[The therapeutic role and effectiveness of selective neck dissection in the management of N0 neck]

OBJECTIVES

To assess the therapeutic role and the effectiveness of the selective neck dissection in the management of the clinically node negative neck in the head and neck squamous cell carcinomas.

PATIENTS AND METHODS

The charts of 177 patients with squamous cell carcinoma, who underwent neck dissection between January 2000 and January 2007, were reviewed retrospectively. Seventy neck dissections in 58 patients (51 males, 7 females; mean age 63 years; range 21 to 85 years) in whom the primary site of the lesion was the larynx, oral cavity, oropharynx and hypopharynx, and who were considered to have N0 neck and to comply with the study criteria were included in the study. Details were collected on tumor site and stage, type of surgery, pathologic N stage, number and size of pathologic nodes, extracapsular spread of nodes, postoperative radiotherapy, local recurrence, follow up time and survival status in all patients.

RESULTS

It was found out that selective neck dissection operations were performed on 99 of 102 N0 patients. The follow up time was approximately 23 months in 58 patients who were found to comply with the inclusion criteria. The most frequent site for primary tumor was larynx and most patients were at T2 stage. Nine patients had pathologically positive lymph node with occult metastasis rate of 13%. The overall recurrence rate was 19%. Postoperative radiotherapy was used as adjuvant therapy in 15 patients. Regional control rate was lower in patients with pathologically positive lymph nodes. However, it was not statistically significant.

CONCLUSION

Selective neck dissection is an effective and safe method for controlling and staging of the patients with clinically N0 neck.

Evaluation of the effect of dexamethasone in experimentally induced endolymphatic hydrops in guinea pigs

PURPOSE

The aim of this study was to investigate the audiological and histopathologic effects of dexamethasone in the treatment of experimentally induced endolymphatic hydrops.

MATERIALS AND METHODS

Thirty mature, male guinea pigs weighing 400 +/- 50 g were operated on to induce experimental endolymphatic hydrops in their right ear. Left ear served as control. Subjects were separated into control and dexamethasone groups, with the latter receiving dexamethasone 5 mg/(kg d) intraperitoneally for 10 days. Electrocochleography and auditory brainstem response were applied to all subjects at preoperation, on the second postoperative day and also on the 15th postoperative day in animals that lived for a long time. The histopathologic examination of the inner ear in all animals was done at the end of the study.

RESULTS

The summating potential and the ratio of the summating potential to the action potential measured on the second postoperative day were found to be increased in both groups, but more significantly in the control one. When the left and right ears were compared, significant difference was found in the control group; however, no significant difference was found between the ears in the dexamethasone group. Histopathologic examination revealed varying degrees of hydrops in the control group, but showed only normal findings or minor changes in the dexamethasone group.

CONCLUSIONS

Dexamethasone can prevent the audiological and histopathologic findings of experimentally induced endolymphatic hydrops. However, these results must be supported by clinical and experimental studies designed with a large number of subjects.

Surgical approaches for antrochoanal polyp: a comparative analysis

OBJECTIVE

The aim of this study was to evaluate the clinical and histopathological characteristics of antrochoanal polyps (ACPs) and to perform a comparative analysis of surgical techniques in terms of recurrence.

METHODS

The clinical, radiological and histopathological features of 42 patients with a diagnosis of ACP who underwent surgery in a period of 6 years (January 2000 - January 2006) were investigated retrospectively. Histopathological examinations were present for all patients and were re-examined for histological analysis.

RESULTS

Endoscopic sinus surgery (ESS) was performed in all patients. Transcanine sinoscopy (TS) and the Caldwell-Luc approach (CL) were used in addition to ESS in 14 and 13 patients respectively. The attachment site was detected in 21 patients (50%) and the most frequent site was found to be the lateral wall in 15 patients (71.4%). There was no relationship between the choice of surgery, the attachment site or accessory ostium, or any sinusitis with ACP. Histological examination showed prominent eosinophilia in 29 patients (69%). The follow-up time was a minimum of 12 months with a mean of 28.9 months. Three recurrences were seen after ESS. However, there was no recurrence after ESS+TS and ESS+CL.

