The quality of root fillings remaining in mandibular incisors after root-end cavity preparation

AIM: The aim of this study was to determine the quality of root fillings remaining in mandibular incisors after root-end resection and root-end cavity preparation. METHODOLOGY: Roots of 40 mandibular incisors,12 mm in length, were divided into two groups and instrumented using a balanced force technique and obturated by vertically compacted warm gutta-percha. In one group sealer was used when back-filling the root canal with the Obtura System. The other group was also back-filled with the Obtura System but without sealer. The apical 4 mm of each root filling was removed by root-end resection and root-end cavity preparation. Fluid transport along the 7 mm of remaining root filling was measured. After the leakage test, horizontal sections were cut at a level 3 mm from the apical end of the remaining root filling. The cross sectional area of the canal and gutta-percha was measured using an image analysis program. The quality of the remaining root fillings was also evaluated by calculating the percentage of gutta-percha filled canal area. RESULTS: In total, 27 (67%) out of the 40 roots demonstrated leakage. No significant difference was found between the two groups (P = 0.265). In the cross-sections the bucco-lingual canal diameter was up to 2.6 mm long (mean 1.6 mm). The average percentage of gutta-percha filled canal area was 85.6%. Warm gutta-percha could not obturate areas where debris remained after instrumentation. CONCLUSIONS: The quality of the root fillings in mandibular incisors was poor, probably because the unprepared recesses of oval canals were not clean.     

Effect of root-end resection and root-end filling on apical leakage in the presence of core-carrier root canal obturation

AIM: To evaluate the apical seal of canals filled with a core-carrier obturator following root-end resection with and without a root-end filling. METHODOLOGY: Thirty single-rooted human teeth with single canals were used. Root canal treatment was performed and canals filled with a core-carrier obturation technique. The teeth were then randomly assigned to three groups (n = 10). In the first group root canal filling only was performed. After orthograde filling, the teeth of the second group were resected apically, perpendicular to the major axis of the root. In the third group after apical resection, a root-end cavity was prepared using ultrasonic diamond retrotips and the cavities filled with Super-EBA cement. During a period of 3 h and with a headspace pressure of 0.12 atm, methylene-blue solution was forced through a tube that was connected to the apical end of each tooth specimen. The coronal end of the tooth was connected to a capillary tube containing an air bubble. Leakage was evaluated by observing the distal displacement of the air bubble. The roots were then sectioned along their long axis. Using a stereomicroscope, linear dye infiltration at the dentine-cement interface was determined. Kruskal-Wallis and Mann-Whitney tests were used to compare the three groups. RESULTS: Linear dye infiltration was significantly greater in root canals filled with the core-carrier obturators and resected apically (0.9 +/- 0.9 mm) when compared with those that had root-end fillings (0.2 +/- 0.4 mm). Air bubble displacement was not observed. CONCLUSION: Root-end filling improves the sealing of roots with core-carrier obturation following root-end resection.     

Ultrasonic root-end preparation Part 2, Microleakage of EBA root-end fillings

The effect of three methods of root-end preparation, following apical resection, on the apical seal of root-end fillings, was studied in vitro. Root canals of 116 single-rooted teeth with mature apices were prepared chemo-mechanically and obturated with gutta-percha and sealer. The root ends were resected with a diamond bur under water coolant and were prepared as follows: group I a size 010 round bur was used to prepare an apical cavity 2–3 mm down the long axis of the root; group II treatment as per group 1 followed by a 60-s rinse with a solution of 10:3 (10% citric acid: 3% Fe₂Cl₃); and group HI an ultrasonic retrotip was used to prepare a 2–3 mm deep apical cavity. The root end was restored with an EBA cement. Apical leakage was determined using India ink after 7 days and 7 months. The teeth were demineralized, rendered transparent and linear dye penetration was recorded. Results showed that there was no significant difference in leakage between the groups at each time interval (P>0.05) but there was increased leakage after 7 months (P<0.01). Cracking of the root surface was seen most often with the ultrasonically prepared roots (P<0.001).     

