Journal of Dental Sciences

Comparative study of apically extruded debris using one manual and two rotary instrumentation techniques for endodontic retreatment

Alper Kustarci, Demet Altunbas, Kerem Engin Akpinar — 2011-11-07

Abstract: Background/purpose: The aim of the this study was to compare the amount of debris apically extruded during endodontic retreatment using two rotary nickel–titanium (NiTi) instruments (K3 and R-Endo) and Hedström files.Materials and methods: Forty-five extracted human mandibular premolar teeth were used in this study. Root canals of the teeth were filled before being randomly assigned to three groups. In group 1, gutta-percha was removed with K3 (SybronEndo, West Collins, CA, USA) rotary NiTi instruments. In group 2, gutta-percha was removed with R-Endo (Micro-Mega, Besançon, France) rotary NiTi instruments. In group 3, gutta-percha was removed using Hedström files (Dentsply Maillefer, Ballaigues, Switzerland). Debris extruded from the apical foramen was collected into Eppendorf tubes. The liquid inside the tubes was dried, and the debris in each group was weighed and compared. Data were statistically analyzed using one-way analysis of variance, and Kruskal–Wallis test and Mann–Whitney U test.Results: Although all retreatment techniques resulted in apical extrusion, groups 1 and 2 produced significantly less apical extrusion than group 3 (P<0.05). No statistically significant difference was found between groups 1 and 2 (P>0.05).Conclusion: All retreatment techniques produced extruded debris during endodontic retreatment; however, both rotary NiTi systems were associated with less apical extrusion than manual instrumentation with Hedström files.

Effects of the type and rigidity of the retainer and the number of abutting teeth on stress distribution of telescopic-retained removable partial dentures

Volkan Sahin, Funda Akaltan, Levend Parnas — 2012-02-22

Abstract: Background/purpose: Little is known about the force-transmission characteristics and patterns of telescopic-retained removable partial dentures (RPDs) as related to their type and rigidity (rigid and/or resilient) and the number of abutting teeth supporting the telescopic dentures. In this study, we compared the strain around the abutting teeth and edentulous ridges supporting telescopic-retained RPDs with different designs using a strain gauge technique.Materials and methods: A maxillary model including four abutting teeth (# 14, 13, 23, and 24) was constructed and is referred to as Case 1. In total, four RPD frameworks (two resilient and two rigid) were fabricated for Case 1 with a conventional telescope retainer and attachment-retained telescopic retainer (ARTR) groups. A vertical static load of 280 N was applied, and strain values obtained from the strain gauges were recorded. RPDs were modified according to the following cases—Case 2 included teeth 14, 13, and 23; Case 3 included teeth 14 and 13; and Case 4 included teeth 13 and 23—and measurements were repeated. A randomized block analysis of the variance test was conducted using a general linear model procedure with statistical software. Multiple comparisons between groups were performed using Tukey’s honest significant difference test (α=0.05).Results: RPDs with an ARTR produced more strain distal to the abutting teeth than RPDs with a conventional telescope retainer. Both retainer types with a rigid design produced more strain distal to the abutting teeth than did retainers with a resilient design. RPDs supported by four, three, and two unilateral abutting teeth produced similar strain patterns. RPDs supported by two bilateral abutting teeth produced the highest strain distal to the abutting teeth, but there was no significant difference between the strains produced by RPDs supported by either two unilateral or bilateral abutting teeth. The highest strain values were obtained from strain gauges distal to the “terminal” abutting teeth. Directions of the principal strain were in a vertical direction for gauges located distal to the terminal abutting teeth. More strain was produced on the posterior edentulous ridges.Conclusion: RPDs with an ARTR and both retainer types with a rigid design produced more strain distal to the abutting teeth. Using more than two abutting teeth did not improve the strain patterns of the tested RPDs. More strain was produced on the posterior edentulous ridges.