CONCLUSION

Our study showed that the most important factors affecting the choice of surgical approaches are the preference of the surgeon, the age of the patient and the presence of recurrent disease. Combined approaches with either TS or CL should be considered, particularly when the attachment site of the antral part of ACP is undetected, in order to prevent incomplete excision and recurrences.

Bactericidal efficacy of Er,Cr:YSGG laser irradiation against Enterococcus faecalis compared with NaOCl irrigation: an ex vivo pilot study

AIM

To compare the efficacy of a standard NaOCl irrigation procedure with that of Er,Cr:YSGG laser irradiation in contaminated root canals having small and large apical foramina.

METHODOLOGY

Forty root canals of extracted central incisor teeth with straight roots were chosen so that their apical foramina just permitted the tip of a size 20-K file to pass through. The canals were then enlarged with files to size 60 and randomly divided into four groups of 10 teeth each. The apical foramina of one group were widened further so that the tip of a size 45-K file could just pass through. After sterilization, all roots were inoculated with Enterococcus faecalis for 48 h at 37 degrees C. The first group was used as a control, the second group was irrigated with 3% NaOCl solution for 15 min, and the last two groups having different sizes of apical foramina were irradiated with the Er,Cr:YSGG laser at output power from 0.5 W, with 20% air and water levels. The disinfecting efficacy of the groups was tested by collecting dentine chips from the inner canal walls of the specimens and counting viable E. faecalis on Mueller-Hinton agar plates.

RESULTS

The differences in the mean number of viable colonies between the control and laser groups were statistically significant (P < 0.05). The control specimens had the highest number of microorganisms (153 x 10(3) +/- 39 x 10(3)). Complete sterilization was achieved in the 3% NaOCl group. The mean colony forming units (CFU) values obtained after Er,Cr:YSGG laser irradiation were 6.6 x 10(3) CFU and 6.5 x 10(3) CFU in root canals having large and small apical foramina respectively.

CONCLUSION

In teeth with straight roots the Er,Cr:YSGG laser reduced the viable microbial population in root canals with small and large apical foramina but did not eradicate all bacteria. Three percent NaOCl inhibited the growth of E. faecalis and effectively sterilized all root canals.

Hyperaeration of the frontal sinus

The nasal cavity and paranasal sinuses constitute an anatomical and functional unit. Paranasal sinuses communicate with the nasal cavities, which are covered by the same mucosa, via small openings and narrow ducts that allow both aeration and sinus drainage. Anatomical variations of the paranasal sinuses and nasal cavity are important in sinus diseases. Computerized tomography (CT) plays a critical role in evaluation of the patients with paranasal sinus pathology and variations. A 38-year-old man admitted to our clinic with headache and postnasal dripping for 1 year. His paranasal CT scanning revealed that there is hyperaeration of the frontal sinus which is in continuity with the sphenoid sinus. Hyperaeration of the sinuses may be kept in mind in a patient complaining of headache.

Thyroid cancer in hyperthyroidism: incidence rates and value of ultrasound-guided fine-needle aspiration biopsy in this patient group

Three hundred and thirty-three hyperthyroidism cases were retrospectively investigated to provide information about the association between hyperthyroidism and thyroid cancer. There were 112 cases of toxic multinodular goiter (TMNG), 77 cases of toxic nodular goiter (TNG) and 144 cases of Graves' disease (GD). All nodules detected in GD patients, all nodules greater than 1 cm diameter in nodular goiter patients, nodules 5-10 mm size diameter if they had calcification were fine-needle biopsied (FNAB) under ultrasound guidance (US-guided), and a total of 612 such biopsies were performed. The biopsy samples were cytologically assessed as benign (no.=552; 90.2%), suspicious (no.=6; 1.1%), malignant (no.=13; 2.1%), or inadequate for diagnosis (no.=41; 6.7%). All patients with a biopsy diagnosis of malignant or suspicious nodules underwent surgery. Histological examination confirmed the diagnosis of thyroid cancer in all 13 (2.1%) patients with malignant FNAB findings. Papillary thyroid carcinoma (PTC) was identified in 2 patients with TMNG (%1.8), 5 with TNG (%6.5) and 5 with GD (%3.5). Metastatic follicular thyroid carcinoma (FTC) was identified in a patient with TNG. Thyroid malignancy (micro- or macrocarcinoma) was diagnosed pre-operatively in all 13 cases by US-guided FNAB. Thyroid cancer was diagnosed in 6 (5.5%) of the 109 nodules detected in the TNG group, 2 (0.44%) of the 452 nodules detected in the TMNG group, and 5 (9.8%) of the 51 nodules detected in the GD group. Two (2.6%) of the 77 functioning nodules in the TNG patients were malignant, but none of the 402 functioning nodules in the TMNG patients was malignant. In patients with hyperthyroidism, US-guided FNAB is useful for detecting thyroid cancer in nodules greater than 5 mm diameter before radioiodine therapy or surgery.