Polymicrobial coronal leakage of super EBA root-end fillings following two methods of root-end preparation

The aim of this study was to compose in vitro coronal leakage of a super EBA root-end filling material after two root-end cavity preparation techniques. A mixed anaerobic microbial marker was used. Forty-five extracted human teeth with straight, single root canals were prepared chemo-mechanically to a size 40 master apical file. The teeth were divided into experimental groups (35 teeth) and control groups (10 teeth). Forty teeth (35 experimental teeth and five negative control teeth) were obturated by lateral condensation of cold gutta-percha with Tubliseal EWT sealer. The remaining five teeth were not obturated and served as positive controls. These teeth were stored for 6 months in artificial saliva. The apical 3-4 mm of each root was resected perpendicular to the long axis of the root and a root-end cavity prepared to a depth of 3 mm using either a size 008 rosehead burr or an ultrasonic retroprep tip. Freshly mixed EBA cement was placed into the root-end cavity. The entire root surface of each tooth, except the cutting surface of the apical end, was sealed with nail varnish. The coronal part of each root canal was sealed with the cut end of a tube and placed in a bottle containing sterile Brain Heart Infusion Broth (BHIB). A marker consisting of Anaerobic streptococci and Fusobacterium nucleatum in BHIB was placed in each coronal chamber at 7-day intervals and daily observations were made for bacterial growth in the apical chamber for 60 days. All positive control teeth exhibited bacterial leakage within 48 h, whilst the apical chamber of negative control teeth remained uncontaminated throughout the test period. Fifty-nine percent ( n = 10) of the specimens prepared with a burr showed leakage after 90 days, whilst only 22% ( n = 4) of the ultrasonically prepared group showed leakage after the same time. The group prepared with ultrasonic tips showed statistically significant less specimens with leakage ( P < 0.05) than the group prepared with burrs.     

Ex vivo microscopic assessment of factors affecting the quality of apical seal created by root-end fillings

AIM: (i) To evaluate the incidence of microcracks around root-end preparations completed with ultrasonic tips and their relationship with the root filling technique and thickness of surrounding dentine. (ii) To investigate the effect of rapid exposure to a water-soluble dye of Intermediate Restorative Material (IRM), Super Ethoxybenzoic Acid (sEBA) and Mineral Trioxide Aggregate (MTA), on the marginal adaptation and microleakage of root-end fillings. (iii) To describe the microstructure of the surface of root-end filling materials. METHODOLOGY: Ninety-two single-rooted teeth were divided into two groups (n = 46) according to the root canal instrumentation/filling techniques. Group 1 consisted of specimens in which canal preparation was completed using a crown-down technique and then filled with the Thermafil system (TF group); Group 2 consisted of specimens in which canal preparation was completed using a step-back technique and lateral condensation (LC group). Following root-end resection and ultrasonic cavity preparation, the samples were further divided into three subgroups (n = 24) for root-end filling with IRM, sEBA or MTA. The ultrasonic preparation time was recorded. Eight teeth were kept as positive and 12 as negative controls. Following immersion in Indian ink for 7 days, all resected root surfaces were evaluated for the presence of microcracks and the cross-sectional area of root-end surface and root-end filling were measured to evaluate the thickness of the dentinal walls. Thereafter, the samples were sectioned longitudinally so as to assess the depth of dye penetration and marginal adaptation of root-end fillings. Negative controls longitudinally sectioned were used to describe microstructural characteristics of the root-end filling materials using scanning electron microscopic (SEM) techniques. RESULTS: Although the thickness of dentinal walls between groups 1 and 2 was similar, the ultrasonic preparation time and number of microcracks were significantly higher (P < 0.001) in the TF group. Both groups had a significant correlation between microcracks and ultrasonic preparation time (P < 0.001). sEBA and IRM had better adaptation and less leakage compared with MTA. A SEM analysis displayed microstructural differences between the root-end filling materials. CONCLUSION: Microcracks can occur independently of the thickness of dentinal walls and may be associated with the prolonged ultrasonic preparation time required for the removal of the root filling during root-end cavity preparation. Although sEBA and IRM had better behaviour than MTA regarding microleakage and marginal adaptation, it is possible that exposure of MTA to a water-soluble dye before achieving full set and its porous microstructure contributed to the results.     

