Zafer C. Cehreli

Regenerative Endodontic Treatment (Revascularization) of Immature Necrotic Molars Medicated with Calcium Hydroxide: A Case Series

INTRODUCTION Revascularization is an emerging regenerative treatment protocol with little published data available in immature molar teeth. The present case series demonstrates the outcome of revascularization treatment with intracanal medicament of calcium hydroxide in immature necrotic molars. METHODS Immature necrotic permanent first molars (n = 6) of patients 8-11 years old were treated by a revascularization protocol that used 2.5% NaOCl irrigation, medication with calcium hydroxide placed in the coronal third of the root canals, induction of apical bleeding, and coronal sealing with white mineral trioxide aggregate. Among the treated teeth, 4 molars had undergone prior root canal instrumentation by the referring dentists. National Institutes of Health Image-J program with TurboReg plug-in was used for standardization of the radiographs and to determine the increase in root length and root width. RESULTS After a follow-up period of 10 months, all teeth demonstrated radiographic evidence of complete periapical healing, progressive thickening of dentinal walls, and continued apical development in the absence of clinical symptoms. Two uninstrumented molars showed a positive response to cold testing at 9 months. CONCLUSIONS On the basis of a follow-up period of 10 months, the present cases demonstrate a favorable outcome of the revascularization procedure in immature necrotic molars by using calcium hydroxide medication in the coronal third of the root canals.

Dentin moisture conditions affect the adhesion of root canal sealers.

INTRODUCTION The purpose of this study was to evaluate the effects of intraradicular moisture conditions on the push-out bond strength of root canal sealers. METHODS Eighty root canals were prepared using rotary instruments and, thereafter, were assigned to 4 groups with respect to the moisture condition tested: (1) ethanol (dry): excess distilled water was removed with paper points followed by dehydration with 95% ethanol, (2) paper points: the canals were blot dried with paper points with the last one appearing dry, (3) moist: the canals were dried with low vacuum by using a Luer adapter for 5 seconds followed by 1 paper point for 1 second, and (4) wet: the canals remained totally flooded. The roots were further divided into 4 subgroups according to the sealer used: (1) AH Plus (Dentsply-Tulsa Dental, Tulsa, OK), (2) iRoot SP (Innovative BioCeramix Inc, Vancouver, Canada), (3) MTA Fillapex (Angelus Indústria de Produtos Odontológicos S/A, Londrina, Brasil), and (4) Epiphany (Pentron Clinical Technologies, Wallingford, CT). Five 1-mm-thick slices were obtained from each root sample (n = 25 slices/group). Bond strengths of the test materials to root canal dentin were measured using a push-out test setup at a cross-head speed of 1 mm/min. The data were analyzed statistically by two-way analysis of variance and Tukey tests at P = .05. RESULTS Irrespective of the moisture conditions, iRoot SP displayed the highest bond strength to root dentin. Statistical ranking of bond strength values was as follows: iRoot SP > AH Plus > Epiphany ≥ MTA Fillapex. The sealers displayed their highest and lowest bond strengths under moist (3) and wet (4) conditions, respectively. CONCLUSIONS The degree of residual moisture significantly affects the adhesion of root canal sealers to radicular dentin. For the tested sealers, it may be advantageous to leave canals slightly moist before filling.

Surface tension of root canal irrigants.

The aim of this study was to evaluate the surface tension values of established and potential endodontic irrigants to which a surface active agent had not been added. Additionally, Cetredixine, a surfactant-containing 0.2% chlorhexidine gluconate solution, was included in the measurements. Surface tension measurements were performed using the ring method on a DuNouy tensiometer at a standard room temperature. Ringers solution, saline solution, and distilled water had the highest surface tension values, whereas those of NaOCl (2.5% and 5%) and 17% EDTA were relatively low. Two anesthetic solutions, Ultracaine and Citanest, demonstrated values similar to NaOCl and EDTA, although a statistically significant difference was found between all solutions tested. Cetredixin displayed the lowest surface tension. A low surface tension agent should penetrate tubules better.