Effects of increasing the jaw opening on the maximum bite force and electromyographic activities of jaw muscles

Duygu Koc, Arife Dogan, Bulent Bek, Meryem Yucel — 2012-02-22

Abstract: Background/purpose: Increased occlusal jaw opening may lead to some changes in the bite force and electromyographic (EMG) activities of the jaw muscles. This in situ study was conducted to determine the immediate influence of three different occlusal vertical dimensions on the maximum bite force and EMG activities of the masseter and anterior temporalis muscles.Materials and methods: Five healthy subjects participated in the study. Two maxillary occlusal splints of 2 and 4 mm thickness were fabricated, and their use created, respectively, 8 and 10 mm of intermolar distances in the first molar region with a strain-gauge-mounted metal arch. EMG activities of the muscles and the maximum bite force were simultaneously recorded using an EMG device and two miniature strain-gauge transducers. Recordings were made in the first molar region without a splint, but with two splints to produce 6, 8, and 10 mm of intermolar distances.Results: EMG activities of both muscles decreased with increased jaw opening; however, the differences were not statistically significant. The highest maximum bite force was found at a 6-mm intermolar distance, which significantly differed from those at 8- and 10-mm intermolar distances (P < 0.05). The most efficient bite force was exerted with 6 mm of intermolar distance. The least EMG activity of both muscles was found with 10 mm of intermolar distance.Conclusion: An increase in the vertical thickness of the splint to 10 mm may provide an immediate effect of reducing masseter and anterior temporalis muscle hyperactivity.

Effects of different surface treatments on the bond strength of glass fiber-reinforced composite root canal posts to composite core material

Murat Kurt, Ahmet Umut Güler, İbrahim Duran, Altay Uludamar, Özgür İnan — 2012-02-20

Abstract: Background/purpose: The purpose of this study was to investigate the effects of different surface treatments on the bond strength of glass fiber-reinforced composite (FRC) posts to composite core material.Materials and methods: A total of 18 FRC posts were randomly divided into six groups (n = 3), one of which was the untreated control group. Surface treatment of other groups were as follows: airborne particle abrasion with 50-μm Al2O3 powder at 60 psi for 10 seconds through a nozzle distance of 10 mm; etching with 4% hydrofluoric (HF) acid; and surface preparation with an Er:YAG laser under three different power settings (of 300, 400, and 500 mJ, at 2 Hz and 100 μS). A cylindrical Teflon mold was used to surround the treated posts, and the mold was filled with dual-cure composite core material. All samples were light-cured for 60 seconds through the top of the mold. After 24 hours of storage in water, specimens were sectioned perpendicular to the bonded interface under water cooling to obtain 2-mm thick post-and-core specimens. Each group consisted of 12 specimens. Push-out tests were performed at a cross-head speed of 0.5 mm/minute using a universal testing machine. Data were analyzed by one-way analysis of variance followed by Tukey’s honestly significant difference test (α = 0.05).Results: The lowest bond strength was observed in the Er:YAG 500-mJ group (6.14 ± 0.94 MPa). The acid-etched group revealed a higher bond strength (15.08 ± 0.92 MPa) than the control group. The highest bond strength was observed in the airborne-particle abrasion group [18.89 ± 0.83 MPa (P < 0.05)].Conclusion: Er:YAG laser treatments on the FRC post surface decreased the bond strength. Airborne-particle abrasion and HF acid etching are alternative methods for increasing bond strength of FRC posts to composite core material.

Degree of conversion of three fissure sealants cured by different light curing units using micro-Raman spectroscopy

Ario Santini, Vesna Miletic, Deri Koutsaki — 2012-02-22

Abstract: Background/purpose: Monomer to polymer conversion is important for optimal mechanical properties and resistance to biodegradation of resin-based materials. Incomplete conversion of fissure sealants may account for lower retention and fracture resistance as well as elution of leachable components. The objective of this study was to determine the degree of conversion (DC) of three fissure sealants cured using a conventional quartz-tungsten halogen (QTH) or a high power light-emitting diode (LED) light-curing unit using micro-Raman spectroscopy.Materials and methods: Delton Opaque and Helioseal Opaque and Helioseal Clear were applied to 60 noncarious permanent molars and cured with the QTH or the LED. Micro-Raman spectra were obtained from the top and the bottom surface of each sample. Three-way analysis of variance (α=0.05) was used for data analysis.Results: Top surface DC values were significantly higher than bottom surface in each material irrespective of the light-curing unit (P<0.05). LED produced significantly higher DC values than the QTH with all three materials (P<0.05). Helioseal Opaque showed significantly lower DC values than Helioseal Clear (P<0.05). DC values for Delton and Helioseal Clear were comparable (P>0.05).Conclusion: Higher DC is achieved with the LED with less exposure time compared with the conventional QTH at top and bottom surfaces of the three fissure sealants, although a lower conversion may be expected in opaque materials.