Apical microleakage of root-end cavities prepared by CO2 laser

This in vitro study in extracted human teeth was designed to compare the degree of dye penetration of root-end cavities prepared by CO2 laser, ultrasonic retrotip, or rotary instrument. Eighty-two human anterior teeth were prepared and obturated with laterally condensed gutta-percha and sealer. Root-end resection was performed at 90 degrees, 3 mm from apex. Root-end cavities were prepared by CO2 laser beam, ultrasonic retrotips, or bur and were filled with amalgam. The teeth were isolated and immersed in basic fuchsin at 36 degrees C for 48 hours. The roots were split longitudinally and examined by a stereomicroscope. Leakage was quantified by linear measurement of dye penetration with the aid of image-analyzing software. Apical leakage in the CO2 laser group was significantly less than in the ultrasonic retrotip and bur groups. The difference between the ultrasonic and bur groups was insignificant. Based on the results of this in vitro study, application of CO2 laser for root-end cavity preparation appears to decrease the apical leakage.     

根管截面形态对超声根尖倒预备效果的影响

目的 研究不同根管截面形态(椭网形和圆形)对超声根尖倒预备效果的影响.方法 选取直的单根管离体牙,根据根管截面形态分为椭圆形根管组和网形根管组,每组各20颗,分别进行根管预备和充填,截去根尖3 mm.采用超声工作尖进行根尖倒预备,在体式显微镜和扫描电镜下观测根尖窝洞形态规则性、残余牙胶量和窝洞清洁程度.结果 体式显微镜观测结果显示两组根尖窝洞形态规则性差异有统计学意义(P<0.01),椭圆形组中所有样本均可见牙胶残余,圆形组中70%的样本无牙胶残余,超声倒预备后残余牙胶量椭圆形根管组高于圆形根管组(P<0.01);电镜观测结果显示,圆形组85%的样本存在玷污层,95%的样本可见开放牙本质小管;椭圆形组中所有样本均有玷污层存在,仅40%的样本可见开放牙本质小管,根尖窝洞清洁程度椭圆形根管组低于圆形根管组(P<0.01).结论 超声根尖倒预备难以完全去除玷污层,椭圆形根管倒预备效果比圆形根管差.     

Periapical healing of mandibular molars after root-end sealing with dentine-bonded composite

AIM: The purpose was to present the frequency of periapical healing in first and second/third mandibular molars, after root-end resections sealed with a dentine-bonded resin composite. METHODOLOGY: Root-end sealing of resected mandibular molar roots was made with dentine-bonded composite (Gluma-Retroplast) as a cover on the entire slightly hollowed root-end, in an attempt to prevent leakage. RESULTS: Out of the 834 roots recalled between 6 months and 12.5 years postoperatively, 92% showed complete apical healing, 1% uncertain healing and 7% exhibited failure. The healing result of 681 first molar roots was not significantly different (P = 0.21) from that of 153 second/third molar roots, and there was no significant difference in healing between mesial and distal roots (P = 0.32 for first molars, P = 0.86 for second/third molars) or amongst six age groups (P = 0.94). In the patient group: 71-89 years, 36 roots showed an average of 97% with complete healing. Out of 25 failures who were retreated surgically, 80% showed complete healing when examined subsequently. CONCLUSION: Root-end sealing of mandibular molars with dentine-bonded resin composite is a promising technique giving 92% complete healing in cases examined between 6 months and 12 years postoperatively.     

