Angiogenesis and the prevention of alveolar osteitis: a review study

Angiogenesis is one of the essential processes that occur during wound healing. It is responsible for providing immunity as well as the regenerative cells, nutrition, and oxygen needed for the healing of the alveolar socket following tooth extraction. The inappropriate removal of formed blood clots causes the undesirable phenomenon of alveolar osteitis (AO) or dry socket. In this review, we aimed to investigate whether enhanced angiogenesis contributes to a more effective prevention of AO. The potential pro- or anti-angiogenic activity of different materials used for the treatment of AO were evaluated. An electronic search was performed in the PubMed, MEDLINE, and EMBASE databases via OVID from January 2000 to September 2016 using the keywords mentioned in the PubMed and MeSH (Medical Subject Headings) terms regarding the role of angiogenesis in the prevention of AO. Our initial search identified 408 articles using the keywords indicated above, with 38 of them meeting the inclusion criteria set for this review. Due to the undeniable role of angiogenesis in the socket healing process, it is beneficial if strategies for preventing AO are directed toward more proangiogenic materials and modalities.

Effect of fluoride gel on microhardness of flowable composites: An in vitro study

Objective: Adequate knowledge about restorative materials particularly flowable composite resins with favorable physical properties like optimal microhardness and resistance to environmental factors is a big concern for many dentists. Flowable composites have several applications for fissure sealant therapy and preventive resin restorations [PRR]; which are common treatments in pediatric dentistry. Acidulated Phosphor Fluoride [APF] topical gels can cause surface degradation and weight loss in composite resins and decrease their wear resistance. This study aimed to assess the effect of APF gel on the microhardness of flowable composites

Methods: This experimental in vitro study was conducted on 60 specimens measuring 2mm in thickness and 6mm in diameter fabricated of Tetric N-Flow [Ivoclar-Vivadent], PermaFlo [Ultradent] and Denfil [Vericom] flowable composites [n=20 for each group]. Specimens were stored in artificial saliva at room temperature for one week. The 20 specimens in each group were randomly divided into 2 subgroups of test and control [n=10]. Microhardness was measured using Vickers microhardness tester. In the control groups, 3 indentations were made on each disc on the periphery of a circle with at least 1mm distance from one another and from the specimen margin. The mean microhardness value was then calculated. The mean of all measurements was calculated as well. Test specimens were subjected to [Sultan] 1.23% APF gel for 4min and then rinsed and airdried. Their microhardness was measured again as described above. Two-way ANOVA was used to compare the effect of APF gel and type of composite on the microhardness of different flowable composites

Results: Based on the results, the microhardness of Denfil, PermaFlo and Tetric N-Flow was 16.5 [1.32], 37.36 [2.13] and 20.39 [0.52] before and 16.46 [2.20], 35.04 [2.43] and 19.13 [2.20] after the application of APF gel, respectively. The difference between the before and after values for each composite was significant [p=0.193] while the difference between different composites was statistically significant in this regard [p<0.001]

Conclusion: Exposure of Denfil, PermaFlo and Tetric N-Flow flowable composites to APF gel for 4min had no effect on their microhardness

Effect of synthetic tissue fluid on microleakage of grey and white mineral trioxide aggregate as root-end filling materials

The success of endodontic surgery has been shown to depend partly on the apical seal. Grey mineral trioxide aggregate [GMTA] produces hydroxyapatite twice as often as white mineral trioxide aggregate [WMTA] when suspended in a phosphate buffered saline [PBS] solution. The aim of this in vitro study was to compare the microleakage phenomenon of gray and white mineral trioxide aggregates as root-end filling materials after immersion in synthetic tissue fluid [STF]. 55 single-rooted extracted maxillary anterior human teeth were divided into two experimental groups of 20 teeth each, plus 3 groups of 5 teeth each as two negative and one positive control groups. The root canals were cleaned, shaped, and laterally compacted with gutta-percha. The root ends were resected and 3 mm deep cavities were prepared. The root-end preparations were filled with GMTA or WMTA in the experimental groups. Leakage was determined using a dye penetration method. Data were analysed using analysis of variance [ANOVA] at the 0.05 level of significance. Results: The mean dye leakage was 0.40 +/- 0.1 mm for GMTA and 0.50 +/- 0.1 mm for WMTA groups, respectively. There was no significant difference between the two experimental groups [P = 0.14]. Despite the different properties and behaviours of GMTA and WMTA in STF, there were no significant differences in microleakage when using GMTA or WMTA