Antibacterial activities of MDPB and fluoride in dentin bonding agents

The aim of this study was to compare in vitro antibacterial activity of MDPB containing bonding system ABF with activities of three Fluoride containing bonding systems (Fuji Bond LC (FBLC), Prime&Bond NT (PBNT), and FluoroBond (FLB). Two bacterial strains were tested: Streptococcus mutans and Lactobacillus acidophilus. The study was performed on Muller Hinton Agar by Agar Well Technique. The bacterial agar was evenly distributed over the surface of petri dishes. Standard wells were punched into the agar. The test materials were placed in the wells of Muller Hinton agar plates, inoculated with Streptococcus mutans NCTC10449 and Lactobacillus acidophilus. The diameters of inhibition zones produced around the materials were measured after 24 h of incubation at 37 +/- 1 degrees C. For statistical analysis, Duncan's multiple range test was used. The primers of bonding agents were highly effective against to Streptococcus mutans. The MDPB containing primer of ABF Bond produced the greatest inhibition zones against to Lactobacillus acidophilus. It was followed by FLB primer. Lactobacillus acidophilus was resistant to FBLC primer and bonding, ABF, PBNT and FLB bonding agents. The results of this study indicated that, incorporation of MDPB in primer of self-etch system increased its antibacterial activity especially against to Lactobacillus acidophilus. However, all bonding systems except for bonding agent of ABF showed some antibacterial activity against to Streptococcus mutans.

Evaluation of internal adaptation in ceramic and composite resin inlays by silicon replica technique

This study was aimed at investigating the internal adaptation of a ceramic (Ceramco II) and two composite resin inlay materials (SureFil and 3M Filtek Z 250) using silicon replica technique as an indicator. Forty-five standard mesial-occlusal-distal (MOD) cavities were prepared into brass moulds by using computer numerically controlled system. Inlays were prepared according to manufacturers' instructions with indirect methods. Replicas of the prepared cavities and inlays were produced with a polyvinyl siloxane material (Elite H-D). The spaces between inlays and cavities were filled by different coloured light-body polyvinyl siloxane material. Two parallel slices (mesio-distally) were obtained from the replicas with a sharp blade. Different coloured polyvinyl siloxane material thickness between cavity and inlay was measured at seven points (mesial, occlusal and distal). The data were evaluated with anova and Tukey's honestly significantly different (HSD) statistical tests. In the SureFil and Ceramco II groups, the sizes of the contraction gaps at mesial and distal gingival floors were greater than that of the occlusal marginal walls. In comparison of gap formation at occlusal regions, while the 3M composite group showed highest gap values (204.33 +/- 75.45 microm), the Ceramco II group revealed the lowest (141.17 +/- 23.66 microm) (P < 0.05). At the gingival floors, gap formation of Ceramco II group was the highest (227.08 +/- 51.95 microm). Neither the 3M Filtek Z250 nor SureFil group showed any statistical difference between gap values of their self-occlusal and gingival floors (P > 0.05). In conclusion, our results showed that ceramic inlays did not confer any big advantage for internal adaptation over the composite inlays.