Investigation of the marginal adaptation of root-end filling materials in root-end cavities prepared with ultrasonic tips

AIM: To compare the surface topography of root apices following ultrasonic root-end preparation, and again after root-end fillings submitted to three different finishing techniques. METHODOLOGY: Eighty-one root-end cavities prepared ultrasonically in human canines, were divided at random into three test groups of 27 each. The cavities were filled with Super-EBA, IRM, or ProRoot-MTA and finished by ball burnishing. Eighteen roots from each group received a final finish with either a 30-fluted tungsten carbide finishing bur, or a Zekrya carbide 28 mm bur after storage in water at 37 degrees C for 24 h. The root-end surface topographies were reproduced by means of polyvinylsiloxane impressions and epoxy resin replicas. Scanning electron micrography (SEM) images of each replica were taken prior to and after root-end filling. An image analysis system was used to compare the alteration of the marginal chipping areas and to calculate the gaps located in the dentine/root-end filling interface. RESULTS: When a bur was used to finish the set materials, a significant (P < 0.05) area of marginal chipping was eliminated. The finishing technique did not significantly (P > 0.05) affect the incidence of gaps in groups root-end filled with MTA or IRM. Super-EBA and IRM retrofillings finished with a ball burnisher or a Zekrya bur displayed a significantly (P < 0.05) larger calculated gap area than roots filled with MTA. CONCLUSION: Under this in vitro study, the marginal adaptation of MTA was good with or without finishing procedures. Applying a finishing bur over the condensed and set IRM and Super-EBA created better marginal adaptation.     

Effects of ultrasonic root-end preparation on microcrack formation and leakage

Root-end preparations made with conventional ultrasonic (CUS) tips, diamond-coated ultrasonic (DUS) tips, and high-speed stainless-steel burs (HSB) were compared for the incidence of microcracks and dye leakage. One hundred twenty incisors were instrumented, obturated, and had 3 mm resected from their apices. Sixty teeth were used for microcrack evaluation before and after root-end preparation with CUS, DUS, or HSB. Three types of microcracks were observed: intracanal, extracanal, and communicating. Four of the five cracks observed after root resection (before root-end preparation) were of the extracanal or intracanal type. After root-end preparation, 19 of the 41 new microcracks that developed were the communicating type. There was no significant difference among CUS, DUS, or HSB for the number or type of cracks. Of the remaining 60 resected teeth, 25 were prepared with DUS, 25 with CUS, and 10 served as controls. All of the DUS and CUS teeth were filled with Super-EBA. Dye penetration was measured after immersion in Pelikan ink for 5 days. The dye penetration difference between DUS and CUS was not significant.     

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 microleakage of Indian ink. Eight groups of 20 extracted teeth each were formed, plus 12 control teeth as follows: 1) root-end resection of 45° bevel, root-end cavity preparation with an 008 round bur, amalgam root-end filling; 2) 45° bevel, bur, Diaket; 3) 45° bevel, using a sonic retro-prep tip, amalgam; 4) 45° 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.     

Marginal adaptation of mineral trioxide aggregate (MTA) compared with amalgam as a root-end filling material: a low-vacuum (LV) versus high-vacuum (HV) SEM study

AIM: To compare the marginal adaptation of mineral trioxide aggregate (MTA) or amalgam root-end fillings in extracted teeth under low-vacuum (LV) versus high-vacuum (HV) scanning electron microscope (SEM) viewing conditions. METHODOLOGY: Root-end fillings were placed in 20 extracted single-rooted maxillary teeth. Ten root ends were filled with MTA and the other 10 root ends were filled with amalgam. Two 1 mm thick transverse sections of each root-end filling were cut 0.50 mm (top) and 1.50 mm (bottom) from the apex. Gap size was recorded at eight fixed points along the dentine-filling material interface on each section when uncoated wet (LV wet (LVW)) and dry under LV (0.3 Torr) in a JEOL JSM-5800 SEM and backscatter emission (LV dry uncoated (LVDU)). The sections were then air-dried, gold-coated and gap size was recorded once again at the fixed points under HV (10(-6) Torr; HV dry coated (HVDC)). Specimen cracking, and the size and extent of the crack were noted. RESULTS: Gap sizes at fixed points were smallest under LVW and largest under HVDC SEM conditions. Gaps were smallest in MTA root-end fillings. A General Linear Models Analysis, with gap size as the dependent variable, showed significant effects for extent of crack in dentine, material and viewing condition (P = 0.0001). CONCLUSIONS: This study showed that MTA produced a superior marginal adaptation to amalgam, and that LVW conditions showed the lowest gap size. Gap size was influenced by the method of SEM viewing. If only HV SEM viewing conditions are used for MTA and amalgam root-end fillings, a correction factor of 3.5 and 2.2, respectively, may be used to enable relative comparisons of gap size to LVW conditions.     