Effect of cyclic loading and an intermediate material on microtensile bond strengths of a dual-cure resin cement to dentin resin-coated with all-in-one adhesives

2012-03-05

Abstract: Background/purpose: The purpose of this in vitro study was to evaluate the effects of mechanical loading and an intermediate material on microtensile bond-strengths (μTBSs) of four all-in-one adhesives and a total-etching adhesive system to dentin.Materials and methods: Dentin surfaces of sound human third molars were exposed and treated with Danville Experimental (Danville Materials), G Bond (GC), Clearfil S3 Bond (Kuraray), AdheSE One (Vivadent), and Prelude total-etch (Danville Materials). Dual-curable resin (Multicore; Vivadent) build-ups were created with and without the use of Prelude Dual/Self Cure Link (Danville Materials). Two subgroups were created (with and without mechanical-loading: 5 × 104[cycles]; 50 N at 0.2 Hz). After storage at 37°C for 1 week, the μTBS test was performed. Data were calculated (MPa) and statistically analyzed (multivariate analysis of variance and Scheffe’s tests).Results: Pre-test failure was observed, and no data were obtained from groups in the absence of Prelude Dual/Self Cure Link, except for the Prelude total-etch group. Prelude total-etch provided significantly higher μTBSs to dentin than did the other adhesives (P < 0.05). Bond strengths of all tested adhesives were significantly reduced upon application of the loading regimen (P < 0.05). Clearfil S3 Bond and G Bond provided significantly higher μTBSs to dentin than AdheSE One and the experimental adhesive (P < 0.05).Conclusion: Mechanical loading significantly decreased the adhesive performance, and Prelude Dual/Self Cure Link increased it for all-in-one adhesives when used with a dual-curable resin.

Comparison of imaging characteristics of Digora fmx and Digora Optime storage phosphor plate systems

Erinç Önem, Elif Soğur, B. Güniz Baksi — 2012-03-05

Abstract: Background/purpose: The aim of this study was to compare the physical and psychophysical characteristics of a new generation of the Digora storage phosphor plate (SPP) system [Digora Optime (Soredex, Helsinki, Finland)] with its previous version [Digora fmx (Soredex, Helsinki, Finland)].Materials and methods: Radiographs of an aluminum test object with a pattern of holes that varied in depth and diameter were exposed to 65 kVp and 10 mA for nine different time settings ranging from a minimum (0.05 seconds) to a maximum (3.2 seconds) using the Digora Optime and Digora fmx SPP systems. For each system, pixel-intensity (the mean gray value) measurements, contrast resolution, and exposure range were determined and compared. In addition, a perceptibility curve test was used to compare the psychophysical properties of the two SPP systems. Repeated-measures of analysis of variance and paired t tests were used to compare the mean gray values and perceptible number of details at each exposure level (P = 0.05). The average measured intraclass correlation coefficient (AMICC) was used to compare inter-rater agreement for the number of perceived details.Results: The mean gray level output of fmx images was higher, whereas the contrast was lower than Optime images at all exposure levels (P < 0.05). Images obtained with the Optime system achieved the best contrast at a lower exposure than that of the fmx images. Digora Optime operated over a wide range of exposures; however, the fmx showed a narrower dynamic range. The number of details perceived on Optime images was significantly higher than that obtained on the fmx images at all exposure levels (P < 0.05). Agreement among observers in terms of the number of perceived details was excellent, with the AMICC ranging from 0.845–0.889.Conclusion: Digora Optime achieved the best contrast at a lower exposure and demonstrated a better dose response. In addition, the perceptibility of low-contrast details was significantly higher for Digora Optime at a wide range of exposures.

Development of a diagnostic algorithm in periodontal disease and identification of genetic expression patterns: A preliminary report

2012-02-22

Abstract: Background/purpose: To identify genetic expression patterns that can be used to define an appropriate diagnostic algorithm of clinical use in periodontal disease.Materials and methods: Total RNA was extracted from 13 samples corresponding to normal human gingiva (NHG) and human gingiva affected by periodontal disease (PDHG). A comprehensive gene expression analysis was carried out by microarray analysis using Affymetrix Human Genome U133 plus 2.0 oligonucleotide arrays.Results: Sixty-six probe sets (genes and expressed sequence tags – EST) overexpressed in all samples of one of the comparison groups, were used for the diagnostic algorithm. All samples, including an independent test sample, were correctly classified as normal or periodontally affected using the diagnostic algorithm. In addition, 2596 genes/EST were upregulated and 1542 genes/EST were downregulated in PDHG, with numerous gene functions impaired in PDHG, especially those related to the immune response, cell-cell junctions, and extracellular matrix remodeling.Conclusion: Our study reveals differential gene expression profiles in NHG and PDHG. The proposed diagnostic algorithm could have clinical usefulness for differential diagnosis in periodontal disease.

