were grouped similarly. Using a fluid filtration apparatus, the hydraulic conductance (Lp) of each disc was determined before and after incubation with bacterial suspension. Scanning electron microscopy evaluation of the roots following infection with bacteria showed no change in the smear layer (P < 0.0001). Histological sections revealed that bacterial penetration of all the nonsmeared samples had occurred, while nine out of 10 smeared samples showed no bacterial penetration (P < 0.0001). The Lp of the nonsmeared discs was significantly reduced by 42% (P < 0.0001) after bacterial penetration. However, the smeared samples revealed a 1% reduction in Lp which was not significant (P > 0.05). The results suggest that dentinal smear layers are an effective barrier to dentinal tubule invasion by S. gordonii.

Longitudinal evaluation of the microleakage of dentin bonding agents used to seal resected root apices

A material that bonds to dentin and seals both the root canal and exposed dentinal tubules would be desirable following root resection. The purpose of this study was to measure the sealing ability of four dentin bonding agents on the resected root end. The bonding systems evaluated were Amalgambond (AMB), Scotchbond Multi-Purpose (SMP), Prisma Universal Bond 3 (PUB 3), and All-Bond 2 (AB2). All materials were applied directly to the resected root end without a class I preparation. One-half of the roots in each group were contaminated with human blood before bonding. Microleakage was measured using fluid filtration at various time intervals from 1 to 24 wk. Results indicated that all dentin bonding agents significantly reduced apical microleakage compared with prebonded controls at all time intervals. Blood contamination did not adversely affect the sealing ability of AMB, PUB 3, or SMP. The blood-contaminated AB2 group displayed significantly greater microleakage after 12 and 24 wk than the uncontaminated roots.

Leakage of amalgam and Super-EBA root-end fillings using two preparation techniques and surgical microscopy

An in vitro dye leakage study was conducted to test the root-end sealing ability of amalgam with varnish or Super-EBA using two root-end preparation techniques and surgical microscopy. Sixty-four single-rooted teeth were instrumented and obturated with gutta-percha. Teeth were randomly placed into four groups. Two groups received perpendicular root-end resections, 3-mm-deep ultrasonic root-end preparations, and either amalgam with varnish or Super-EBA root-end fillings. The other two groups received beveled root-end resections, 3-mm-deep micro-handpiece preparations, and either amalgam with varnish or Super-EBA. All root-end procedures were performed at x5 to x8 magnification. Micro-leakage was assessed at 4 months using methylene blue dye and a passive hydrostatic pressure technique. Statistical analysis showed that, regardless of technique, Super-EBA leaked significantly less than amalgam with varnish. There was no significant difference between the two root-end resection and preparation techniques.

Effects of a carbon dioxide laser on human root dentin

The effects of the Luxar LX-20 CO2 dental laser on resected apical root dentin were examined using stereomicroscopy and scanning electron microscopy. The surfaces of 2-mm-thick sections of dentin from freshly extracted human teeth were exposed to CO2 laser radiation. Fluences used ranged from 2.1 to 625.0 J/cm2. The effects of the laser energy on the dentin ranged from no visible effects, to charring, cracking, cratering, and glazing. The most dramatic effect was cracking. Cracking was evident on all specimens having any visible modification of the dentin. A prototype-curved laser tip was used and compared with a standard straight tip. The curved tip did not deliver laser energy to the dentin as efficiently as a straight tip. CO2 laser radiation did not consistently obliterate dentin tubules.

