bluuebunny/crossref_metadata_2025 huggingface dataset:
Damage of the Hertwig's epithelial root sheath: effect upon root growth after autotransplantation of teeth in monkeys
Authors: Andreasen J. O. , Kristerson L. , Andreasen F. M.
Published: April 2006

Abstract The effect of damage to the Hertwig's epithelial root sheath (HERS) during autotransplantation was examined in 12 green vervet monkeys. During the transplantation of permanent incisor tooth germs, either one‐half or the entire root sheath was amputated or a contusion injury made to the root sheath. Transplanted incisors served as controls, where attempts were made not to injure the HERS. After an observation period of 9 months, a histologic examination of the transplanted teeth was performed. This examination showed variations in root growth among the various experimental groups. Thus, arrested root formation with ingrowth of bone from the base of the socket was the normal finding in the groups where either the entire HERS was amputated or contused. The group with partial amputation of HERS showed formation of a new but diminutive root. The control group showed teeth with normal root formation. The development of pulp necrosis usually led to complete or almost complete arrest of root formation irrespective of group. The present study indicated that the HERS can function normally subsequent to trauma elicited by surgical separation of the follicle and the post‐transplantation disturbances in nutrition. Furthermore, a regenerative potential appeared to exist in this structure, even if just a fraction of it was left intact.
Comparative debridement study between hand and sonic instrumentation of the root canal
Authors: Goldberg Fernando , Snares Ilson , Massone Enrique Joaquin , Scares Iara Maria
Published: April 2006

Abstract The cleaning efficiency of hand and sonic instrumentation with MM Sonic 3000 in 60 single‐rooted human straight teeth was evaluated using light and scanning electron microscopy. The root canals were instrumented with K‐type files and Shaper Sonic files, respectively, and manually irrigated with 1 % sodium hypochlorite. The results showed no statistically significant difference between hand and sonic instrumentation. In both groups a smear layer, untouched predentin and pulp tissue debris were generally observed.
Apical periodontitis and resoprtion of the root canal wall
Authors: Delzangles Bernard
Published: April 2006

Abstract The incidence, extent and distribution of root canal wall resorption were studied in 100 extracted human teeth with chronic periapical lesions. Scanning electron microscopy showed that intracanal dentin resorption had occurred in all teeth. There was no difference between teeth with apical granulomas or radicular cysts. The resorption process was generalized and intensive in the apical third of the root canal, whereas the resorption lacunae were more irregularly spread in the middle and cervical thirds of the canal. Intracanal dentin resorption should be taken into account during endodontic treatment, especially when establishing the apical limit of root canal instrumentation.
In vivo sealing ability of calcium hydroxide‐containing root canal sealers
Authors: Barnett Frederic , Trope Martin , Rooney Jane , Tronstad Leif
Published: April 2006

Abstract It was the purpose of this study to determine the sealing ability of 2 commercially available calcium hydroxide‐containing root canal sealers, CRCS and Sealapex. One hundred sixty single‐rooted human teeth were used. The clinical crowns were removed and the roots were cleaned mechanically and by immersion for 24 h in 5% sodium hypochlorite. The root canals were then instrumented to size 80 at the apical foramen and the roots were sterilized by γ‐radiation. Under aseptic conditions the root canals were filled with a gutta‐percha master cone size 70 and Sealapex (48 roots), CRCS (48 roots), and a zinc oxide‐eugenol type sealer, Roth 801 (50 roots). The coronal aspects of the root canals were then sealed with zinc oxide‐eugenol cement. In order to bring the roots and root filling materials in contact with tissue and tissue fluids, the roots were implanted subcutaneously in rabbits for 90 days and 1 year. Leakage as demonstrated by penetration of India ink was evaluated using a stereomicroscope. The best results were obtained with CRCS. Significantly less leakage occurred with both calcium hydroxide‐containing sealers than with the traditional zinc oxide‐eugenol sealer.
Endodontic effects of root planing in humans
Authors: Wong Raymond , Hirsch Robert S. , Clarke Nigel G.
Published: April 2006

Abstract Although the deliberate removal of cementum by root planing remains part of periodontal therapy, its scientific basis is under challenge. A potentially harmful effect of root planing is the exposure of dentinal tubules to the oral environment; this study investigated the short‐term endodontic effects of root planing in humans. Ten teeth with significant loss of periodontal attachment had one proximal surface root planed; the other proximal surface was not root planed. After 10‐14 days, the teeth were extracted and processed for light microscopic and SEM examination. Hypersensitivity to thermal stimuli was reported by 4 subjects after root planing. Chronic pulpitis was found in 3 pulps adjacent to the area of root planing. Bacterial penetration of dentin was observed, although the depth of penetration was less than reported by others. The results indicated that previous perceptions of the beneficial role of root planing in periodontal therapy require reconsideration.
Image analysis of endodontic radiographs: digital subtraction and quantitative densitometry
Authors: Brstavik Dag , Farrants George , Wahl Trond , Kerekes Kasmer
Published: April 2006