Comparison of Diaket and MTA when used as root-end filling materials to support regeneration of the periradicular tissues

AIM: The objective of this study was to evaluate on a comparative basis the potential for mineral trioxide aggregate (MTA) and Diaket to promote periradicular tissue regeneration when used as surgical root-end filling materials. METHODOLOGY: Seven dogs weighing between 15 and 25 kg were anesthetized prior to having the root canals of their mandibular premolars accessed, cleaned, shaped and obturated. Coronal access cavities were restored with IRM. Surgical access to the root ends was established and the root ends were resected and prepared with ultrasonic tips. Root-end fillings of either MTA or thickly mixed Diaket were randomly assigned to the preparations. Reflected tissues were repositioned and sutured with 4-0 vicryl sutures. Sixty days postsurgery, the animals were killed, perfused with 10% neutral buffered formalin and the third and fourth premolars removed in block sections. The specimens were demineralized and sectioned at 6-microm intervals for histological assessment. Sections were stained with either haematoxylin and eosin or Gomori's one step trichrome stain and examined under the light microscope. All evaluations were made by two calibrated examiners and gradings were scored based on established criteria. The raw data was evaluated statistically using anova after adjusting for the animal block effect. RESULTS: Statistical evaluation indicated that there were no statistical differences between the observed regenerative responses of the tissues to the two root-end filling materials. CONCLUSIONS: Both Diaket and MTA can support almost complete regeneration of the periradicular periodontium when used as root-end filling materials in periradicular surgery on noninfected teeth.     

Evaluation of root-end cavity preparation using ultrasonic retrotips

AIM: To evaluate and compare the efficiency of root-end preparations using ultrasonic retrotips coated with diamond and zirconium nitride. METHODOLOGY: Eighty-five extracted single-rooted teeth were root filled, and then resected 3 mm from their apices. Root-end cavities were prepared with KiS (zirconium nitride-coated retrotip), CT-5 (stainless steel tip) or diamond-coated (DC) ultrasonic retrotips, and 10 teeth served as controls. Thirty teeth were used for evaluation of the time required to prepare the root-end cavity, the number of microcracks produced on the resected surface and the number of dentinal tubule openings on the root-canal wall using scanning electron microscope (SEM) images. A further 55 teeth were used for evaluation of dye penetration following filling of the root-end cavities with Super EBA. The degree of dye penetration in millimetres was measured under the microscope after 7 days of immersion in India ink. Statistical analyses were performed using the one-way ANOVA and Scheffe's F-test as the post hoc test. RESULTS: There was no significant difference in the number of microcracks and dentinal tubule openings present in the root apices prepared by the three retrotips. The time required for root-end cavity preparation using the DC retrotip was significantly less than that using the other groups (P<0.01). Positive controls showed dye penetration throughout the length of the root-end cavity, and negative controls showed no dye penetration. There was no significant difference between the three experimental groups in dye penetration. CONCLUSIONS: In this laboratory study, the time required to prepare root-end cavities using KiS retrotips was the same as that using CT-5 retrotips, and longer than that using DC retrotips. There was no significant difference in the number of microcracks or dye penetration between the three kinds of retrotips.     