A comparison of the apical seals achieved using retrograde amalgam fillings and the Nd:YAG laser

The purpose of this in vitro study was to compare the apical seals achieved using retrograde amalgam fillings or the Nd:YAG laser. Freshly extracted teeth were randomly separated into groups that would have their apices treated either with a Nd:YAG laser or retrograde amalgam. After instrumentation and obturation, bacterial reservoirs were prepared in the coronal portion of canals. Teeth to receive retrofillings had their apices prepared and amalgams placed. Teeth to be lasered had no apical preparations. Teeth and culture media were then sterilized by irradiation. Streptococcus salivarius was deposited in the opened bacterial reservoirs. At intervals, culture media with an indicator in culture chambers was observed for color change. Specimens that demonstrated color change were cultured for S. salivarius. Under the conditions of this in vitro study, no statistically significant difference was found in bacterial leakage between the laser-treated group and the retrograde amalgam group.

Evaluation of the bond strength of dentin bonding agents used to seal resected root apices

A number of improved dentin bonding agents have recently become available, but have not been evaluated on apical radicular dentin. The purpose of this study was to compare the tensile bond strengths of four adhesive resins on resected root ends before and after blood contamination. Forty single-rooted human incisors were cleaned and shaped and obturated. The apical 3 mm was then resected at a 45-degree angle, bonded, and tested for tensile bond strengths using an Instron machine. The bonding systems evaluated included Prisma Universal Bond 3, Scotchbond MultiPurpose Dental Adhesive, Amalgambond, and All Bond 2. All bonding systems were then covered with Prisma APH light-cure composite resin. Results indicated that the bond strengths of the blood contaminated groups were significantly less than those of the control groups, except in the case of Amalgambond where no significant difference was noted. When the surface was contaminated with blood, Prisma Universal Bond 3 had significantly lower bond strengths, whereas Amalgambond had significantly higher bond strengths than the other subgroups.

A study in vitro of threaded titanium pins used for retrograde obturation of root canals

The microleakage of four retrograde filling materials was compared in vitro. Fifty-three single rooted teeth were instrumentated and root filled with resin chloroform and gutta-percha. The gutta-percha cones were left extruding from the access opening. All teeth were apicected and retrograde fillings placed. The materials used were a non gamma 2 amalgam (Amalcap), a glass ionomer cement (ChemFil II), threaded titanium pins cemented with a glass ionomer cement (ChemFil II) and identical titanium pins cemented with a silicone material (Adheseal). After removal of the gutta-percha with tweezers, a radioactive isotope solution was placed in the teeth. Extraradicular samples were taken at 3, 7, 28, 77 and 104 days. All retrograde fillings showed some microleakage. The group with titanium pins cemented with silicone showed the least leakage: significantly less than the teeth with glass ionomer cement (P < 0.01) and with amalgam (P < 0.01). No significant differences were found between other groups.

Apical dentin permeability and microleakage associated with root end resection and retrograde filling

This study evaluated the apical leakage associated with various depths of retrograde fillings placed in root apices which had been resected at one of three different angles. Leakage was assessed with a hydraulic conductance apparatus. Teeth were divided into groups corresponding to the angle of apical resection (0, 30, and 45 degrees to the long axis of the root) and apical leakage was determined following incremental increases in the depth of the retrograde filling (Ketac Silver). Increasing the depth of the retrograde filling significantly decreased apical leakage; there was also a significant increase in leakage as the amount of bevel increased. Both the permeability of resected apical dentin and microleakage around the retrograde filling material had a significant influence on apical leakage.

Sealing ability of a mineral trioxide aggregate when used as a root end filling material

This in vitro study used rhodamine B fluorescent dye and a confocal microscope to evaluate the sealing ability of amalgam, super EBA, and a mineral trioxide aggregate when used as root end filling materials. Thirty single-canal teeth were cleaned, shaped, and obturated with gutta-percha and root canal sealer. After application of nail polish to the external surface, the apical 3 mm of each root was resected and 3-mm deep root end preparations were made. The roots were randomly divided into three groups and the root end preparations filled with the experimental materials. All roots were then exposed to an aqueous solution of rhodamine B fluorescent dye for 24 h, longitudinally sectioned, and the extent of dye penetration measured using a confocal microscope. Statistical analysis showed that the mineral trioxide aggregate leaked significantly less than amalgam and super EBA.