Abstract In this study computerized image analysis procedures were applied to endodontic radiographs. Kontron IBAS 2000 is a commercially available image analysis system with processing routines applicable to radiograph digitizing and transformations. The system was evaluated for: its ability to harmonize blackening and contrast in endodontic radiographs; its ability to compensate for angulation distortion of sequential exposures of individual teeth; its potential for application of digital subtraction methods; and its use in automated gray‐level analyses of diseased and healthy bone areas in endodontic radiographs. The Kontron IBAS 2000 system proved suitable for all applications. However, the specificity of the subtraction procedure was limited by some inherent problems in the harmonization of blackening and in the subtraction process itself. On the other hand, automated gray level measurements proved to be a robust method for unbiased and quantitative assessment of healing of apical periodontitis.
Estimated radiation risks associated with endodontic radiography
Authors: Danforth Robert A. , Torabinejad Mahmeud
Published: April 2006

Abstract Endodontic patients are sometimes concerned about the risks of tumors or cataracts from radiation exposure during root canal therapy. By using established dose and risk information, we calculated the extent of these risks. The chance of getting leukemia from an endodontic x‐ray survey using 90 kVp was found to be 1 in 7.69 million, the same as the risk of dying from cancer from smoking 0.94 cigarettes or from an auto accident when driving 3.7 km. Risk of thyroid gland neoplasia was 1 in 667,000 (smoking 11.6 cigarettes, driving 45 km) and risk of salivary gland neoplasia 1 in 1.35 million (smoking 5.4 cigarettes, driving 21.1 km). Use of 70 kVp radiography reduced these risks only slightly. To receive the threshold dose to eyes to produce cataract changes, a patient would have to undergo 10,900 endodontic surveys.
Transmission electron microscopy of supraalveolar periodontal healing of auto‐ and allotransplanted teeth in monkeys
Authors: Schwartz Ole , Groisman Mario , Attström Rolf , Andreasen Jens Ove
Published: April 2006

Abstract An ultrastructural study of the supra‐alveolar periodontal healing of auto‐ and allotransplanted teeth was performed in 4 immunologically unmatched green Vervet monkeys. Eight mature incisors were either auto‐ or allotransplanted. Non‐transplanted adjacent incisors served as controls. Prior to transplantation the teeth were endodontically treated extraorally. Eight weeks after transplantation, biopsies including part of the tooth and the adjacent supra‐alveolar tissues were taken, fixed, decalcified and processed for electron microscopy. A thin electron dense layer covered the root surface of the autotransplanted teeth. Most collagen fibres inserted into this electron‐dense border, as well as into the underlying cementum. A similar relationship between the fibres and root surface was found in controls. On the allotransplanted teeth a layer of electron‐dense granular material covered the root surface in the supra‐alveolar area. Collagen fibres inserting into the electron‐dense border were frequently observed. Fibroblasts were the predominant cell type in the connective tissue adjacent to all transplanted teeth. In autotransplants 2 morphotypes of fibroblasts were observed: 1) cells with dilated endoplasmic reticulum and swollen mitochondria; and 2) cells with normal characteristics of protein synthesis and secretion. The fibroblasts of the allografts were predominantly cells with dilated endoplasmic reticulum and swollen mitochondria. The results indicated some similarities in the healing between the root surface and connective tissue in the supra‐alveolar portion of the roots of auto‐ and allotransplanted teeth.
Periapical bacterial plaque in teeth refractory to endodontic treatment
Authors: Tronstad Leif , Barnett Frederic , Cervone Frank
Published: April 2006

Abstract It has recently been found that bacteria are able to survive and maintain an infectious disease process in periapical lesions of nonvital teeth. The purpose of this study was to examine the surfaces of root tips removed during surgical‐endodontic treatment for the presence of microorganisms. A full thickness flap was reflected under strict surgical asepsis and the periapical lesions were enucleated and removed. About 2‐3 mm of the root was cut off, rinsed in sterile saline and placed in 10% neutral‐buffered formalin. Upon fixation, the root tips were dehydrated, air‐dried and given an electrically conducting coat of gold in a vacuum evaporator. The root tips were then studied in a Jeol, JSM‐U3 scanning electron microscope, usually operated at 20 kV. The root surfaces were covered with soft tissue, except at the apex of the roots, where a continuous, smooth and structureless coating was seen, apparently adjacent to the apical foramen. At higher magnification a variety of bacterial forms were recognized in the smooth coating. A bacterial plaque was observed in irregularities of the surfaces between fiber bundles and cells and in crypts and holes. The bacteria were held together by an extracellular material and the plaque was dominated by cocci and rods. Fibrillar forms were recognized as well, often with cocci attached to their surfaces.
The role of immune cytokines in the pathogenesis of periapical lesions
Authors: Stashenko Philip
Published: April 2006

Abstract Bacterial infection of the dental pulp results in pulpal destruction, and subsequently stimulates an inflammatory cell response and destruction of bone in the periapex. Bacterial components, including lipopolysaccharides, induce the production of many polypeptide mediators, or cytokines, by inflammatory cells. These cytokines, which include macrophage‐derived interleukin‐1 beta, interleukin‐1 alpha and tumor necrosis factor, and lymphocyte‐derived lymphotoxin, have been shown to potently stimulate bone resorption and to inhibit reparative bone formation in vitro and in vivo. This review presents the hypothesis that immune cytokines play a major role in the pathogenesis of periapical lesions.
Developmental anomaly of permanent teeth related to traumatic injury
Authors: Kaufman Arieh Y. , Keila Senia , Wasersprung David , Dayan Dan
Published: April 2006

