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Notes: Abstract The tissue solvent capacity of a 2% stabilized sodium hypochlorite solution (Milton®) and a commercial calcium hydroxide solution (Calasept®) was examined under in vitro conditions where autolyzed human pulp fragments weighing approximately 0.0065 g were immersed in these solutions at 37°C for periods of up to 10 days. It appeared that sodium hypochlorite was able to dissolve half the volume of pulp tissue within 1 h and the remaining tissue after 2–2 1/2 h. Calcium hydroxide dissolved half the pulp volume within 2 h, whereas it took 1 week for the remaining tissue to dissolve. These findings support the use of sodium hypochlorite as an irrigation solution during canal preparation and calcium hydroxide as a canal dressing for the purpose of creating a canal free of pulp remnants before root filling.

Notes: Abstract A method is described, by which the fracture strength of bonded, previously fractured incisors can be measured. The study employed incisors from sheep, which could be obtained in suitable numbers and with limited variation in size. The incisors were fractured parallel to the incisal edge. The mean fracture area + SD of central incisors was 8.45 ± 0.89 mm2 and of lateral incisors 6.50 ± 0.64 mm2. The enamel area constituted about 30% of the total fracture area. Acid etching of the enamel and bonding of the fractures with an unfilled resin yielded a fracture strength, which was approximately 38% of the fracture strength of fractured teeth restored with acid etching of enamel, Gluma treatment of dentin and bonding with the unfilled resin. Teeth restored in this way, but using the dentin bonding agent Tenure or Scotchbond2 instead of Gluma, exhibited mean fracture strengths which were not significantly different from that obtained when Gluma was employed as the bonding agent. The mean fracture strength by using one of the three bonding agents in combination with acid etching of enamel was about 8 MPa, which is approximately 50% of the fracture strength of intact teeth.

Notes: Abstract Intentional replantation of teeth appears to be a suitable model for examining the etiology and pathogenesis of root resorption elicited after traumatic dental injury. A histomorphometric analysis of root resorption developed with this model is described. An analysis of the accuracy and precision of the method in replanted monkey incisors has demonstrated that the method is usually reliable in revealing the extent and type of root resorption. In some experimental circumstances, however, where the pulp status was not controlled by endodontic therapy, a large intra- and interanimal variation was found in the extent of root resorption. Apart from a relation to tooth maturation and tooth type (incisors versus molars), this variation was primarily caused by haphazard occurrence and extent of inflammatory resorption. Based on an analysis of a series of experimental replantation studies, the following guidelines for experimental design seem appropriate: 1) selection of teeth according to identical tooth development and pulp status (i.e. intact, extirpated or root-canal-treated); 2) use of a standardized extraction procedure; 3) consideration of the type of teeth included (i.e. molars vs. incisors), unless paired experiments are planned or the experimental design includes an equal number of incisors and molars allotted to the different experimental groups; 4) side differences (right vs. left side) are apparently of no or minor importance; 5) sex differences are apparently of no or minor importance; 6) an individual proneness to resorption is apparently of no or minor importance, which means that more than one tooth can be used in each animal. The experimental design thus does not dictate the use of paired (i.e. homologous) teeth. However, as a matter of safety, when small differences in healing are expected, paired observations should be used.

Notes: 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.

Notes: Abstract A material of 322 patients with 400 avulsed and replanted permanent teeth were followed prospectively in the period from 1965 to 1988 (mean observation period=5.1 yrs). The age of the patients at the time of replantation ranged from 5 to 52 yrs (mean =13.7 yrs and median =11.0 yrs). Standardized patient records were used through the entire period in order to obtain valid data concerning the extent of injury and treatment provided. At the follow–up period, pulpal and periodontal healing were monitored by clinical examination, mobility testing and standardized radio–graphic controls. Thirty–two of the replanted teeth (8%) showed pulpal healing. When related to teeth with incomplete root formation, where pulpal revascularization was anticipated (n = 94) the frequency of pulpal healing was 34%. Periodontal ligament healing (i.e. with no evidence of external root resorption) was found in 96 teeth (24%). Gingival healing was found in 371 teeth (93%). During the observation period, 119 teeth (30%) were extracted. Tooth loss was slightly more frequent in teeth with incomplete root formation at the time of replantation than in teeth with completed root formation.