Sealing ability of a mineral trioxide aggregate for repair of lateral root perforations

Amalgam, IRM, and a mineral trioxide aggregate were tested for repair of experimentally created root perforations. Fifty sound, extracted mandibular and maxillary molars were used in this study. A perforation was created on the mesial root surface at about a 45-degree angle to the long axis of each tooth. The tooth was then placed into a saline-soaked "Oasis" to simulate a clinical condition. After placing the repair materials into the perforations, the teeth were kept for 4 wk in the Oasis model. The perforation sites were then stained with methylene blue for 48 h, sectioned, and examined under a dissecting microscope. The results showed that the mineral trioxide aggregate had significantly less leakage than IRM or amalgam (p < 0.05). The mineral trioxide aggregate also showed the least overfilling tendency while IRM showed the least underfilling tendency.

Management of the resected root end: a clinical review

Careful management of the resected root end during endodontic surgery is critical to the overall success of the case. After resection, the root structure presents with multiple anatomical variations and considerations at both a macroscopic and microscopic level. These include root outline, canal anatomy, dentinal tubule configuration, presence of a smear layer and root canal filling material. Proper assessment of these variables will dictate the best methods for root-end management, along with the attainment of an anatomically compatible root face for optimal healing of the periradicular tissues.

An evaluation of the effect of methylene blue dye pH on apical leakage

The effect of varying the pH of 2% methylene blue dye on apical leakage was evaluated. Eighty-four roots of extracted human teeth were used in this study. The roots were endodontically cleaned and shaped, obturated, apically resected, and amalgam or Temporary Endodontic Restorative Material retro-fillings were placed. The roots were immersed for 7 days in dye solutions of controlled pH of 1, 2, 3, 5 or 7, or in a 2% unbuffered deionized water solution of methylene blue. The results demonstrated significantly less leakage in the pH 1 and 2 amalgam groups. All other amalgam groups and the Temporary Endodontic Restorative Material groups showed no significant differences attributable to pH. Temporary Endodontic Restorative Material retrofilling groups demonstrated statistically significantly less apical leakage at each pH evaluated than the amalgam-retrofilled groups. Additionally, a significant buffering effect of the root structure on the dye solutions was measured.

Light-cured glass ionomer cement as a retrograde root seal

A light-cured ionomer cement was investigated as a retrograde root seal, without a retrograde cavity. This was compared with the material used in a retrograde cavity, and with a conventional glass ionomer cement, as a seal. The adaptation and sealing ability of the test materials were assessed using a confocal optical microscope with a fluorescent dye. The root canals of 40 extracted human single-rooted teeth were prepared and filled with gutta-percha and sealer. All the teeth were subsequently apicected, then divided into four equal groups. In one group, a retrograde cavity was prepared, and the light-cured glass ionomer cement was placed as a retrograde root filling. No retrograde cavities were prepared in the three remaining groups. The light-cured glass ionomer cement was applied directly onto the apicected root face. Two different thicknesses of light-cured glass ionomer cement were tested, a thin layer (approximately 1 mm) in one group, and a thicker layer (> 1 mm) in another group. A conventional glass ionomer cement was used in the last group, and applied directly onto the root face in a single thickness (approximately 1 mm). In the group where the light-cured glass ionomer cement was used in a retrograde cavity, the material was often well adapted to one cavity wall, but gaps were found on the opposite wall. The light-cured and conventional glass ionomer cement retrograde root seals were well adapted to the root face, regardless of the thickness of material used. The thinly applied (approximately 1 mm) light-cured glass ionomer cement retrograde root seals permitted the least leakage.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparative sealability study of different retrofilling materials