Abstract A case is presented where a 4‐year‐old girl was injured in an automobile accident. The dental injury, intrusive luxation of the maxillary deciduous incisors, seemed unimportant at the time, since the child was in critical condition. The situation was first evaluated 5 years later, when the child was referred for treatment of an apical periodontitis originating from the right central incisor. The present case reflects several important aspects that were overlooked at the time of injury: the potential of intruded luxated deciduous teeth to cause developmental anomalies to the permanent dentition; the necessity of a longer follow‐up period to detect such anomalies; and the need to develop effective treatment methods.
Mandibular first premolar with three root canals
Authors: Hülsmann Michael
Published: April 2006

Abstract This report presents a case of endodontic treatment of a mandibular first premolar with 3 root canals and a review of the literature concerning root canal anatomy of lower premolars. It is stressed that, even in teeth with a low frequency of abnormal root canal anatomy, the possibility of additional root canals has to be considered in the clinical and radiographic examination of the patient.
Effect of brief storage in ATP solution on periodontal healing after replantation of teeth in rats
Authors: Zanetta‐Barbosa Darceny , Perri de Carvalho Antonio César
Published: April 2006

Abstract ATP solution seems to increase calcium absorption when applied both to dentin and to the pulp before the application of calcium hydroxide. In this study, the effects of a brief storage of teeth in ATP or saline solution before replantation were compared. The right maxillary incisors of 80 male albino rats were extracted and immersed, either directly or after 25 min air‐drying, in ATP or saline solution and then replanted. Eight animals in each group were killed 5, 10, 30, 60 and 90 d after replantation and the teeth were examined histologically. The histometric analysis revealed significant differences between the saline‐ and ATP‐treated group. More new cementum or cementum‐like tissue was deposited over the radicular surface in the ATP‐treated teeth. More root surface area was resorbed and not repaired by new cementum in the saline group and more total root surface was not resorbed or resorbed and repaired in the ATP‐treated group. Based on these findings, it seems reasonable to conclude that brief storage of teeth in ATP solution before replantation may have improved the healing of replanted teeth in rats.
Vertical root fracture and dentin deformation in curved roots: the influence of spreader design
Authors: Murgel Carlos Alberto Ferreira , Walton Richard E.
Published: April 2006

Abstract The effect of lateral condensation using different tapered spreaders was evaluated. Curved mesiobuccal roots of maxillary molars were step‐back prepared. Strain gauges applied to the root surfaces measured dentin deformation (distortion) during controlled lateral condensation with either fine finger or D 11 spreaders. After obturation, roots were cross sectioned and analyzed under the stereomicroscope to detect the presence and pattern of fractures. The results showed no statistical difference between spreader designs as to mean distortion and the incidence of fractures; however several specimens in the D11 group showed high root distortion measurements. When fractures occurred, there were no consistent patterns of fracture in either spreader group. In conclusion, although there were no significant differences in mean deformation or fracture incidence in curved roots between the spreaders, the roots showing high deformation readings in the D11 group may be more susceptible to future vertical root fractures.
SEM study of surface architecture of gutta‐percha cones
Authors: Goldberg F. , Massone E. J. , Pruskin E. , Zmener O.
Published: April 2006

Abstract The apical third of 60 standardized, gutta‐percha cones obtained from six different manufacturers were analyzed by scanning electron microscopy. Despite the fact that the majority of the commercial gutta‐percha cones showed rather uniform and smooth surfaces, some displayed morphologic variations such as gross protuberances or deeply cratered areas containing numerous free or entrapped crystal‐like particles.
Effects of the penetration of a root canal filling material into the mandibular canal. 2. Changes in the alveolar nerve tissue
Authors: Kawakami T. , Nakamura C. , Eda S.
Published: April 2006

Abstract The root canal filling material “Vitapex” (Neo Dental Chemical Products Co., Tokyo), made of calcium hydroxide and iodoform with the addition of silicone oil, was experimentally injected into the mandibular canals of dogs, and its effect on the alveolar nerve tissue was examined by light and electron microscopy. No change was observed as long as the injected paste did not come into direct contact with the nerve, but tissue damage was found at sites of direct contact. After removal of degenerated nerve debris by macrophages and Schwann cells, the persisting external membranes or “Schwann tubes” appeared to provide a scaffolding for axonal regeneration and Schwann cell proliferation.
Surface architecture of a low‐temperature thermoplasticized gutta‐percha
Authors: Goldberg F. , Zmener O. , Massone E. , Pruskin E. , Basrani E.
Published: April 2006