A comparison of MTA, Super-EBA, composite and amalgam as root-end filling materials using a bacterial microleakage model

AIM: The aim of this study was to compare traditional and newly developed root-end filling materials for resistance to bacterial microleakage. METHODOLOGY: Sixty extracted single-rooted teeth were randomly divided into five groups for root-end filling with mineral trioxide aggregate, Super-EBA, TPH composite resin with ProBond dentine bonding agent, Dispersalloy amalgam with and without ProBond, and positive and negative control groups. Root canals were instrumented using the step-back technique and simulated root-end resections performed. Root-end filling materials were placed in 3 mm ultrasonic retropreparations. Nail varnish was applied to all external root surfaces to the level of the resected root ends to prevent lateral microleakage. Samples were sterilized in an ethylene oxide sterilizer for 12 h. Using a newly designed model system, the apical 3-4 mm of the roots were immersed in BHI culture medium with phenol red indicator within culture chambers. The coronal access of each specimen was inoculated every 48 h with a suspension of Streptococcus salivarius. Culture media were observed every 24 h for colour change indicating bacterial contamination. Media demonstrating colour change were plated for S. salivarius. Samples were observed for 12 weeks. RESULTS: At 4 weeks 10% of specimens from each experimental group had evidence of leakage. At 8 weeks 20% of specimens filled with amalgam without dentine bonding agent, Super-EBA and MTA had evidence of leakage. At 12 weeks minor differences between materials were noted. CONCLUSIONS: Under the conditions of the study, despite some variations, there were no statistically significant differences in rate of microleakage among the five groups tested at either 4, 8 or 12 weeks.     

Ultrasonic preparation and obturation of root-end cavities

This study evaluated the preparation of root-end cavities using an ultrasonically activated file, and the obturation of such cavities. In the first part, the root canals of 40 extracted teeth were prepared to size 40 and irrigated with NaOCl and EDTA. The root ends were resected and the teeth inoculated with Enterococcus faecalis, incubated for 10 days and divided into four groups: control; saline irrigation; hand instrumentation performed via a retrograde approach up to size 50 using saline irrigant; ultrasonic instrumentation with prebent size 40 K-flex file inserted into a Piezon Master using saline irrigant. The teeth were fixed, sectioned longitudinally and viewed under scanning electron microscopy. Bacterial and smear layer scores were obtained at 1, 3, and 5 mm from the resected end. The bacterial scores for control and saline groups were similar; the scores for each instrumentation group were significantly lower than the control group (P<0.001), In addition, there were significantly fewer bacteria in the ultrasonic group compared with the hand instrument group (P<0.001), The smear layer scores for control and saline groups were similar, and significantly lower than in either instrumentation group (P<0.001). In the second part, root-end cavities were ultrasonically prepared in 20 extracted teeth. Ten cavities were filled with amalgam, and 10 with thermoplasticized gutta-percha and Grossman s sealer. After 24-h storage, the root ends were immersed in dye for 48 h. Cross-sectional slices of the obturated part of the root were evaluated using both light and confocal microscopy for dye leakage along the interface of filling material and dentine. There were no statistical differences between the leakage of amalgam and gutta-percha root-end fillings, nor between the two methods of microscopy.     

Confocal microscopy: A valid approach to evaluate the three-dimensional characteristics of root-end cavities

Objective: To analyze, using confocal microscope, the three-dimensional characteristics of the root-end cavity preparations completed in root apices of extracted teeth determining their area, perimeter, circularity and cavo-surface angle. Study design: Thirty-two single-rooted extracted teeth underwent endodontic treatment and apical resection. Root-end cavities were prepared according to 4 protocols, as follows: Group1, stainless steel ultrasonic tips (SST) at 33 KHz power; Group 2, SST at 30 KHz power; Group 3, diamond-coated ultrasonic tips (DCT) at 30 KHz power; and Group 4, DCT at 33 KHz power. Finally, root-end cavity was evaluated using a confocal microscope, recording its area, perimeter, circularity and cavo-surface angle. Results: The largest cavity perimeter was found in the Group 2 (4.8 ± 1.6 mm) (p & 0.05). Root-end cavities performed using SST showed larger areas than those performed with DCT (p = 0.03). The power of vibration or the tip type did not show correlation with the perimeter, circularity and cavo-surface angle of the root-end cavity (p & 0.05). Conclusions: Confocal microscopy is a useful approach to study the three-dimensional characteristics of the root-end cavity. Key words:Confocal microscopy, root-end cavity, surgical root canal treatment, ultrasonic tips.     