Tissue reaction surrounding miniscrews for orthodontic anchorage: An animal experiment

2012-03-05

Abstract: Background/purpose: Nowadays, mini-implant anchorage is incorporated for achieving a variety of orthodontic treatment goals. However, when a miniscrew is located in the interdental area, potential root contact may lead to miniscrew mobility or even failure. Therefore, miniscrew/root contact and possible tissue responses, including root repair, were histologically investigated in the current study.Materials and methods: Eight miniscrews were surgically placed in a single dog mandible. Among these, four miniscrews (experimental group) were intentionally placed in contact with a root and then retained for different time durations, three (control group) were also intentionally placed in contact with a root but were immediately removed after insertion, and one was placed without root contact and was retained for 24 weeks. The animal was sacrificed after 24 weeks.Results and conclusions: (1) Tissue surrounding roots damaged by a miniscrew showed a significant inflammatory response. (2) Root resorption was occasionally observed after 3 weeks following insertion of a miniscrew even if the miniscrew was not in direct contact with the root. (3) Root repair was noted with a cementoblast lining along the resorption surface at as early as 3 weeks after miniscrew insertion. Alveolar bone filled in the lesion when the root damage was large so that the contour of the alveolar bone followed that of the damaged root, with the width of the periodontal ligament space being maintained. (4) Stable miniscrews were mainly those which did not contact adjacent roots, and for which the surrounding tissue showed only a small inflammatory response with some extent of direct bone contact around the miniscrew. On the contrary, most of the failed miniscrews were those which had direct contact with adjacent roots, and which exhibited severe tissue inflammation and were covered by thick layers of soft tissue. Failure was detected 3 weeks after insertion. Surprisingly, the epithelial lining surrounding the miniscrews might not have spontaneously resolved 6 weeks after screw removal. Persistent infection in the sinus tract was noted, and this would require attention.

Prevalence of and risk factors for musculoskeletal complaints among Taiwanese dentists

2012-02-22

Abstract: Background/purpose: The prevalence of musculoskeletal disorders (MSDs) was investigated among dentists in Taiwan, and risk factors for MSDs were evaluated for symptoms in different parts of the body.Materials and methods: The Nordic musculoskeletal questionnaire modified by the Taiwan Institute of Occupational Safety and Health was completed by 197 dentists (146 males and 51 females) from the members of three groups: the Association of Oral and Maxillofacial Surgeons (n = 33), the Association of Family Dentistry (n = 55), and the Taichung County Dental Association (n = 109). Reported symptoms were compared by means of a Chi-square test according to various risk factors.Results: More than half of the respondents had experienced symptoms in the shoulders (75%), neck (72%), and lower back (66%) in the year before the survey. The three parts of the body with lower prevalence (13–15%) of trouble were hips/thighs/buttocks, knees, and ankles/feet. Seven percent of respondents indicated no trouble in any part of their bodies. The prevalence of trouble in the neck increased when the number of days worked per week increased. Risk factors (p 178 cm, and having a mean working time of >10 min/patient for the elbows; being <36 years old, having <11 years of experience, and having a mean time for forward bending or using a handpiece/scaler per patient for the wrists/hands; working 7 d/wk for the lower back and knees; having a patient load of >20 patients/d and being >35 years old for the hips/thighs/buttocks; and a having mean working time of >48 h/wk for the lower back.Conclusion: The participating Taiwanese dentists seemed to suffer a high prevalence of MSDs, especially of the shoulders, neck, and lower back. There were various associated factors and correlations with MSDs in each part of the body.

The Collum angle of the maxillary central incisors in patients with different types of malocclusion