Epithelial cyst of the soft palate

Epithelial cysts are benign epithelium-lined lesions that contain fluid or semisolid material. This type of cyst is rare in the oral cavity. Most epithelial cysts in this location are situated in the anterior floor of the mouth; the soft palate is seldom affected. Oral examination in a 6-year-old boy revealed a cyst in the soft palate. The lesion was excised under general anesthesia, and histopathological examination identified it as an epithelial cyst. The report discusses this rare location for an epithelial cyst and reviews the pertinent literature.

Tracheopathia osteoplastica associated with iron deficiency anemia

Tracheopathia osteoplastica (TPO) is a benign disease of trachea characterised by numerous cartilaginous or bony structures protruding into tracheobronchial lumen. We report a case of a 85-year-old male patient in whom tracheopathia osteoplastica was diagnosed incidentally during bronchoscopy which was missed on chest computed tomography examination. The patient also had iron deficiency anemia, the cause of which was not identified. We review TPO and discuss the associated abnormalities reported in the literature.

Anin vitrocomparison of adhesive systems to seal pulp chamber walls

AIM

To compare in vitro the sealing properties of five different dentine adhesive materials (Prime&Bond NT (PBNT); Prompt L-Pop (PLP); Clearfil SE Bond (CSEB); Scotchbond Multi Purpose Plus (SMPP); EBS-Multi (EBSM)) inside the pulp chamber.

METHODOLOGY

Seventy-five recently extracted human molar teeth were used. The roof of the pulp chambers and roots were removed under water cooling. Pulp tissue was removed, and the canal orifices were sealed. The pulp chambers were then treated with 5% sodium hypochlorite (NaOCl) for 1 min. The teeth were randomly divided into five groups of 15 teeth each. Adhesive systems were applied to the pulp chamber walls according to the manufacturers' instructions. The samples were connected to Plexiglass plates, and a fluid filtration method was used for quantitative evaluation of leakage. Measurements of fluid movement were made at 2-min intervals for 8 min. The quality of seal of each specimen was measured immediately, after 24 h, 1 week and 1 month. The data were statistically analysed by repeated-measurements multivariate anova, Friedman test, Wilcoxon signed rank test, Kruskal-Wallis of one-way anova and Mann-Whitney U-tests. The pulp chamber wall with and without NaOCl and resin-dentine interfaces of specimens were observed under a scanning electron microscope (SEM).

RESULTS

The leakage values of the materials were significantly different at different measurement periods. In all groups, leakage values decreased with time (P < 0.05). PBNT and PLP had the least leakage during immediate measurements (P < 0.05). After 1 month, leakage of all adhesive systems was not significantly different (P < 0.05). SEM observation of pulp chamber walls demonstrated that the irregular dentine surface without smear layer was present in the nontreated group. However, NaOCl application removed the collagen fibrils leaving the dentine surface smooth. At resin-dentine interfaces of specimens, no hybridization zone was observed.

CONCLUSIONS

None of the materials had created a perfect seal to the pulp chamber walls. PBNT and PLP had better sealing over the short term, but over the long term, there were no differences between the materials.

Effect of home bleaching agents on the microhardness of human enamel and dentin

In this study, the effects of home bleaching agents that contains carbamide peroxide (in different concentrations such as 10 and 15%) on the surface hardness of human enamel and dentine were evaluated. The buccal surfaces of 90 recently extracted human mandibular anterior teeth were used. The specimens in the dentine group were ground to expose of dentine surface. Then, samples in both enamel and dentine group were randomly divided into six main groups with 15 in each group. In the group 1 and 4, 15% carbamide peroxide was applied to the enamel and dentine surfaces and then the teeth were left in an incubator at 37 degrees C and 100% humidity for 4 h first, then left 28 h after repeating the same procedures seven times. The teeth were treated with 10% carbamide peroxide in groups 2 and 5 and distilled water in groups 3 and 6 (control groups), using the same procedures. Vicker's microhardness of enamel and dentine were assessed on each tooth before and after each treatment period (4 and 28 h). The hardness of control group specimens was also obtained after 4 h in distilled water and then after 28 h. For statistical analysis one-way ANOVA and post-hoc Tukey tests were used. For both 10 and 15%, there were no statistically significant differences between the untreated control specimens and the specimens treated with the bleaching materials for enamel and dentine at any given measurement time (P > 0.05). Nevertheless, in vivo use of bleaching agents on tooth hard tissues requires further analysis.