Abstract The surface characteristics of two Ultrafil materials, Regular set (RS) and Firm set (FS) were analyzed by scanning electron microscopy (SEM). The samples of Ultrafil were obtained from both RS and FS cannules which were pre‐heated to 70°C. Another RS and FS samples were obtained at room temperature from un‐heated cannules. Samples of standard gutta‐percha points obtained from the same manufacturer were studied for comparative purposes. RS samples obtained from pre‐heated and un‐heated cannules exhibited rough surfaces containing randomly distributed crystal‐like structures. Heated and un‐heated FS samples featured smoother surfaces with fewer crystal‐like structures. The gutta‐percha points also exhibited smooth surfaces and absence of crystal‐like structures. The consequence of the possible release of these structures from Ultrafil in a biological system is discussed.
A study of endodontically apexified teeth
Authors: Kleier Donald J. , Barr Elizabeth S.
Published: April 2006

Abstract This study was undertaken to determine the clinical and radiographic success of calcium hydroxide apexification in a group of 48 patients requiring endodontic therapy because of pulpal necrosis prior to root‐end closure. The study examined tooth number, etiology of pulpal necrosis, age, sex, size of root‐end opening, size of radiolucency, crown discoloration, interappointment symptoms, and total treatment time from initial instrumentation to completion of apexification. Apexification required an average of 1 year ± 7 months. A statistically significant relationship was found between: the presence of a radiolucency and development of interappointment symptoms (p<0.04); and the size of apex opening and development of interappointment symptoms (p<0.02). If symptoms did develop, apexification was delayed an additional 5 months when compared to patients who did not have symptoms. Calcium hydroxide apexification was found to be statistically highly successful regardless of the clinical variables encountered.
Retrograde root filling with composite and a dentin‐bonding agent. 1
Authors: Rud J. , Munksgaard E. C. , Andreasen J. O. , Rud V. , Asmussen E.
Published: April 2006

Abstract A method is described, by which retrograde root filling with a composite resin can be performed. The cavity design is a slightly concave dissection of the apical part of the root, which is treated with the bonding agent Gluma followed by an application of Retroplast. Retroplast is a chemically curable composite containing silver for radiopacity and aerosil to obtain a suitable consistency. Endodontically treated teeth with a eugenol‐containing root canal sealer did not affect the strength of the bond between Retroplast and apical dentin. A tight seal between the composite and the cavity surface was observed by light and SEM microscopy, and histology of tissue surrounding fillings placed in monkeys revealed absence of inflammatory cells around the filling and a close contact between filling and fibro‐blasts with collagenous fibers. In some cases, cementum and Sharpey's fibers formed in contact with the filling. Fillings placed in humans performed successfully in most cases, and the main causes of failure were either inadequate hemostasis during filling, or root fracture unnoticed by the time of filling. The retrograde technique promises a new treatment principle, with a root canal effectively sealed and the periapical ligament restored after apicoectomy.
Efficacy of Ledermix paste in eliminating Staphylococcus aureus from infected dentinal tubules in vitro
Authors: Heling Ilana , Pecht Mordehay
Published: April 2006

Abstract The efficacy of Ledermix paste in disinfection of dentinal tubules was studied in a model developed by Haapasalo and Ørstavik with some modifications. Ledermix and 3% Tetra‐cycline in a hydrous base were effective in reducing the amount of Staphylococcus aureus in dentinal tubules after 7 days of incubation and also after recontamination. They were not effective after 24 h.
Endodontology – epidemiologic considerations
Authors: Eriksen Harald M.
Published: April 2006

Abstract The limited information available from endodontic epidemiologic research indicates an increase in prevalence of apical periodontitis with increasing age. Furthermore, apical periodontitis seems mainly to be present in connection with already endodontically treated teeth. This finding should be of particular concern since there is a discrepancy between the quality and results of endodontic therapy performed in general practice compared with the results obtained in specialty clinics. Pulpitis and acute apical periodontitis are main reasons for seeking emergency treatment and affect many people. Dental trauma frequently involving the dentin/pulp organ are likewise prevalent, affecting 30% of children and adolescents. Most information available regarding endodontic treatment is derived from well‐controlled clinical studies performed by specialists. Epidemiologic data should be considered a necessary complement to this source of knowledge regarding etiologic factors and proper treatment procedures in order to improve the results of endodontic practice.
Permeability of normal versus carious dentin
Authors: Pashley E. L , Talman R. , Horner J. A. , Pashley D. H.
Published: April 2006

Abstract Although a number of reports have been published demonstrating that carious dentin is less permeable than normal dentin, these reports have been qualitative rather than quantitative. The purpose of this in vitro study was to apply a quantitative technique to the study of the permeability of carious human teeth before and after excavation, before and after removal of the smear layer and before and after preparation of a control cavity of similar size and depth in normal dentin subjected to the same measurements, for comparative purposes. Dentin permeability was measured as a hydraulic conductance. The permeability values measured at each step in the protocol were expressed as a percent of the maximum permeability of both cavities, permitting each tooth to serve as its own control. Carious lesions exhibited a slight degree of permeability (2.3 ± 0.6% of controls) which remained unchanged after excavation of the lesions. Removal of the smear layer in the excavated carious lesions increased the permeability significantly to 6.9 ± 3.2%. Preparation of a control cavity of the same area and depth increased the permeability slightly. Removal of its smear layer increased the permeability of the dentin 91%. These results confirm previous qualitative studies that carious dentin, even after excavation and removal of the smear layer has a very low permeability.
Scanning electron microscopy of bacteria in the apical part of root canals in permanent teeth with periapical lesions
Authors: Molven Olav , Olsen Ingar , Kerekes Kasmer
Published: April 2006