The purpose of this study was to compare the sealing ability of high-copper amalgam, glass ionomer cement, and silver glass ionomer cement as retrofilling materials when used with and without varnish. Seventy extracted human single-rooted anterior teeth were instrumented and the root canals obturated with laterally condensed gutta-percha and sealer. The apical 3 mm of each root was resected and a 2 mm-deep apical Class I preparation cut. The roots were then randomly allocated to six groups of 10 teeth and retrofilled with one of the experiment materials. Group I comprised high-copper amalgam; group 2, high-copper amalgam with cavity varnish; group 3, glass ionomer cement without varnish; group 4, glass ionomer cement with varnish; group 5, silver glass ionomer cement without varnish; and group 6, silver glass ionomer cement with varnish. Two groups of five roots each were used as positive and negative controls. The root surfaces were coated with nail polish and specimens immersed in 2% methylene blue solution for 14 days. After vertical sectioning, dye penetration was examined under a stereomicroscope. The results of the study were analysed statistically. The sealing ability of the conventional glass ionomer cement with varnish was significantly better while dye penetration was higher in silver glass ionomer cement without varnish group than the other groups (P < 0.01).

Sealing ability of cermet ionomer cement as a retrograde filling material

An in vitro dye leakage study was performed to compare the sealing ability of high copper amalgam with cavity varnish and cermet ionomer cement with and without varnish when used as retrofilling materials. The root canals of 54 maxillary anterior teeth were instrumented and obturated with gutta-percha and sealer. The apical 3 mm of the roots were resected and apical class I cavity preparations were made. The roots were then randomly divided into three groups and retrofilled with one of the experimental materials. After 72 h of immersion in India ink, the roots were cleared and evaluated for leakage with a stereomicroscope. Statistical analysis indicated that the cermet ionomer cement with varnish group had significantly less leakage than the amalgam group (P < 0.0014) and the cermet ionomer cement without varnish group (P < 0.001). There was no significant difference between the other two groups (P > 0.05).

Scanning electron microscopic study of the apical dentine surfaces lased with ND:YAG laser following apicectomy and retrofill

The purpose of this investigation was to study the effects of a Nd:YAG laser on the cut surface of teeth using scanning electron microscopy (SEM). Eighteen single-rooted teeth were cleaned, shaped, and obturated with gutta-percha and root canal sealer. The apical 3 mm of each tooth were resected with a diamond fissure bur, and the teeth were randomly divided into two groups of nine teeth each. The resected surface of each root in one group was lased twice. The duration of lasing and the number of pulses were recorded for each tooth. The teeth were air dried, mounted on stubs, sputter-coated with gold-palladium and examined under SEM. Application of the Nd:YAG laser caused melting of apical dentine surfaces. The melted material resembled the appearance of glazed interconnected droplets. Resolidification and recrystalization of the melted areas appeared to be incomplete and discontinuous. Some areas between the glazed regions appeared similar to those of non-lased apical dentine resected root surfaces.

Effects of Nd:YAG laser on apical seal of teeth after apicoectomy and retrofill

The application of Nd:YAG laser to tooth surface can change its surface permeability. The purpose of this study was to investigate the effects of Nd:YAG laser on the permeability of dentin following apicoectomy and retrofill. Sixty single-rooted teeth were randomly assigned to six groups of 10 teeth each. The six groups were arranged in three pairs, experimental and control groups. The canals of teeth in pairs 1 and 2 were cleaned, shaped, obturated, and their apical 2 mm were resected. A class I preparation was prepared and filled with amalgam in each tooth in pair 1. The apical 2 mm of each tooth in pair 3 was removed, and a class I preparation was prepared and filled with amalgam. The apical surface of resected roots in half of the samples in each pair was lased twice by using Nd:YAG laser. The duration of lasing and the number of pulses were recorded for each tooth. After application of nail polish to the unoperated surface of each tooth, the teeth were placed in 0.5% methylene blue dye for 48 h. The amount of dye penetration in sagittal sections of each tooth was measured. The amount of dye penetration was significantly lower in lased roots than in nonlased ones (p < 0.05). Based on our results, it appears that application of Nd:YAG laser reduces the permeability of resected roots.