Effect of gravity and capillarity on human saliva penetration in coronally unsealed obturated root canals

The purpose of this study was to evaluate the effect of gravity and capillarity on penetration of human salivary bacteria into the entire length of obturated root canals, and to demonstrate the dye penetration configuration. Fifty single-rooted premolars were decoronated, prepared to a standardized length of 15 mm, instrumented, and randomly divided into two groups [A and B] of 25 teeth each. Each group consisted of experimental [15 samples] and negative and positive controls [five samples each]. The experimental groups were obturated with gutta-percha and root canal sealer. The positive control groups were obturated with a single cone of gutta-percha and root canal sealer. The outer surfaces [except for the apical 2 mm] were covered with two layers of nail varnish. An apparatus containing Brain Heart Infusion broth was designed, in which the teeth were placed. The samples in Group A were placed upside down, while Group B was placed normally. The coronal portions of the samples were placed in contact with fresh saliva. The number of days required for bacteria to penetrate the entire length of canals was determined. The samples were then immersed in India ink to determine the dye penetration configuration. Data were analyzed using Student's Mest. The extent of dye penetration was significantly greater in Group B compared to Group A, and they were in a pattern rather than linear form. Gravity and capillarity insignificantly affected bacterial leakage. Although gravity and capillarity did not affect bacterial penetration when applied to the coronal access of endodon-tically treated teeth, it seems that they can promote penetration of India ink into the canal after the bacterial test on the same tooth

Efficacy of two rotary systems in removing gutta-percha and sealer from the root canal walls

The aim of this in vitro study was to compare the efficacy of two retreatment rotary systems in removal of gutta-percha [GP] and sealer from the root canal walls with and without use of solvent. Sixty single-canalled distal roots of mandibular molars were prepared and root filled with gutta-percha and AH26. Each canal was randomly allocated to receive one of the retreatment techniques, Mtwo R or ProTaper. The groups were further divided into two subgroups: with or without the use of solvent. The cleanliness of canal walls was determined by stereomicroscope and scanning electron microscopy. The results showed that Mtwo R without the use of solvent was more efficient in material removal compared to ProTaper D [P<0.05]. Most remnants were found in the apical third of the canals [P<0.05]. Mtwo R seems to be an efficient rotary system for endodontic retreatment of root canal with GP

Cyclic fatigue resistance and fractographic analysis of RaCe and ProTaper rotary NiTi instruments

This study investigated the fatigue and fracture modes of RaCe and ProTaper rotary instruments. Fatigue resistance was evaluated by rotating the files 30° or 60° and with 2 or 5mm radius of curvature. RaCe taper 06 size 25 and ProTaper Fl files [n=40] were used. The number of rotations to failure was analyzed by two-way ANOVA and independent sample t-test. Fracture surfaces were examined under a scanning electron microscope. Both files exhibited significantly more resistance to fracture when angle severity was reduced and increase in curvature radius [P=0.000]. ProTaper demonstrated higher number of cycle of failure [P=0.0029] in one group [r=5mm, 60°]. SEM observation revealed fatigue mark/features in 17 specimens, shear characteristics in 37 samples, and tensile overload in 26 samples. Radius of curvature was the main factor in torsional and fatigue failures