Influence of dentinal regions on bond strengths of different adhesive systems

This in vitro study assessed comparatively the shear bond strengths of three composite resins, 3M Valux Plus (3MVP), Herculite (H), Clearfil AP-X (CAP-X), a polyacid modified composite resin Dyract (D), and a resin modified glass-ionomer materials Vitremer (V), to cervical and buccal dentine regions of extracted human molar teeth. Four different bonding systems, 3M ScotchBond Multipurpose (SB), Clearfil Liner Bond 2 (LB2), Opti Bond (OB), and Prime & Bond 2.1 (PB 2.1) were used with the manufacturer's respective composite and compomer materials. One hundred freshly extracted mandibular molar teeth were selected for this study. Flat buccal dentine surfaces were created on 50 teeth and cylindrical rods of the five materials were bonded to the dentine surfaces. For assessment of cervical bond strengths, the materials were bonded to mesial and distal enamel bordered occlusal dentinal surfaces of the remaining 50 teeth. The five groups of restorative procedures were applied as follows; Group 1: SB + 3MVP, Group 2: LB2 + CAP-X, Group 3: OB + H, Group 4: PB2.1 + D, Group 5: Vitremer primer (VP) VP + V. Each restorative procedure thus had 20 specimens (10 buccal + 10 cervical). After 24 h of water storage (37 degrees C), the specimens were tested on a Universal Testing machine in shear with a cross head speed of 0.5 mm min-1. The bond strength values were calculated in MPa and the results were evaluated statistically using Kruskal-Wallis one-way/anova and Mann-Whitney U-tests. It was found that the bond strengths of SB + 3MVP, LB2 + CAP-X and VP + V to buccal dentine surfaces were significantly stronger (P < 0.05) than those to the occluso-cervical dentine floors. When the bond strengths to the occluso-cervical dentine and buccal dentine surface were compared, there was no significant difference between the materials (P > 0.05). Vitremer was found the least successful adhesive material in terms of shear bond strength on both buccal and occluso-cervical dentine surfaces.

The effect of simulated intrapulpal pressure on bond strength to enamel and dentine

The purpose of this study was to evaluate the effect of simulated intrapulpal pressure on the shear bond strength (SBS) of a self-etching bonding system (Clearfil Liner Bond II) to both enamel and dentine surfaces. Forty-two caries-free human molar teeth were randomly assigned to two equal groups (n=21). One group of 21 teeth was connected to a special pulpal pressure machine, which is developed to simulate in vivo conditions. The buccal and lingual surfaces of the teeth were prepared with a diamond wheel to create flat dentine and enamel surfaces. A self-etching bonding system was then applied under pulpal pressure and 2.5 mm diameter composite cylinders were bonded to the prepared surfaces. The samples were then stored in distilled water at room temperature for 24 h under pulpal pressure before SBS was tested. The second restored group was used as a control and the teeth were not connected to the pulpal pressure apparatus during material application and test procedures. They were stored for 24 h in distilled water at room temperature before the SBS test. Fracture analysis of the enamel and dentinal surfaces was performed using a stereomicroscope. Shear bond strength values to dentine was significantly reduced with pulpal pressure (P < 0.001). However, in the enamel, SBS was increased (P < 0.001). In the control group, the SBS values to dentine and enamel did not show any significant difference (P > 0.05). Based on these results, it can be concluded that further analysis of enamel histology and bonding mechanisms are needed.

Comparison of antibacterial activity of two dentin bonding systems using agar well technique and tooth cavity model

OBJECTIVE

This study compared the antibacterial activities of two dentin bonding systems (ABF, Kuraray and Reactmer Bond, Shofu) by a conventional agar well technique and a newly designed in vitro test using tooth model.