A spectrophotometric analysis of dentinal leakage in the resected root

The purpose of this study was to compare dye leakage in the dentin of resected and nonresected roots. Fifty-four single rooted extracted teeth were used. The two groups were subdivided into young, middle age, and old age samples. Each sample was biomechanically prepared in a standard fashion and obturated using lateral condensation with sealer and gutta-percha. All root surfaces were sealed with nail polish, leaving the apical portion exposed. The apical portion of the roots were placed in 2% methylene blue dye for 72 h, rinsed, and placed in 15 ml of 35% HNO3 for 72 h. The supernatant was analyzed at 640 nm using a visible light spectrophotometer. The amount of leakage was extrapolated from a standard linear regression curve constructed from the stock 2% methylene blue dye solution. The percentage of concentration leakage in all samples ranged from less than 0.0600 to 0.1658. It was concluded that there is a greater amount of leakage in resected versus nonresected extracted teeth. The data also suggest that older teeth exhibit less leakage than younger teeth.

Intracoronal isolating barriers: effect of location on root leakage and effectiveness of bleaching agents

The purpose of this study was to evaluate the ability of several intracoronal isolating barrier materials to prevent leakage of a bleaching agent into the roots of teeth and to determine whether placement of the barrier material at the cementoenamel junction or below the cementoenamel junction has an effect on the bleaching results of the crowns. Fifty teeth were stained in vitro, and gutta-percha fillings were placed in the root canals. The experimental isolating barriers were placed at the cementoenamel junction or 2 mm below the cementoenamel junction. A walking bleach of Superoxol and sodium perborate was placed in the pulp chamber for three treatments. The roots of the teeth were evaluated for the presence of root decoloration, and the crowns of the teeth were evaluated for bleaching effect. Findings from this study showed a significant difference between gutta-percha alone and gutta-percha with barrier in preventing root decoloration (p less than 0.05). No significant differences were found between the other experimental groups in preventing root decoloration. Placement of an intracoronal isolating barrier material 2 mm below the cementoenamel junction resulted in a more acceptable esthetic bleaching result of the crowns than did placement of barrier material at the cementoenamel junction.

Retrograde approaches in endodontic therapy

The routine use of retrograde fillings during apical surgery, as well as the material of choice for that purpose, have been debated. A retrograde filling is placed so as to seal an infected root canal causing periapical pathosis. Therefore, retrograde root canal fillings should be performed routinely during apical surgery regardless of the apparent technical quality of the root canal obturation, unless orthograde endodontic treatment is performed in conjunction with surgery. When orthograde treatment is not performed, retrograde root canal filling enhances the prognosis of apical surgery. An array of potential retrograde filling materials have been extensively investigated in vitro and in vivo. Once that the biocompatibility of the materials is confirmed a clinical comparison, rather than in vitro sealability studies, is the most valid evaluation method. Some of the difficulties encountered in long term clinical studies in patients may be avoided in animal studies. The review of the relevant literature of the past decade suggests that amalgam used in conjunction with cavity varnish is the retrograde filling material of choice. It must be stressed, however, that retrograde filling is not comparable to debridement and obturation of the entire root canal. Therefore, when the only way to approach the root canal is from the apical direction, rather than placing an apical retrograde filling, a retrograde endodontic treatment of the entire canal should be preferred, if it is feasible.