Abstract The most apical 2 mm of the root canals of periapically diseased roots were examined for microorganisms by scanning electron microscopy (SEM). Bacteria in this area were observed in 10 out of 12 (83.3%) cases. The two remaining cases exhibited bacteria more coronally, with tissue remnants between the bacterial front and the apical foramen. Rod‐shaped bacteria dominated, but filaments, spirochetes and cocci were also seen. Cocci and rods sometimes formed micro‐colonies. Occasionally, cocci were seen attached to filaments forming “corn‐cob”‐like structures. Deposits resembling bacterial plaque were also found inside the root canal. SEM is useful for studying microbial topography of the apical root canal.
Efficacy of different irrigation methods and concentrations of root canal irrigation solutions on bacteria in the root canal
Authors: Briseño M. B. M. , Wirth R. , Hamm G. , Standhartfnger W.
Published: April 2006

Abstract The effectiveness of two different root canal irrigating solutions, each in two different concentrations or formulations, with two different irrigation methods was compared in vitro by means of bacterial survival determinations. 75 human root canals were enlarged, sterilized and inoculated with a mixed culture of Escherichia coli and Streptococcus mutatis. After inoculation, the root canals were irrigated either manually or with an ultrasonic‐device for equal times (20s) with the same amount (5 ml) of sodium hypochlorite (1% and 2%). Fokalhydran I and Fokalhydran II. Sodium hypochlorite (1% and 2%) was used in a 1:100 dilution. Fokalhydran 1 and II were used in a 1:10 dilution. In the sodium hypochlorite group, the 1% concentration applied with a syringe proved to be most effective against Escherichia coli and Streptococcus mutans. The least effective concentration and application method against both bacteria species was obtained with 2% NaOCL and ultrasonics. Against Escherichia coli and Streptococcus mutans, a significantly lower effectiveness was found with 2% NaOCL applied with ultrasonics with respect to the rest of the sodium hypochlorite group. Fokalhydran I was significantly better than Fokalhydran 11 against Escherichia coli. However, no significant differences could be seen against Streptococcus mutans within this group.
Treatment of crown fractured incisors with laminate veneer restorations. An experimental study
Authors: Andreasen Frances M. , Flügge Erik , Daugaard‐Jensen Jette , Munksgaard E. Christian
Published: April 2006

Abstract A method is described by which crown fractured incisors are restored with cast ceramic (Dicor) laminate veneers after initial treatment with either reattachment of the original crown fragment with a dentin bonding agent, with a composite resin build‐up or no treatment (i.e. the veneer alone is used to restore the incisal edge). In order to elucidate the effect of the fragment/composite‐tooth bonding interface on fracture strength of the restored teeth, the fracture strengths of the various treatment groups were compared to that of intact teeth supplied with Dicor laminate veneers. In an experimental investigation using central and lateral incisors from sheep, it was found that fracture strength (16.6 ±4.2 MPa) equal to that of intact incisors (16.1 ± 2.6 MPa) could be achieved using laminate veneers made of porcelain on fractured teeth whose crown fragments were reattached using a dentin bonding agent (5). In the present investigation, using the same experimental model but using cast ceramic (Dicor) laminate veneers, the fracture strength of the restored incisors was significantly increased (21.0 ± 3.7 MPa), exceeding that of intact teeth. The fracture strength of intact teeth was also exceeded in veneered incisors which were initially restored with a conventional composite resin build‐up (20.2±5.6 MPa). However, the greatest fracture strength (28.2 ±8.9 MPa) was achieved when a Dicor laminate veneer alone was used to restore the fractured ineisal edge. The strength was equivalent to that of intact teeth supplied with Dicor veneers (26.7 ± 6.3 MPa). While fracture strengths of teeth which were initially restored by fragment reattachment and then supplied with veneers exceeded that of intact teeth when veneer preparation was limited to enamel, they were reduced to the half of (hat of intact teeth (i.e. the same strength as teeth initially restored by fragment reattachment and no veneering) if the preparation extended into dentin. In the present experimental model, ii would appear that laminate veneers alone might be used to restore lost incisal edges of crown fractured anterior teeth.
Treatment of root fracture with accompanying resorption using cermet cement
Authors: Lui Joo Loon
Published: April 2006

Abstract A method of treating an apical root fracture with accompanying resorption at the junction of the fracture fragments using glass‐cermet cement is described. Endodontically. the material had previously been used for repair of lateral resorptive root defects and retrograde root fillings. Complete bone regeneration was observed three years post‐operatively following treatment of the root fracture in the conventional manner. The various advantages of glass‐cermet cement as a root filling material used in the technique described are discussed.
Dental materials for posterior restorations
Authors: Rykke Morten
Published: April 2006

