Masticatory ability and functional tooth units in Japanese adults

Summary  The purposes of this study were (i) to examine the relationship between the number of natural teeth and the number of functional tooth units in Japanese adults, (ii) to evaluate how functional tooth units relate to subjective masticatory ability and (iii) to determine the minimum number of natural teeth and functional tooth units needed to maintain adequate self-assessed chewing function. A self-administered questionnaire was given and dental examination was conducted for 2164 residents aged 40 to 75 years. Counts were made on the number of functional tooth units of natural teeth (n-functional tooth units), the sum of natural teeth and artificial teeth on implant-supported and fixed prostheses (nif-functional tooth units) and the sum of natural teeth and artificial teeth on implant-supported, fixed and removable prostheses (total-functional tooth units). The average number of natural teeth, n-functional tooth units and nif-functional tooth units decreased with age, but these were often replaced by functional tooth units from artificial teeth on removable prostheses. Total-functional tooth units in 50–59 year old people were slightly lower compared with those in other age groups. Subjects who reported that they could chew every food item on an average had 23·4 total natural teeth, 12·6 posterior natural teeth, 7·6 n-functional tooth units, 8·6 nif-functional tooth units and 10·4 total-functional tooth units, and subjects without chewing difficulties had fewer functional tooth units from removable prostheses. Maintaining 20 and more natural teeth and at least eight nif-functional tooth units is important in reducing the likelihood of self-assessed chewing difficulties.     

An electrophysiological study of the reinnervation of reimplanted and autotransplanted teeth in the cat

There is evidence to suggest that some reimplanted and autotransplanted teeth are reinnervated, but the time-course of reinnervation and the properties and source of the reinnervating axons are not known. This reinnervation has been investigated using electrophysiological techniques in 6 adult cats. In each cat, one lower canine and three incisor teeth were extracted and immediately reimplanted. Three other lower incisor teeth were transplanted into an edentulous area. The teeth were splinted in position for 6 weeks. Bipolar electrical stimulation of 22 of the 38 successfully reimplanted or autotransplanted teeth evoked a jaw-opening reflex within 9–24 weeks of the surgery. The reflex had a raised threshold and increased latency. Twenty-four weeks after reimplantation or autotransplantation, 32 of the 38 teeth contained nerve fibres travelling in the ipsilateral inferior alveolar nerve but, compared with normal, the fibres had decreased conduction velocities and produced small amplitude compound action potentials in the teeth when stimulated. Seven of the reimplanted teeth contained nerve fibres travelling in the contralateral inferior alveolar nerve. These results suggest that reimplanted and autotransplanted teeth may be reinnervated but the axons are small in diameter, and either few in number or mainly located near to the apices of the teeth. Reimplanted teeth may be reinnervated by axons from the nerve which supplied them originally or by sprouting and ingrowth of axons from nerves supplying adjacent tissues.     

A three-dimensional evaluation of the effects of functional occlusal forces on the morphology of dental and periodontal tissues of the rat incisor

We examined the effect of function on tooth and periodontal ligament (PDL) morphology in 40 lower incisors of adult female rats. Ten teeth were exposed to occlusal hyperfunction for three months, ten to hypofunction for three weeks, ten to hypofunction for three months, while ten teeth in normal occlusion served as control. Transverse ground sections were cut at various levels perpendicular to the tooth long axis, and their distances from the apex were calculated. The outlines of the tissues were traced and fed into a computer. We plotted the measurements according to their location and fitted them by second-order polynomials. We calculated tissue volume for the proximal 18 mm of bone-embedded tooth. Hyperfunction affected tooth shape, in that it became more rounded. The volumes of the dental tissues remained unchanged, while width and volume of the cementum-bordering PDL increased. Hypofunction did not alter tooth shape, but influenced its size: After three weeks, tooth circumference decreased, and after three months, it expanded. Dentin width was reduced, with concomitant increase of pulp size. The amount of enamel diminished initially, but after three months returned to normal values. The PDL bordering enamel expanded proportionally to the duration of hypofunction. The changes in socket size reflected the total dimensional variations in the tooth and its PDL. The results demonstrate that the shape and size of growing teeth and their periodontium are influenced by functional occlusal forces.     

Reimplantation of primary tooth – case report

Abstract –  This article reports a clinical case of a primary tooth avulsion followed by dental reimplantation and endodontic treatment according to the protocol established by the Federal University of Santa Catarina for the treatment of traumatized primary teeth. A patient, 2 years and 6 months of age, MR, suffered the avulsion of tooth 61 because of a fall at school. The child was given dental assistance within 30 min, and the avulsed tooth was stored in milk during the period. After radiographic examination, the tooth was reimplanted and splinted. This procedure was performed after having obtained the mother's permission. Endodontic treatment was implemented a few days after the reimplantation because of the pulp necrosis that originated from a neurovascular bundle rupture. The endodontic treatment consisted of calcium hydroxide manipulated using glycol propylene dressings. After 12 months of treatment, the avulsed tooth presented the absence of periapical bone rarefaction in addition to a dry root canal, presenting ideal conditions for a definitive obturation. The obturation was applied using ZOE. The follow-up procedures on the obturated tooth were performed until the total eruption of the succeeding permanent tooth had been achieved, with no sequelae. Reimplantation, followed by endodontic treatment performed according to biological principles, has proven to be a good option for avulsed primary teeth.     