Microleakage associated with retrofilling of the apical two thirds with amalgam

In this investigation the effect of increasing the thickness of amalgam retrofilling on its sealing ability was studied and compared with the sealing ability of the laterally condensed gutta-percha with a sealer. The apical two thirds of the canals of 118 upper central incisors, filled with laterally condensed gutta-percha, were sealed with amalgam. Amalgam retrofills were also used to seal the apices of the roots of six teeth that had no other filling in their canals. The effectiveness of both techniques was determined by their ability to inhibit the penetration of methylene blue dye for the periods of 24 hours, 1 week, and 1, 3, and 6 months. At 24 hours both materials showed comparable sealing ability. However, the sealing ability of laterally condensed gutta-percha was significantly better than that of amalgam from the 1-week period until the end of the study. The depth of marginal penetration around both materials increased with time. The amount of the dye penetration increased acutely around amalgam, whereas its increase around gutta-percha was more uniform. At the end of the study, specimens retrofilled with amalgam exhibited total dye penetration that exceeded the full thickness of amalgam (6 mm) and spread into the root canal space. On the other hand, the mean value for marginal penetration of the dye around the laterally condensed gutta-percha was 2.6 mm at the end of the study. The present investigation proved beyond doubt that the use of any thickness of retrograde amalgam to seal the apex, with no other filling within the canal, invites failure.

Longitudinal evaluation of the seal of endodontic retrofillings

The apical seal obtained with various retrofilling materials placed in prepared, extracted human anterior teeth was measured at various time intervals. Materials evaluated were cold-burnished gutta-percha, amalgam, amalgam with a cavity varnish, SuperEBA cement, and a glass ionomer restorative material (Ketac-Silver). Control groups included teeth retrofilled with either gutta-percha without sealer or TERM. The root canals were cleaned and shaped and the root ends were prepared for retrofilling. The materials were placed into the preparations and allowed to set for 24 h. Microleakage was measured at 24 h, 1, 2, and 3 wk, and 1, 2, and 3 months after insertion of the retrofilling using a fluid filtration technique. Multiple range analysis indicated that Ketac-Silver produced a significantly inferior seal when compared with the other materials at all time periods. There was no significant difference among SuperEBA, amalgam, and amalgam with a cavity varnish.

Sealing ability of materials used as retrograde root fillings in endodontic surgery

The sealing ability of retrograde root fillings of amalgam plus cavity varnish, EBA cement, glass ionomer cement, light-cured composite resin, dentine bonding agent, and light-cured composite resin plus dentine bonding agent were compared with laterally condensed conventional root fillings. A dye penetration technique was used to assess microleakage and it was concluded that none of the materials produced a perfect seal but that glass ionomer cement, light-cured composite resin, light-cured composite resin plus dentine bonding agent and dentine bonding agent alone produced better seals than conventional laterally condensed gutta-percha, amalgam plus cavity varnish and EBA cement.

Apical sealing efficacy of two reverse filling techniques versus cold-burnished Gutta-percha

The apical seal produced by the cold-burnished gutta-percha method and two amalgam reverse filling techniques was investigated in an in vitro study using 36 extracted human single-rooted teeth. Following root canal obturation, 27 teeth were divided into three experimental groups and each group was subjected to one of the three following filling techniques: (a) cold-burnishing of gutta-percha; (b) amalgam reverse filling; and (c) amalgam reverse filling in conjunction with cavity varnish. The remaining nine teeth served as controls (4). The teeth were placed in methylene blue dye for a period of 1 wk, after which they were retrieved, washed, sectioned, and the apical dye penetration measured. The results showed that amalgam with cavity varnish demonstrated less dye penetration than the other experimental groups. The difference was statistically significant (p less than 0.0001).

Dentinal tubules at the root ends of apicected teeth: a scanning electron microscopic study

Two groups of teeth, one of which contained teeth of known age, were examined by scanning electron microscopy to ascertain the presence of a potential pathway for leakage at the root ends of apicected teeth. At a point approximately 3 mm from the apex, a level chosen as being typical for apicectomy, and half-way between the root canal and the dentine-cementum junction, there were found to be, on average, 27,000 tubules per mm2. Older teeth also displayed large numbers of tubules. Close to the dentine-cementum junction, an area which may communicate with the root canal even in the presence of a retrograde root filling, an average of 13,000 tubules per mm2 were found.