A morphological and micro-tensile bond strength evaluation of a single-bottle adhesive to caries-affected human dentine after four different caries removal techniques

OBJECTIVES This study evaluated the influence of different caries removal techniques (conventional bur; chemomechanical removal/Carisolv()-MediTeam; a sonic preparation system/SonicsysMicro-Kavo and air abrasion/PrepStar-Danville Engineering) on microtensile bond strength to caries-affected human dentine. METHODS Occlusal surfaces of extracted human permanent third molars with coronal dentine caries extending approximately halfway through the dentine was ground perpendicular to the long axis of the tooth to expose a flat surface of normal dentine surrounding the carious lesion with laser fluorescence values of approximately 30 (DIAGNODent), KaVo). Carious lesions were excavated with one of the four techniques until laser fluorescence values decreased to 15 in the center of the lesions. An ethanol-based dentine adhesive (Single Bond, 3M) was used to bond composite resin (P60, 3M) to the substrate. Vertical slices (n=11/group), approximately 0.8 mm thick were made through the caries-affected portions of each tooth, perpendicular to the bonding surface. Specimens were subjected to tensile stress at a crosshead speed of 1 mm/min. Data were analyzed by Kruskal-Wallis test. SEM investigation was performed for the qualitative evaluation of resin-dentine hybridization. RESULTS The microtensile bond strengths were as follows (mean+/-SD in MPa): 6.4+/-5.3 (bur), 8.4+/-3.3 (Carisolv), 8.5+/-5.9 (Sonicsys Micro), and 8.8+/-8.8 (air abrasion). Statistical analysis did not show significant differences between any of the treatment modalities (p=0.160). Tensile fracture was cohesive within caries-affected dentine in all specimens. CONCLUSIONS The four different caries removal techniques used within this study did not influence the bond strength of the tested dentine adhesive to caries-affected human dentine.

Traumatic intrusion of primary teeth and its effects on the permanent successors: A clinical follow-up study

OBJECTIVE Owing to the anatomic proximity between the root of the primary tooth and its permanent successor, trauma to primary dentition may cause developmental disturbances in unerupted permanent teeth. STUDY DESIGN This report presents the findings of a prospective 7-year study examining developmental disturbances of permanent teeth attributed to intrusive injury of their primary predecessors based on initial patient records and clinical observation. Intrusive injuries were diagnosed and grouped according to World Health Organization classifications, as modified by Andreasen et al. RESULTS A total of 78 children (aged 12-48 months) presenting with intrusive trauma to 138 primary incisors were available for follow-up examinations. The most frequently intruded primary teeth were maxillary incisors (93.47%), with the right central primary incisor representing 41.3% of all intruded teeth. In 23 patients, 36 teeth were scheduled for extraction during the first visit. During the course of follow-up, 41 of the remaining teeth exhibited post-traumatic consequences, including pulp necrosis (78.0%), internal and/or external root resorption (14.6%), ankylosis (4.9%), and obliteration of the pulp canal (2.5%). In 74 permanent successors (53.6%), >or=1 of the following developmental disturbances were observed: enamel hypoplasia (28.3%), crown and/or root deformation (16.7%), and ectopic eruption (16.7%). CONCLUSION There was no significant correlation between age of intrusion and frequency of subsequent developmental disturbances (P > .05).

Calcium ion diffusion from mineral trioxide aggregate through simulated root resorption defects.

The purpose of this study was to investigate the diffusion of calcium ions (Ca+2) through exposed dentinal tubules following intracanal application of mineral trioxide aggregate (MTA). Fifty-two single-rooted teeth were instrumented using 2.5% sodium hypochlorite for irrigation between each file size. Thereafter, standardized defects were created on the root surfaces so as to mimic external root resorption. The root canals and external defects received a final irrigation of 17% ethylenediaminetetraacetic acid and distilled water. MTA powder was then mixed with saline and placed into the canals. All root surfaces except the cavities were sealed with two coats of varnish. Teeth with unfilled canals (n = 26) served as controls. The teeth were immersed in saline after which the release of Ca+2 from the defects into the saline was measured at 1, 3, 7, 14, and 28 days. The results showed diffusion of Ca+2 through the defects in the dentin in MTA-filled roots with a significant increase in concentration within time.

Chemical and Ultramorphologic Effects of Ethylenediaminetetraacetic Acid and Sodium Hypochlorite in Young and Old Root Canal Dentin