Yen-Wen Shen, Jui-Ting Hsu, Yi-Hui Wang, Heng-Li Huang, Lih-Jyh Fuh — 2012-02-22

Abstract: Background/purpose: The Collum angle (the supplementary angle of the crown-root angle) of the maxillary central incisors is extremely important for patients who are undergoing orthodontic treatment and who are to receive an implant restoration. However, there is no report on the Collum angle in Taiwanese. Therefore, the purpose of this study was to evaluate the Collum angle of the maxillary central incisors in Taiwanese patients with different types of malocclusion.Materials and methods: This study collected 124 samples of lateral cephalometric radiographs (38 radiographs from male patients and 86 from female patients). The age of sampled patients ranged 8–58 (mean, 19.9) years. Samples were divided into four groups according to the malocclusion type, and the Collum angle of the maxillary central incisors in each group was measured. A one-way ANOVA and the Scheffe test were used to compare whether or not the angle differed among the groups.Results: The average value of the Collum angle was 6.1° ± 5.2° for class-I malocclusions, 5.3° ± 4.2° for class-II division-I malocclusions, 10.6° ± 4.4° for class-II division-2 malocclusions, and 5.6° ± 5.1° for class-III malocclusions. A statistical analysis showed that the Collum angle of the maxillary central incisors for patients with class-II division-2 malocclusions significantly exceeded values in the other three groups.Conclusion: Compared to groups with other malocclusion types, the Collum angle of natural teeth for patients with class-II division-2 malocclusions was the greatest.

Dental caries and body mass index in a sample of 12-year-old eastern Turkish children

Kenan Cantekin, Taskin Gurbuz, Sezer Demirbuga, Tevfik Demirci, Gülsüm Duruk — 2012-03-05

Abstract: Background/purpose: The objective of the present study was to investigate the possible correlation between the body mass index (BMI) and dental caries among 12-year-old Turkish children.Materials and methods: The clinical study was performed on 224 12-year-old children at the Department of Pediatric Dentistry, Atatürk University, Erzurum, Turkey, to determine their dental caries and malnutrition status. To assess the nutritional status, the weight for age, height for age, and BMI were determined. The BMI status was categorized into four groups: 1 (underweight), 2 (normal weight), 3 (overweight), and 4 (obese). The occurrence of dental caries was determined using the decayed, missing, and filled teeth (DMFT) index.Results: Respective mean DMFT values for BMI-1, BMI-2, BMI-3, and BMI-4 were 1.44, 1.47, 1.81, and 2.33, respectively. There were significant differences between BMI-1 and BMI-4 (P = 0.019, r2 = 0.73) and between BMI-2 and BMI-4 (P = 0.022, r2 = 0.72) values.Conclusion: Paedodontics should consider the relationship between patients’ body composition and oral health, in order to provide the best service for pediatric patients, and should advice parents on oral-health promotion.

Clinical characterization of mouth opening among Mexican adolescents and young adults

2012-03-05

Abstract: Objective: To estimate two mouth opening (MO) assessments in a sample of apparently healthy Mexican adolescents and young adults, in the context of age and sex.Material and Methods: We examined in a cross-sectional study 254 subjects 14 to 24 years old to ascertain the maximum MO (MMO) and the assisted maximum MO (AMMO) using a ruler (Scala®). The measured mouth opening capacities were not adjusted by adding the vertical overlap between arches (overbite). Clinical oral examinations were undertaken by four standardized examiners. Statistical analyses included Student's t-test and linear regression modeling.Results: Mean age was 16.76 ± 2.39 years and 53% of the 254 participants were men. Overall mean MMO was 46.61 ± 7.37 mm (minimum 28, maximum 69), and AMMO was 49.48 ± 6.59 mm (minimum 32, maximum 75). Age had no identifiable relationship with MMO or AMMO but we observed that the mean difference between men and women in MMO and AMMO was 3.29 mm (P < 0.001) and 3.16 mm (P < 0.001), respectively.Conclusions: Besides finding that Mexican young males have higher mean maximum mouth opening than females, the present study offers some of the first anthropometric outline relevant to orthodontic, prosthetic/prosthodontic developmental calculations for an important parameter of normal mandible/maxilla function among Hispanics/Mexicans.

Phenytoin- and amlodipine-induced gingival overgrowth

Ching-Wen Chang, Chih-Jen Yang, Yu-Lin Lai — 2012-03-19

Abstract: Drug-induced gingival overgrowth is an adverse event associated with three types of drugs, i.e., anticonvulsants, immunosuppressants, and calcium-channel blockers. It was shown that the combined use of an immunosuppressant (cyclosporine) and a calcium-channel blocker increases the prevalence and severity of gingival overgrowth. However, few reports discussed the effects of the combination of an anticonvulsant (phenytoin) and a calcium-channel blocker (amlodipine). In this case report, we present an epilepsy patient who was using both phenytoin and amlodipine, which caused extensive gingival overgrowth. After periodontal treatment and a gingivectomy, the gingival overgrowth was significantly reduced. A postoperative drug-substitution regimen and intensive professional care ensured a stable result 1 year after surgery.