Abstract Assessment of the quality of dental restorations by the Ryge system is described. Generally, the quality of dental restorations is shown to be dependent on the technique sensitivity of the restorative material as well as the skill and experience of the dentist. Concerning biocompatibility, adverse reactions related to amalgam restorations are unlikely or scarce, due to small amounts of released mercury. Resin based restorative materials contain a large number of organic compounds and, as such, the toxic and allergenic potentials are unknown. Gold and ceramics turn out to be the most biotolerable dental materials. Based on studies on longevity, data indicate that the median age of amalgam restorations is 10‐12 years, of gold castings 13‐14 years and more, and of composite restorations 4 years. Data on longevity of ceramic restorations are sparse. Secondary caries appears to be the most frequent cause for replacement of the different restorations, followed by marginal degradation. Secondary caries account for more failures among the resin based restorations than among amalgam. Reviewing the literature, it appears that amalgam is the best and most economic dental material for routine posterior restorations with reasonable durability. Gold is recommended for complex restorations. Resin based composites may be limited to small restorations where cosmetics is the main aspect, as wear and recurrent caries are main problems. Ceramic restorations comprise aesthetic restorations with excellent bio‐compatibility, however, data on longevity and marginal adaptation are not encouraging.
A case of progressive external root resorption treated with surgical exposure and composite restoration
Authors: Isidor F. , Stokholm R.
Published: April 2006

Abstract Progressive external, root resorption was observed apical to the alveolar crest on the buccal surface of a tooth. The area of root resorption was surgically exposed. To gain access to the root resorption cavity osteoectomy was performed. The soft tissue in the resorption cavity was removed and a composite filling (Retroplast) was placed in the cavity using a dentine bonding system (Gluma). The pulp was removed and the root canal was obturated with gutta‐percha points and root canal sealer (AHL26). Eight months after treatment no further root resorption was observed. Increased pocket depth and slight bleeding on probing in the area of resorption were evident.
Reasons for and incidence of tooth mortality in a Swedish population
Authors: Eckerbom M. , Magnusson T. , Martinsson T.
Published: April 2006

Abstract Longitudinal studies on tooth mortality are rare but the reasons for tooth mortality have been studied by several authors. The aims of this investigation were to study the reasons for and incidence of tooth mortality in an earlier described Swedish population of 200 patients on two occasions with an interval of 5‐7 years, and to see if the reasons for extractions were correlated to posts, crowns or endodontic status, respectively. 197 (4.0%) of the 4889 teeth registered at the first examination were lost during the interval. 65 (33%) of the lost teeth were endodontically treated. 44 (68%) of these were registered as having one or more root with a root‐filling ending more than 2 mm from the apex and 29 (45%) were judged to have an improper seal. In 93 of the 197 lost teeth it was possible to find the reason for extraction from the patient chart. Based on distribution of selected variables, these 93 teeth seemed to be representative of the whole group of 197. It was concluded that tooth losses were evenly distributed in the different age‐groups and that above all molars but also premolars were lost more often than teeth in the frontal region. Furthermore, endodontically treated teeth were lost more often than other teeth and the quality of the root‐filling affected the risk for losses while crowned teeth did not run a higher risk of being lost than teeth without crowns. Finally, it was found that caries, including pulpitis and apical periodontitis, was the main reason for tooth extractions.
Histologic evaluation of three endodontic instrument/preparation techniques
Authors: Zuolo M. L. , Walton R. E , Imura N.
Published: April 2006

Abstract 33 curved canals were prepared to quantify both the increase in canal area and predentin removal in the apical region. Compared were three different file designs/instrumentation techniques, that is “stepback” with K‐flex file, “balanced force” with Flex‐R file, and the Canal Master system. Following canal preparation and histological processing, cross‐sections at 1 and 3 mm levels were examined using the Bioquant image analysis system. Results showed that, at the 3 mm leve, the mean increase in canal area and predentin removal showed no statistically significant difference (p> 0.05) between the techniques. At 1 mm. the step‐back technique (with K‐flex files) resulted in a significant increase in canal area and greater predentin removal than did the “balanced forces” (with Flex‐R files) or the Canal Master system. However, although there were statistical differences, the actual differences were small; these may not translate to clinically significant differences in the 3 techniques.
Spirochaetes in oral infections
Authors: Dahle Ulf R. , Tronstad Leif , Olsen Ingar
Published: April 2006

Abstract Oral Spirochaetes, which are small‐, medium‐ or large‐sized, include species of the genus Treponema, many of which have not yet been cultured. They are found in root canal infections, pericoronitis, gingivitis and periodontitis, constituting up to 10% of the flora in endodontic abscesses, 30% in acute necrotizing ulcerative gingivitis, and 36% in advanced marginal periodontitis. The strong proteolytic activity of these organisms probably make them causes of infection rather than consequences. Being able to penetrate tissue, they bring their enzymes, metabolic products, and endotoxins, in direct contact with target cells. This may perturb essential functions of host cells and immunoglobulins. Enzyme activities may also help fulfil the complex growth requirements of Spirochaetes in vivo. Reaction between infected periodontal tissue and monoclonal antibodies to Treponema pallidum has suggested that uncharacterized pathogen‐related oral spirochaetes have surface structures and functions analogue to this well recognized pathogen. This warrants a more intensified search for the role of spirochaetes in oral infections.
Investigation of the children referred to a dental hospital with avulsed permanent incisor teeth
Authors: Mackie I. C. , Worthington H.
Published: April 2006