METHODS

In the agar well technique, the test materials were filled in the wells of Muller Hinton agar plates inoculated with Streptococcus mutans NCTC10449, and the diameters of inhibition zones produced around the materials were measured after 24h of incubation. For the tooth model test, three cavities (diameter 1mm, depth 2mm) were prepared in the flat occlusal dentin of human extracted molar. After sterilization, the teeth were left in broth culture of 1.56 x 10(8)CFU/ml of S. mutans at 37 degrees C for 72h for allowing bacteria to invade the cavity. The dentin bonding systems were applied separately to each of the two infected cavities, and the third cavity was left unapplied for control. After sealing the occlusal surfaces, the teeth were kept in physiologic saline solution at 37 degrees C for 72h. The standardized amounts of dentin chips (120+/-5mg) were obtained from the cavity walls and the number of bacteria recovered was determined. The results were analyzed by One Way ANOVA, Kruskal Wallis and Mann-Whitney's U tests.

RESULTS

The primer of ABF and Reactmer Bond produced inhibition zones with similar sizes (p>0.05), but the bonding resin of ABF did not produce any inhibition. When tested by the model cavity method, the application of ABF resulted in significantly less bacterial recovery than Reactmer Bond (p<0.05), demonstrating substantial antibacterial effects.

CONCLUSIONS

The tooth model method used in this study was effective for evaluating the substantial antibacterial effects of dentin bonding agents, and the experimental dentin bonding system ABF was demonstrated to be able to inactivate the bacteria in the cavity effectively in comparison with little antibacterial activity shown by Reactmer Bond.

Shear bond strengths of tooth fragments reattached or restored

This study investigated the shear bond strengths of sectioned human mandibular incisor edge fragments reattached using luting cements, bonding agents or restored with composite resins. Seventy teeth were randomly distributed among six experimental groups and a control group. Leaving half of the anatomic crowns exposed, the teeth were embedded in self-cure acrylic resins with the exposed part then sectioned. The fragments in groups 1-4 were bonded to their respective teeth using Clearfil Liner Bond 2V, Scotch Bond Multi Purpose Plus, Panavia-F and 3M Opal Luting cement. The 5th and 6th groups were restored with composite resins (Silux 3M and Clearfil AP-X) using their bonding agents (Single Bond and Clearfil SE Bond). The results indicated that reattachment of fractured incisal fragments by using new generation bonding agents was effective against shear stresses, comparable with the intact teeth. Instead of restoration with composite resins therefore reattachment of a fractured fragment might be more preferable in cases of dental trauma.

Bond strength of five current adhesives to caries-affected dentin

Five current dentin adhesives were evaluated for their ability to bond to caries-affected dentin. The materials were: total etch [Solid Bond (SB)], two self-etch [Clearfil SE Bond (CSE), Etch and Prime (EP)], two one bottle [Prime and Bond 2.1 (PB), One Coat Bond (OCB)]. Sixty extracted molar teeth with proximal caries (mesial or distal) extending into mid-dentin were used. By grinding normal and caries-affected proximal surfaces, flat dentin surfaces were obtained. The surfaces were then bonded with each adhesive system and composite resins were added to the surfaces by packing the material into a cylindrical-shaped plastic matrix with an internal diameter of 2.5 mm and height of 3 mm. Shear bond testing was performed following 10 days incubation of specimens in distilled water at 37 degrees C. Results were analysed by Kruskal-Wallis ANOVA, and Mann-Whitney U multiple comparison test and Wilcoxon rank tests. The results obtained with CSE, SB, and EP were similar in caries affected and normal dentin (P > 0.05). But bonds made to normal dentin with OCB and PB were lower (P < 0.05) than bonds to caries-affected dentin. Bonding to caries-affected dentin with CSE (24.49 +/- 5.38), SB (21.49 +/- 9.15), and EP (21.19 +/- 9.17) showed shear bond strengths higher than OCB (17.43 +/- 9.78) and PB (14.10 +/- 7.94) (P < 0.05). Bonding to normal dentin with CSE (29.91 +/- 8.95) was the highest (P < 0.05). SB (21.17 +/- 5.41) and EP (17.45 +/- 6.21) showed shear bond strengths higher than OCB (11.99 +/- 10.15) and PB (10.57 +/- 4.56) (P < 0.05).