comparative study of MTA solubility in various media

Solubility of root filling materials is heavily influenced by the environment they are in contact with. This study compared the solubility of ProRoot MTA in deionized water and synthetic tissue fluid. Forty specimens of prepared MTA were immersed in deionized water and synthetic tissue fluid [20 samples each]. The solubility was assessed after 7 and 28 days. Scanning electron microscope observation was also performed. The mean weight loss was evaluated using a digital scale. Data were analyzed using one-way ANOVA. Tukey test was performed for multiple comparisons. MTA solubility in synthetic tissue fluid was significantly lower than deionized water after 7 and 28 days [P<0.05]. Secondary electron detectors revealed the presence of lumps and platelets on the surfaces of both specimens. Also, more voids were observed in specimen stored in deionized water. MTA dissolved faster in deionized water than synthetic tissue fluid. Despite this, the solubility of this material in both media was acceptable

impact of pH on cytotoxic effects of three root canal irrigants

Cytotoxicity of root canal irrigants is important due to their close contact with host tissues. This study was to assess the possible impact of pH on cytotoxic effects of MTAD, 17% EDTA, and 2.6% NaOCl on the human gingival fibroblasts using MTT assay. Human gingival fibroblasts were exposed to the irrigants and their viability was assessed after 1, 6, and 12 h. The pH of the medium was measured in each interval. Light absorption values were measured for each culture medium using Elisa Reader device. NaOCl had significantly less cytotoxicity than EDTA and MTAD. Also irrigants cytotoxicity decreased in 12, 1, and 6 h, respectively. It seems that variation of the pH resulted in variation in the cytotoxicity of solutions; i.e., it follows the pattern of the pH variation

Efficacy of three different methods in the retreatment of root canals filled with Resilon/Epiphany SE

The purpose of this study was to evaluate the efficacy of three methods in removal of Resilon/new Epiphany self-etch [SE] soft resin endodontic obturation system. Thirty extracted single rooted human teeth were prepared for endodontic treatment and obturated with Resilon/Epiphany SE. The roots were randomly divided into three groups; group 1 roots were retreated using Mtwo R/Mtwo files; group 2 were retreated using Mtwo R/Mtwo accompanied with chloroform; and group 3 were retreated using Mtwo R/Mtwo accompanied with Endosolv R. The cleanliness of canal walls was determined using scanning electron microscopy. Data were analyzed using ANOVA and LSD tests. Endosolv R combined with rotary files was more efficient in material removal compared to chloroform combined with rotary files and rotary files alone [P<0.05]. Also, chloroform combined with rotary file was more efficient than rotary file alone in removing filling material from the root canals. Significant difference was found within group 1 between the coronal third compared to the middle and apical thirds [P<0.05]. In group 2, there were more material remnants in the apical third [P<0.05]. In group 3, there was no significant difference between the three segments of the root canals [P>0.05]. All techniques left filling material remnants and debris on the root canal walls. Endosolv R combined with rotary files most effectively removed filling materials from the root canals, especially in the apical third

comparative study between Resilon and gutta-percha as a secondary root canal filling materials: An in vitro study

Adequate root canal seal following retreatment is essential for a successful outcome. Resilon/Epiphany [R/E] obturation system has been introduced as a substitute for conventional gutta-percha/sealer method. This in vitro study compared the amount of apical microleakage of R/E with gutta-percha/AH26 [GP/AH26] sealer as secondary root canal filling following retreatment in human teeth. Fifty human single-rooted lower premolar teeth were selected. After preparing them with ProTaper rotary NiTi instruments, all the canals were obturated using GP/AH26 sealer. After 10 days, all the samples were retreated using the same rotary NiTi instruments. The samples were divided randomly into two experimental groups A and B [n=20] and positive and negative control groups [n=5]. In group A, all canals were obturated using GP/AH26 sealer and in group B all canals were obturated using R/E. After one week incubation in 37°C with 100% humidity, the amount of apical microleakage was evaluated with fluid filtration model. All the apical microleakage data were analyzed with Mann-Whitney U test Results: The mean amounts of apical microleakage were 0.317 +/- 0.287 and 0.307 +/- 0.281 microL/8min [fluid pressure=30 cm H[2]O] in experimental group A and B respectively; the difference was not statistically significant [P>0.05]. R/E seems to be a good alternative for retreatment as a secondary root canal filling material. However, Resilon/Epiphany obturation system does not completely avert microleakage