Abstract The management of children referred to a dental hospital because of avulsed permanent incisor teeth was considered in a retrospective study. The group consisted of 49 children between the ages of 6 and 14 years. Most of the children (60%) had their avulsed teeth stored dry while only 7% had them stored in milk, and 19% in saliva. Following avulsion the majority of the children attended a dental surgeon or general hospital. Twenty‐three children contacted health care personnel within 30 minutes but only 13 had their teeth replanted in this time period. Thirty‐six children had 46 incisors replanted. No relationship was demonstrated between the place or personnel who replanted the teeth, and a successful outcome.
Bonding of enamel‐dentin crown fragments after crown fracture. An experimental study using bonding agents
Authors: Andreasen F. M. , Steinhardt U. , Bllle M. , Munksgaard E. C.
Published: April 2006

Abstract Previous experimental studies into the use of dentin bonding agents for reattachment of enamel‐dentin crown fragments have demonstrated fracture strength about 50–60% of that of intact teeth. In the clinic this has been reflected in the frequent need of repeated bonding of the treated incisors due to refracture. Recently newer bonding agents have been developed which can bond equally well with enamel and dentin. Employing the same experimental model, these bonding agents (All‐Bond 2, Scotchbond MP) were used to reattach crown fragments to the remaining portion of sheep incisors. Loading of teeth bonded with these agents in an Instron testing machine at a speed of 1 mm/min demonstrated similar fracture strengths as those previously achieved with Gluma, Scotchbond 2 or Tenure. A second study was carried out whereby fragments were bonded with Scotchbond MP and loaded at various speeds. The results demonstrated that the fracture strength decreased exponentially with increased loading speed. By extrapolation, it was concluded that the strength was nil at a loading speed of approximately 2 m/min. It was concluded that the weak link in the bond between tooth fragment and remaining tooth structure is the bonding resin. Theoretically, a resin which is slightly elastic might act as a shock absorber to withstand functional stress. However, studies carried out with resins of varying moduli of elasticity gave disappointing results probably due to their low flexural strength. It is concluded on basis of previous and present results that reattachment with a bonding resin of the enamel dentin crown fragment after crown fracture is a realistic alternative to composite resin build‐up although only half the strength of intact teeth is achieved.
Implants in children: a case report
Authors: Mackie I. C. , Quayle A. A.
Published: April 2006

Abstract A post‐crowned, root‐filled tooth in a 13‐year‐old child which is retraumatised resulting in palatal fracture of the root often necessitates removal of the root. The future treatment plan involves appropriate space management and restorative treatment. In this instance the root was retained in order to preserve alveolar bone until the patient was old enough for an implant
Variations in stroke rate and loading using hand sonic or ultrasonic instrumentation
Authors: Lumley P. J. , Walmsley A. D. , Harrington E. , Marquis P. M.
Published: April 2006

Abstract An in vitro model system was developed to investigate the stroke rate and loading during hand, sonic, or ultrasonic instrumentation. The model system consisted of a mandibular molar tooth attached to a strain gauge and interface to a computer. Ten clinicians instrumented the distal canal of lower molar teeth. Stroke rates used and loads applied were measured using different sized files with the three different preparation techniques. There was no significant difference in stroke rates between different file sizes (p>0.05) within the same generator, however, stroke rate for hand was significantly slower than for sonic or ultrasonic (p<0.01). Loading of the canal wall rose with increase in file size which was significant for hand (p<0.01) and sonic (p<0.05) but not ultrasonic (p>0.05). There was a tendency for loading to be higher with hand instrumentation, this however was not significant (p>0.05).
Treatment of root‐fractured maxillary incisor with Thermafil obturator
Authors: Gençoǧlu Nimet
Published: April 2006

Abstract This case report describes the treatment of a maxillary left central incisor with intra‐alveolar horizontal root fracture in the middle of the root. The pulp of the coronal segment was necrotic and endodontic treatment was performed. Instrumentation of the root canal through the fracture line was carried out and the tooth was obturated with Thermafil in order to bring about a union of the fragments. At the 24‐month follow up examination the tooth was functionally and esthetically normal. Radiographically no pathosis was evident in the periapical or fracture areas.
Partial pulpotomy in crown‐fractured permanent incisor with hyperplastic pulpitis: a case report
Authors: Çalişkan M. K. , Sepetçioḡlu F.
Published: April 2006

Abstract Hyperplastic pulpitis, which is regarded as one type of asymptomatic irreversible pulpitis, occurs usually in young teeth where pulps are exposed by caries or trauma. If apices are mature, root canal therapy is recommended. In this case, the success of partial pulpotomy in a crown‐fractured permanent incisor with hyperplastic pulpitis, which had been contaminated with oral microflora for six months is reported.
The sealing ability of IBM® with the addition of hydroxyapatite as a retrograde root filling
Authors: Owadally I. D. , Chong B. S. , Ford T. R. Pitt , Watson T. F.
Published: April 2006