Amalgam repair: evaluation of bond strength and microleakage

This study evaluated the tensile bond strength of "repaired" amalgams and compared the degree of microleakage. Amalgam (Cavex avalloy) was condensed into plastic tubes (3 mm in diameter, 10 mm in height) to the half-length. After storage in water at 37 degrees C for two days, the remaining parts of tubes were filled with amalgam (A), cavity varnish (CV)+A, Liner Bond 2V (LB2V)+A, 3M Opal Luting Cement (3MOLC)+A, Panavia F(PF)+A, Metabond(MB)+A, Fuji BondLC(FB)+A, HytacOSB(HOSB)+Hytac Aplitip (H), Liner Bond2V+Clearfil AP-X(CAP). The bond strengths for 15 samples of each restoration group were determined. For the microleakage study, MOD cavities of 90 extracted human premolars were used. The distal half of cavities were filled with amalgam. After storage in water at 37 degrees C for two days, the mesial half of the cavities were filled to simulate a clinical repair. The "repair" was placed using the procedures applied in the bond strength study. The teeth were stained with basic fuchsine (0.5%), sectioned and evaluated for dye penetration. In both parts of study, the data were analyzed by ANOVA and Duncan's multiple range tests. Bond strength values (MPa) were: A+PF+A 3.84+/-1.08, A+LB2V+A 3.15+/-0.97, A+LB2V+CAP 3.05+/-0.53, A+MB+A 2.86+/-0.88, A+HOSB+H 2.58+/-0.51, A+3MOLC+A 2.11+/-0.75, A+FB+A 0.68+/-0.59. The repaired A+A and A+CV+A groups were separated before testing. The A+PF+A group showed the highest bond strength (p<0.05). Microleakage in the cervical margins of repaired restorations was lower in the amalgam groups than microleakage in the resin composite and compomer groups. PF, MB, 3MOLC and FB performed better at the amalgam "repair" interface. The A+LB2V+A group showed no microleakage at both the occlusal and gingival test regions.

Bonding strength to two different surfaces of dentin under simulated pulpal pressure

PURPOSE

The purpose of this in vitro study was to measure and compare the in vitro shear bond strengths (SBS) of the following dentin bonding systems to different dentin surfaces under simulated pulpal pressure: Liner Bond 2 (self-etching) (LB2), Liner Bond 2V (self-etching) (LB2V), Opti Bond Solo (single component) (OBS), Fuji Bond LC (filled) (FBLC), Prime & Bond 2-1 (single component) (P&B2-1), and Solid Bond (total etching) (SB).

MATERIALS AND METHODS

Occlusal and buccal surfaces of 60 extracted human molars were prepared to expose the dentin bonding surface. After being wet ground with 600-grit abrasive papers, teeth were randomly assigned to 6 equal groups of 10 each. The dentin surfaces were treated with the bonding systems mentioned above, and resin composite cylinders (Clearfil AP-X) were built up under simulated pulpal pressure when diluted bovine serum was used as the pulpal fluid. After one day of storage in 37 degrees C water, the specimens were shear tested to failure on an Instron machine.

RESULTS

The data were statistically analyzed with the Student's t-test and a post hoc Tukey test. Comparing buccal surfaces, the post hoc Tukey test indicated no significant differences among all the test groups (p > 0.05). On occlusal surfaces, the post hoc Tukey test indicated significant differences among the tested groups (p < 0.05). The Student's t test revealed significant differences between the occlusal and buccal shear bond strength values in LB 2, LB2V, and SB groups (p < 0.05).

CONCLUSION

The strength of adhesion to dentin depends upon both the adhesive system used - with self-etching systems tending to show higher bond strengths than the other materials tested - and the location of the dentin, with significantly higher SBS being found on buccal surfaces in 3 of the 7 tested bonding systems.