Notes: Abstract 400 avulsed and replanted permanent teeth were examined for periodontal ligament (PDL) healing, using standardized radiographic and clinical examination procedures (i.e. percussion test and mobility test). The effect of various clinical factors was examined, such as age and sex of the patient, type of tooth replanted, presence of crown fracture or bone fracture, stage of root development (including apical diameter and length of the pulp), type and length of extra-alveolar storage, clinical contamination of the root surface, type of root surface cleansing procedure, type and length of splinting period and antibiotic therapy. Surface resorption was generally diagnosed after 12 months; while inflammatory resorption and replacement resorption (ankylosis) were usually observed after 1 month and 12 months respectively. Most resorptive processes were diagnosed within the first 2–3 years. However, although rarely, even after 5 and 10 years new resorptive processes could be diagnosed. A univariate statistical analysis of 272 teeth revealed 9 factors significantly related to PDL healing. A subsequent multivariate analysis revealed that the following 4 factors had the strongest impact upon PDL healing, in descending order of significance: Stage of root development; length of the dry extra-alveolar storage period; immediate replantation and length of the wet period (saliva or saline storage). Nonphysiological storage, such as homemade saline and sterilizing solutions (chloramine and alcohol) always led to root resorption. Storage in tap water for more than 20 minutes usually led to root resorption. The common denominator for all these factors related to PDL healing appears to be survival of the PDL cells along the root surface. Based on these findings, immediate replantation is recommended irrespective of stage of root development.

Notes: Abstract –  According to treatment type, root-fractured teeth with pulp necrosis or exposed pulps were divided into five groups, group 1: 17 teeth in which the root canal of the coronal fragment only was filled with gutta-percha (GP); group 2: seven teeth in which the root canals of the coronal and apical fragments were both filled with GP; group 3: 19 teeth in which the coronal fragment was filled with GP and the apical fragment was surgically removed; group 4: 68 teeth where the root canal of the coronal fragment was treated with calcium hydroxide and subsequently filled with GP; and group 5: five vital teeth with root and concomitant crown fractures in which the exposed pulps were treated by partial pulpotomy. The frequency of periodontal healing was 76% in group 1, zero in group 2, 68% in group 3 and 86% in group 4. Compared with groups 1 and 2 combined, healing in group 4 was significantly more frequent. In groups 1, 2 and 4, failures occurred significantly more often in teeth showing overfilling, i.e. protrusion of GP into the space between the fragments, compared with teeth without overfilling. All five teeth in group 5 showed healing. It was concluded that root canal filling with GP of the coronal fragment only, with or without surgical removal of the apical fragment, can be successful in selected cases. Treatment of the root canal with calcium hydroxide followed by GP filling appears to be the treatment of choice in root-fractured non-vital teeth. Partial pulpotomy of exposed pulps in five teeth showed results similar to root-unfractured teeth with pulp exposure treated with this technique.