Abstract The effect of adding 10% & 20% hydroxyapatite (HAP) on the sealing ability of IRM (Intermediate Restorative Material) when used as a retrograde root filling was assessed using a confocal optical microscope with a fluorescent dye. This was compared with another reinforced zinc‐oxide eugenol cement (Kalzinol), ethoxybenzoic acid (EBA) cement and amalgam. The root canals of 70 extracted human single‐rooted teeth were prepared and filled with gutta‐percha and sealer. All the teeth were apicected, retrograde cavities were prepared, and then divided into groups of 10 teeth each and filled with the test materials. A remaining group of 10 teeth were used as controls. The extent of dye penetration around IRM, IRM + 10% and IRM + 20% HAP was not significantly different. There was also no difference in the extent of dye penetration between EBA cement and IRM. However the sealing ability of both these materials was better than Kalzinol and amalgam. All the amalgam retro‐ grade root fillings leaked, exhibiting the poorest sealing ability. Dye penetrated into the root canals of all the positive controls whereas there was no dye penetration in the negative controls. The addition of 10% or 20% hydroxyapatite did not adversely affect the good sealing ability of IRM.
Partial pulpotomy in young permanent teeth with deep carious lesions
Authors: Mejàre I. , Cvek M.
Published: April 2006

Abstract The material comprised 37 young posterior teeth with deep carious lesions and exposed pulps, treated with partial pulpotomy and dressed with calcium hydroxide. The teeth were divided into two groups. Group 1 consisted of 31 teeth with no clinical or radiographic symptoms before treatment, Group 2 of 6 teeth with temporary pain, widened periodontal space periapically and/or productive osteitis, i.e. increased density of the surrounding alveolar bone. After an observation time of 24 to 140 months (x̄= 56 months), healing had occurred in 29 of 31 teeth in Group 1 (93.5%) and in 4 of 6 teeth in Group 2. It was concluded that the present, as well as previously reported results indicate that partial pulpotomy may be an adequate treatment for young permanent molars with a carious exposure, although more studies are needed before the treatment can be recommended for routine clinical use.
Repair of untreated root fracture: a case report
Authors: Tziafas Dimitrios , Margelos Ioannis
Published: April 2006

Abstract A case is presented in which an untreated root fracture in a maxillary central incisor of an adult male was found radiographically 10 years after injury. The tooth was removed and the area of the root corresponding to the fracture line was examined by SEM while the remaining tooth was processed for decalcified sections. Calcification of the coronal pulp associated with extensive tissue atrophy and normal pulp tissue apically was observed. Two barriers composed of dent in al and cemental hard tissue were present apically in the coronal fragment and in the fracture line.
Effect of probe design on the suitability of laser Doppler flowmetry in vitality testing of human teeth
Authors: Ingólfsson Ægir Rafn , Tronstad Leif , Hersh Elliot V. , Riva Charles E.
Published: April 2006

Abstract The aim of this investigation was to study the influence of probe design on the signal output from the dental pulp in experiments with laser Doppler flowmetry (LDF). Eighteen patients 14 to 39 years of age were examined. Recordings were made from a maxillary and a mandibular central incisor and a maxillary canine with an infrared laser Doppler flowmetry. The radiographic appearance of the tested teeth was within normal limits and all teeth responded normally to electric pulp testing (EFT). Five configurations of probes were used. Each probe had 3 fibers arranged in a triangle. One fiber carried the laser light to the pulp tissue and 2 fibers carried the backscattered light to the detector giving the signal output. The diameter of each of the 3 fibers in the probe was 200 μm except in 1 probe where the diameter of the fibers was 125 μm. The distance between the 3 fibers in the triangular arrangement in each probe was 250, 500, 800, 1000, and 1500 μm. A special rubber base splint was used to hold the probe in place on the buccal surface of the tested teeth. The output signals from the LDF were fed into an analog printer and a lap top computer where all calculations were done. The probe with the largest separation of the fibers produced significantly higher output signals from the maxillary and mandibular incisors than the other probes. The same probe also produced significantly higher output signals than the smaller probes from the maxillary canine with the exception of the 200/800 probe. The output signals were significantly higher from the mandibular incisor than from the maxillary incisor and canine. Consecutive recordings with the LDF from the maxillary incisor in 5 patients within 1 hour gave coefficient of variation from 7.9% to 10.3% in output signals. The results of this study showed that all 5 experimental probes gave output signals indicative of blood flow in the dental pulp and the probe with the largest separation of fibers seemed to be the most suitable one under the experimental conditions used. It appeared to be possible to make reproducible recordings from the pulp of the teeth under the experimental conditions used.
Influence of endodontic materials on the bonding of glass ionomer cement to dentin
Authors: Capurro M. A. , Herrera C. L. , Macchi R. L.
Published: April 2006

Abstract We assessed the bond strength of a glass ionomer cement to dentin that had been in contact with different materials. Flat dentin surfaces in freshly extracted human teeth were covered for 48 h with a 1 mm layer of a variety of materials that are used for temporary filling or root canal sealing. The products were mechanically removed and a glass ionomer cement cylindrical specimen bonded to the dentin surface. After 7‐days immersion in 37° C water the tensile bond strength was tested. The results were compared with those on dentin surfaces not in contact with any endodontic material. The statistical analysis showed that none of the materials used interfered with the bonding of the glass ionomer to dentin.