Root-end cavity preparation using the MicroMega Sonic Retro-prep Tip™. SEM analysis

The objective of this laboratory study was to compare root-end cavities prepared with sonic Retro-prep tips in a MM 1500 Sonic Air handpiece with those created by burs in a conventional handpiece. A total of 80 single-rooted extracted human teeth with mature apices and straight canals were included in the study. Four groups of 20 extracted teeth were prepared as follows: I, a 3-4 mm root-end resection perpendicular to the long axis of the root, with a size 40 sonic Retro-prep tip creating an apical cavity 3 mm into root canal system; II, a 45° bevel of the root-face removing a 3-4 mm root segment and root-end preparation as per group I; III, root-end resection as per group I, with an apical cavity prepared using a size 010 inverted cone bur 3 mm down the long axis of the root; IV, resection as per group II, followed by an apical cavity preparation with a size 010 inverted cone bur 3 mm into the root canal system. The apical root portion and root-end cavities were replicated and prepared for SEM analysis at × 20 and × 80 magnification. The degree of chipping associated with the margin of the root-end cavities, as evaluated with a standard grading system, and the incidence of root-face cracks were noted. Marginal chipping of root-end cavities prepared using sonic instrumentation was significantly worse than that produced by burs (P<0.001). Perpendicular root-end resections showed significantly better scores than bevelled root-end resections (P<0.005). The incidence of root-face cracking was low with no significant difference between the experimental groups.     

Periradicular healing in response to Diaket root-end filling material with and without tricalcium phosphate

The healing of the periradicular tissues was evaluated when the polyvinyl resin Diaket with and without tricalcium phosphate was used as surgical root-end filling material. Non-surgical root canal treatment was performed on 56 mandibular premolar roots in mongrel dogs. Following root-end resection, root-end cavity preparations were filled with Diaket, the comparative material, or Diaket in combination with tricalcium phosphate, the experimental material. Postsurgically, healing of the tissues adjacent to the filling materials and in the surrounding surgical site were evaluated at 30 and 60 days. There was virtually no statistically significant difference between the experimental and comparative group at or within the 30- or 60-day period with regard to inflammation, connective tissue formation, root-end encapsulation, cementum formation, or bone apposition. Findings suggest that cementogenesis occurred over both materials. The overall healing of the periradicular tissues was favourable.     

Analysis of the healing response to gutta-percha and Diaket when used as root-end filling materials in periradicular surgery

AIM: To analyse the healing response to gutta-percha and Diaket when used as root-end filling materials in periradicular surgery. METHODOLOGY: Periradicular surgery was completed using the mandibular second, third and fourth premolar teeth from nine male mongrel dogs. The six roots on one side of the mouth were randomly allocated to one of the following groups: group A: a resected root end and a burnished gutta-percha root filling; group B: cavities were prepared to a depth of 4.0 mm, using ultrasonic root-end preparation and filled with Diaket. The response was evaluated histologically at 55 (nine specimens) and 150 (three specimens) days post operatively. RESULTS: The data for the 55-day period was analysed statistically using Wilcoxon's Signed Ranks test. No statistical analysis was carried out on the 150-day group due to the small number of specimens. The level of significance was set at P < 0.05. No statistical significance was observed in the healing response between Diaket and gutta-percha in the following categories at 55 days: inflammatory response, angiogenesis, root-end resorption, and cementum deposition. Statistically significant differences were observed in the healing categories: bone apposition (P < 0.05) and periodontal ligament formation (P < 0.05). CONCLUSIONS: At both time intervals, Diaket had a better healing response that was characterized by hard tissue formation adjacent to the root-end filling material bordered by occasional multinucleated giant cells. The nature of both the hard tissue formation and the adjacent cells, however, remains undetermined. Diaket displayed the best healing of either material used in this study.