Regional bond strengths of adhesive resins to pulp chamber dentin

Microleakage of oral microorganisms, which can occur due to the lack of sealing ability of permanent restorative materials, may cause failure of root canal treatments. Although a great deal of research has been done on sealing enamel and coronal dentin with resins, little research has been done on the adhesion of resins to the walls of pulp chambers. The purpose of this study was to evaluate regional bond strengths of two adhesive systems to the walls of pulp chambers. A section was made horizontally through the middle of the pulp chamber of extracted human third molars to divide the chamber into upper and lower halves. The pulp tissue was removed and the tooth segments were then divided into treatment subgroups. The pulp chambers were bonded with C&B Metabond (Parkell) or One-Step (Bisco), with or without 5% NaOCI pretreatment. The microtensile bond strengths of these resins to four different pulp chamber regions (bottom, wall, roof, and pulp horn areas) were then measured using an Instron machine. The data were expressed in MPa and were analyzed by a three-way ANOVA. Statistically significant differences were found among the test groups (p < 0.001). One-Step produced higher bond strengths to all pulp chamber regions except the floor, compared with C&B Metabond. The results indicated that high bond strengths can be achieved between adhesive resins and the various regions of the pulp chamber. This should permit the use of a thick layer of unfilled resin along the floor of the pulp chamber and over the canal orifices as a secondary protective seal after finishing root canal therapy.

A simple method for single anterior tooth replacement

PURPOSE

This article reports a case in which a recently extracted tooth was used as a natural tooth pontic bonded to the teeth on either side of the missing tooth using a Ribbond ribbon.

MATERIALS AND METHODS

A bondable, reinforcing polyethylene ribbon was used to bond a natural tooth pontic to adjacent teeth.

RESULTS

Acceptable esthetics were obtained and the result was satisfactory for the patient.

CONCLUSION

After one year of clinical use, direct construction of a single-tooth replacement using the natural tooth pontic still provided satisfactory esthetics and function. The technology which makes this adhesive restoration possible is the development of a high strength, high molecular weight, biocompatible polyethylene fiber. This easily handled material must be evaluated in long-term clinical studies.

Effect of cavity varnish, amalgam liner or dentin bonding agents on the marginal leakage of amalgam restorations

The purpose of this in vitro study was to compare marginal leakage of Class II amalgam restorations lined with different agents (two new generation dentin bonding systems, a cavity varnish and an amalgam liner). Forty freshly extracted human molar teeth were divided into five groups. Class II preparations were prepared in the mesial and distal surfaces of each molar. While the cavities in two groups were lined with two new generation bonding systems, the other two groups were treated with an amalgam lining material and a cavity varnish. Fifth group was used as control, without any lining. Amalgam* was hand-condensed into each preparation. Specimens were thermocycled, stained and sectioned. Microleakage was graded using a stereomicroscope. Mean microleakage scores for occlusal and cervical margins were calculated and analysed. For the leakage values on occlusal margins, Kruskal-Wallis test indicated no significant difference in all groups. For the leakage values on cervical margins, Kruskal-Wallis test indicated significant difference in four groups when compared with controls (P < 0.001). On the other hand, there was no significant difference between the occlusal and cervical leakage values in each group.

The effect of additional enamel etching and a flowable composite to the interfacial integrity of Class II adhesive composite restorations

This in vitro study evaluated the interfacial integrity of Class II resin composite restorations. The influence of a flowable composite and additional enamel etching was also evaluated. Deep, saucer-shaped Class II cavities were prepared in the mesial and distal proximal surfaces of 25 extracted human molars and assigned to five treatment groups. The gingival margins were extended to approximately 1 mm above the CEJ in 40 cavities and below the CEJ in 10 cavities. The prepared cavities were then restored with a self-etching primer system (Clearfil Liner Bond II) and a hybrid resin composite (Clearfil AP-X), with and without a flowable composite (Protect Liner F) and additional enamel etching with 37% phosphoric acid gel (K-etchant). After finishing, polishing and thermocycling (4 and 60 degrees C, x300), the samples were longitudinally sectioned through the restorations and resin-tooth interfaces were observed directly under a laser scanning microscope. Statistical analysis indicated that the use of a flowable composite produced significantly more (p = 0.04) gap-free resin-dentin interfaces than teeth restored without the flowable composite. However, both flowable composite and enamel etching could not prevent gap formation at enamel-resin interfaces and crack formation on enamel walls.