The effect of tooth extraction on periodontal ligament mechanoreceptors represented in the mesencephalic nucleus of the cat

When a force is applied to a tooth, mechanoreceptors in the periodontal ligament are stimulated. When teeth are extracted the remnants of the periodontal ligament break down and disappear, but it is not known what happens to the mechanoreceptor neurones that innervated it. The present study seeks to determine the effect of tooth extraction on the population of periodontal ligament mechanoreceptor neurones represented in the mesencephalic nucleus of the fifth cranial nerve. The incisor and canine teeth were extracted from adult cats; terminal experiments were performed between 7.5 months and 2 yr later. Recordings were made in the mesencephalic nucleus with microelectrodes, and neurones were identified in the inferior alveolar nerve that previously innervated the periodontal ligament of one of the extracted mandibular teeth. The majority of these neurones responded only to electrical stimuli applied to the edentulous ridge of the mandible in the area where the incisor or canine teeth had previously been. It was not possible to stimulate them mechanically, despite the use of large forces. A small number had reinnervated new soft-tissue sites. They could be mechanically stimulated and were found adjacent to the area in which the mandibular incisor and canine teeth had been. Thus the population of periodontal ligament mechanoreceptor neurones represented in the mesencephalic nucleus do not all degenerate after tooth extraction. As the majority of those still present do not appear to reinnervate new tissues in which they can be mechanically stimulated, it is unlikely that they have any functional role after tooth loss.     

The effect of normal occlusal forces on fluid movement through human dentine in vitro

Receptors inside human incisors appear to respond to stress (comparable to pressure as opposed to force) on the crown. This ability may be used to limit the stress applied to teeth or to discriminate between the hardness of objects clenched between upper and lower teeth. Here the hypothesis that these receptors are activated by fluid squeezed out of dentinal tubules when the loaded tooth is stressed was tested. Vertically compressing the crowns of extracted human teeth with loads of from 20 to 120 N, similar to those used in other studies and during natural chewing, did indeed displace fluid into the pulp. The fluid was displaced away from the crown immediately after the tooth had been loaded and moved back into the crown when the load was removed. The volume ranged from 3.5 to 22.2×10³ pl, similar to that known to stimulate single pulpal nerve fibres. Thus, normal chewing forces could displace sufficient fluid out of dentine to excite putative mechanoreceptors somewhere inside the dentine/pulp complex.     

Clinical and histopathological observation of CaO-P2O5-MgO-SiO2-CaF system glass ceramic tooth implants in monkeys

The present study was undertaken to determine the biocompatibility of a newly-developed CaO-P2O5-MgO-SiO2-CaF system glass ceramic tooth implant. Two adult male monkeys were selected and 12 weeks after extraction of M1 and P1, 8 glass ceramic teeth were implanted into alveolar bone. At 1 week after implantation, 6 teeth were allowed occlusal function, and 2 teeth were left free from occlusion as control teeth. The implants were observed for 4-12 weeks and examined histopathologically. The results were as follows: 1. Seven implanted teeth were well maintained clinically, and only one tooth was lost after 5 weeks. 2. In histopathological observation, implanted teeth were surrounded by bone, and connected by bonyankylosis. At cervix of dental implant, connective tissue as also attached firmly to implanted tooth surfaces and epithelial attachment was observed. 3. Although these implants were allowed occlusal function at an early stage (1 week after implantation), osteogenesis around implants was not disturbed. These results suggest that the new glass ceramic implant has good biocompatibility and is useful as an implant tooth.     

A comparison of growth and development of the dental arch, alveolar process, and palate in the lateral segment determined with reference to dental age and chronological age, particularly on the period of premolar eruption