Notes: Abstract –  This retrospective study consisted of 400 root-fractured, splinted or non-splinted incisors in young individuals aged 7–17 years (mean = 11.5 ± 2.7 SD) who were treated in the period 1959–1995 at the Department of Pediatric Dentistry, Eastman Dental Institute, Stockholm. Four hundred of these root fractures were diagnosed at the time of injury; and 344 teeth were splinted with either cap-splints, orthodontic appliances, bonded metal wires, proximal bonding with composite resin or bonding with a Kevlar® or glass fiber splint. In 56 teeth, no splinting was carried out for various reasons. In the present study, only pre-injury and injury factors were analyzed. In a second study, treatment variables will be analyzed. The average observation period was 3.1 years ± 2.6 SD. The clinical and radiographic findings showed that 120 teeth out of 400 teeth (30%) had healed by hard tissue fusion of the fragments. Interposition of periodontal ligament (PDL) and bone between fragments was found in 22 teeth (5%), whereas interposition of PDL alone was found in 170 teeth (43%). Finally, non-healing, with pulp necrosis and inflammatory changes between fragments, was seen in 88 teeth (22%). In a univariate and multivariate stratified analysis, a series of clinical factors were analyzed for their relation to the healing outcome with respect to pulp healing vs. pulp necrosis and type of healing (hard tissue vs. interposition of bone and/or PDL or pulp necrosis). Young age, immature root formation and positive pulp sensibility at the time of injury were found to be significantly and positively related to both pulpal healing and hard tissue repair of the fracture. The same applied to concussion or subluxation (i.e. no displacement) of the coronal fragment compared to extrusion or lateral luxation (i.e. displacement). Furthermore, no mobility vs. mobility of the coronal fragment. Healing was progressively worsened with increased millimeter diastasis between fragments. Sex was a significant factor, as girls showed more frequent hard tissue healing than boys. This relationship could possibly be explained by the fact that girls experienced trauma at an earlier age (i.e. with more immature root formation) and their traumas were of a less severe nature. Thus, the pre-injury or injury factors which had the greatest influence upon healing (i.e. whether hard tissue fusion or pulp necrosis) were: age, stage of root development (i.e. the size of the pulpal lumen at the fracture site) and mobility of the coronal fragment, dislocation of the coronal fragment and diastasis between fragments (i.e. rupture or stretching of the pulp at the fracture site).

Notes: Abstract Traumatic dental injuries are very frequent in both the primary and permanent dentition. As these often imply combined injury to both the pulp and periodontium, a variety of healing complications may arise, such as pulp necrosis, pulp canal obliteration, root resorption and loss of marginal attachment. Furthermore, trauma in the primary dentition can be transmitted to the permanent successors, leading to a variety of developmental disturbances. The analysis of the etiology of these complications has hitherto been seriously hampered by a lack of agreement on the registration of the extent of injury to the tooth and its supporting structures (i.e. trauma classification), lack of agreement on the definition of healing complications and shortcomings in the statistical analysis of follow-up studies of traumatized primary and permanent teeth. The consequences of these shortcomings are described with respect to the evaluation of prognosis of various types of trauma. Suggestions are made for data collection and analysis of future trauma studies which should enable the identification of factors determining the outcome of traumatic dental injuries. Through a perusal of recent dental literature, various trauma entities and treatment procedures are evaluated. Furthermore, areas are outlined where present knowledge does not allow rational treatment selection or prognosis evaluation.

Notes: Abstract –  This is the second part of a retrospective study of 400 root-fractured permanent incisors. In this article, the effect of various treatment procedures is analyzed. Treatment delay, i.e. treatment later than 24 h after injury, did not change the root fracture healing pattern, healing with hard tissue between fragments (HH1), interposition of bone and/or periodontal ligament (PDL) or pulp necrosis (NEC). When initial displacement did not exceed 1 mm, optimal repositioning appeared to significantly enhance both the likelihood of pulpal healing and hard tissue repair (HH1). Significant differences in healing were found among the different splinting techniques. The lowest frequency of healing was found with cap splints and the highest with fiberglass or Kevlar® splints. The latter splinting procedure showed almost the same healing result as non-splinting. Comparison between non-splinting and splinting for non-displaced teeth was found to reveal no benefit from splinting. With respect to root fractures with displacement, too few cases were available for analysis. No beneficial effect of splinting periods greater than 4 weeks could be demonstrated. The administration of antibiotics had the paradoxical effect of promoting both HH1 and NEC. No explanation could be found. It was concluded that, optimal repositioning seems to favor healing. Furthermore, the chosen splinting method appears to be related to healing of root fractures, with a preference to pulp healing and healing fusion of fragments to a certain flexibility of the splint and possibly also non-traumatogenic splint application. Splinting for more than 4 weeks was not found to influence the healing pattern. A certain treatment delay (a few days) appears not to result in inferior healing. The role of antibiotics upon fracture healing is questionable.