OBJECTIVES The objectives of this study were to evaluate and compare the time-dependent chemical and ultramorphologic effects of ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) in young and old dentin. METHODS Sixty-four teeth scheduled for extraction were collected from young (<30 years) and old (>60 years) patients. In 48 teeth, the dentin was reduced to a powder state and treated with EDTA or EDTA + NaOCl for 1 and 10 minutes, respectively. X-ray diffraction analysis was used to determine the changes in the composition of dentin through dissolution of hydroxyapatite (HAp). In the remaining teeth (n = 16), the root canals were prepared, bisected, and subjected to the same time-dependent treatment regimens. The changes in the number and area of dentinal tubules were calculated by image analysis. The data were analyzed statistically by paired t test and one-way analysis of variance, followed by Tukey honestly significant difference test at P = .05. RESULTS In both young and old dentin, EDTA significantly decreased the HAp intensity at 1 and 10 minutes, whereas EDTA + NaOCl only decreased that of old dentin at 10 minutes. Pair-wise comparisons revealed that in old dentin, the reduction in HAp intensity after treatment with EDTA and EDTA + NaOCl was significantly greater at 10 minutes than at 1 minute, whereas in young dentin, a significant decrease was only observed in the EDTA/10-minute subgroup. Compared with their 1-minute counterparts, 10-minute treatment with EDTA + NaOCl significantly increased the tubular diameter and tubular area of old dentin. In young dentin, the tubular area and diameter values were not affected by treatment time (P > .05). CONCLUSIONS In young root dentin, 10-minute treatment with EDTA + NaOCl does not significantly alter the chemical and ultramorphologic structure and thus appears to be unnecessary. In old dentin, extended treatment time with EDTA + NaOCl should be avoided owing to excessive demineralization and erosion. In both types of dentin, EDTA was not effective in complete removal of the smear layer.

Effects of a Nonrinse Conditioner and 17% Ethylenediaminetetraacetic Acid on the Etch Pattern of Intact Human Permanent Enamel

The purpose of this study was to evaluate the effects of 2 new acid-etching solutions, nonrinse conditioner (NRC) and 17% ethylenediaminetetraacetic acid (EDTA), on enamel surface morphology, and to compare the new solutions with traditional 37% phosphoric acid. The effect of prolonged etching time was also investigated. The buccal surfaces of 80 extracted third molars were etched with one of the 3 acids for 15, 30, or 60 seconds. The central regions of the specimens were examined with a scanning electron microscope. Shorter etching time with phosphoric acid resulted in a relatively smooth enamel surface compared with longer treatments. Irrespective of treatment time, NRC produced an aprismatic etch pattern, which suggested a potentially retentive morphological character. EDTA treatment had the least effect of all etchants tested.

Antibacterial Activity of Fifth-Generation Dentin Bonding Systems

Past concepts that the pulp does not become infected until an actual carious exposure takes place have been challenged. The antibacterial effects of the dentin bonding systems Single Bond, Prime&Bond NT, and Excite were evaluated using the bacteria Streptococcus mutans ATCC 25175, Streptococcus intermedius, Lactobacillus acidophilus, Prevotella oris, Prevotella bivia, Prevotella denticola, Porphyromonas gingivalis, Porphyromonas endodontalis, and Clostridium ramosum with a disk diffusion method. Chlorhexidine (0.2%) was used as a positive control. After incubation zones of inhibited bacterial growth were measured. Prime&Bond NT showed growth inhibition for all bacterial strains. Lactobacillus acidophilus and Streptococcus mutans were remarkably resistant to Single Bond, whereas EX produced no inhibitory effect on Porphyromonas endodontalis, although the adhesive produced the maximum halo inhibition to Streptococcus mutans (15+/-1 mm), showing an antibacterial effect closest to chlorhexidine. The variety of results obtained in this study suggest that antibacterial properties of current dentin adhesives may depend on components that are originally incorporated to promote adhesion.

Fracture resistance of tooth fragment reattachment: effects of different preparation techniques and adhesive materials

The purpose of this study was to evaluate and compare the bond strengths of experimentally fractured human tooth fragments reattached with different adhesive materials and retentive techniques in vitro. Uncomplicated crown fractures were obtained on intact human mandibular permanent incisors by applying perpendicular load to the buccal aspect of tooth crowns. Fractured teeth were randomly assigned into one of three reattachment protocols: (i) Simple reattachment, (ii) Overcontour preparation, and (iii) Internal dentin groove. The first and second groups were divided into 10 subgroups, and the third group into five subgroups (n = 10 per group) with respect to five different adhesive systems (Prime&Bond NT, Adper Single Bond II, Adper Prompt L-Pop, Clearfil S(3) Bond, G Bond) used with or without a hybrid resin composite (Z250). Restored teeth were subjected to thermal cycling, and subsequently to the same loading protocol used for fracturing intact teeth. Fracture strength after reattachment procedures was recorded as a percentage of the original fracture strength. Both type of adhesive material and placement of an intermediate layer of resin composite affected the fracture resistance (P < 0.05). The highest fracture strength recovery was obtained using the internal dentin groove technique (54 +/- 0.58%, P < 0.05), followed by the overcontour and simple reattachment protocols (49 +/- 0.58% and 32 +/- 0.82%, respectively, P < 0.05). Ultramorphological evaluation of bonded specimens revealed voids and microcracks along the adhesive interface, which might contribute to postadhesive failure.