The purpose of this study is to observe and compare growth and development in the dental arch, the alveolar process, and the palate in reference to dental age, which is based on tooth emergence, and chronological age. Subjects consisted of serial dental casts taken at two-month intervals from 40 children (20 males and 20 females) with normal occlusion in permanent dentition. In terms of dental age, observations were made for a total of two years, one year before and one year after the tooth emergence of first premolar and second premolar. In terms of chronological age, observations were made for a total of two years, one year before and one year after the average age of tooth emergence of first premolars and second premolars in this sample of children. Results and Conclusions. Comparisons between growth changes in the dental arch, the alveolar process, and the palate on dental and chronological age showed some regions in which growth patterns were similar and others in which growth patterns were different. The differences between both growth patterns from two ages were classified into two groups according to the tooth which caused the difference: those produced by the tooth used as a standard for dental age and those produced by teeth other than that used as a dental-age standard. 1) Differences resulting from the influence of the tooth used as a dental-age standard In regions of the tooth used as a dental-age standard, differences occurred in growth patterns on both kinds of age in practically all measured items. In regions adjacent to that of the tooth used as a dental-age standard, the differences were observed in growth patterns of the alveolar process and the palate but not in those of the dental arch. The differences were the most pronounced in the regions of dental-age-standard teeth than in the adjacent regions. The majority of the differences caused by teeth used as standards for dental age were thought to have been the results from the influence of eruption. No growth-pattern differences were observable in regions more than two teeth away from the tooth used as a dental-age standard. 2) Differences resulting from the influences of teeth other than that used as a dental-age standard Using the emergence time of a certain tooth as a dental-age standard, the emergence times of other teeth lead to be come together in some degree.(ABSTRACT TRUNCATED AT 400 WORDS)     

The effect of age on morphology and eruption of the lower incisors in mature rats

OBJECTIVE: This study investigated the effect of age on tooth and periodontium morphology and on tooth eruption in the lower incisors of 28 female rats, initial age 10 weeks. DESIGN: Morphometric data of the incisors in three young mature rats (weight 199+/-2.4 g) were compared to that of three 18-week-old (weight 260+/-5 g) animals. The rate of eruption was monitored during 12 months in 11 rats with all teeth in occlusion and in 11 rats with one lower incisor kept constantly out of occlusion. RESULTS:: The incisors continued to enlarge after the animals reached maturity with the size of the teeth increasing both longitudinally and circumferentially. Tooth volume increased by 21%, while that of the periodontal ligament was enlarged by only 12%. The rate of impeded eruption declined steadily from a mean value of 542+/-49 microm/day during the first experimental month to a mean value of 443+/-25 microm/day during the concluding month (p<0.05). The eruption rate of the teeth exceeded that of attrition rate by 2.4%. The unimpeded eruption proceeded steadily throughout the experimental year, at a mean rate of 811+/-12. CONCLUSIONS: Apparently in mature rats age has no effect on the genetic potential as expressed by the unimpeded eruption. In the impeded teeth age does affect the phenotypic expression of the eruptive function governed by occlusal forces as well as by the form and size ratio of the tooth and its PDL.     

Long-term results after intentional tooth reimplantation in monkeys.

The purpose of this study was to evaluate histologically the long-term response to intentional tooth reimplantation in six rhesus monkeys. The study revealed that cervical and apical root resorption is a universal complication after tooth reimplantation and that arrested areas of resorption will show repair by deposition of cementum. A highly cellular periodontal membrane usually will develop. Periodontal fibers will reattach to reparative bone and cementum but seldom regain functional orientation. Partial or complete ankylosis may result. A further complication is progressive undermining resorption of the ankylosed teeth. Long-term studies are mandatory to evaluate the response to intentional tooth reimplantation.     

Efficacy of bonded and nonbonded amalgam in the treatment of teeth with incomplete fractures

BACKGROUND: This clinical study compared the efficacy of adhesive-retained vs. pin-retained complex amalgam restorations in the treatment of molars with incomplete fractures. Both relief of chewing pain and cold sensitivity were evaluated at two weeks, three months and one year. METHODS: The authors treated 38 patients with a chief complaint of chewing sensitivity on vital molar teeth (40 teeth in the study). A random-number generator determined the treatment method for each tooth. Twenty teeth received bonded amalgam restorations. Twenty teeth received amalgapins or threaded pins to retain the amalgam. Teeth were evaluated for postoperative chewing sensitivity. A visual analog pain scale was used to evaluate cold response to a skin-refrigerant-soaked cotton pellet at each visit. After 12 months, all 40 teeth were available for evaluation. RESULTS: Chewing pain was completely eliminated in all but one tooth. A Student's t-test found no significant difference (P > .05) in preoperative cold sensitivity between the bonded and nonbonded groups. A paired t-test comparison indicated that the teeth in the bonded group were significantly less sensitive to cold after three months and 12 months than they were at the time of the baseline measurements (P < .0001). A paired t-test indicated no significant difference between preoperative and postoperative cold sensitivity scores for teeth in the nonbonded group (P > .05). CONCLUSIONS: Both adhesively bonded and mechanically retained complex amalgam restorations were successful in resolving chewing sensitivity in cracked molars. For 39 of 40 teeth, chewing sensitivity did not return during the one-year follow-up period. At three months and 12 months, cold sensitivity was reduced in the bonded restorations. At all three time periods, cold sensitivity remained similar to baseline levels for the mechanically retained restorations. CLINICAL IMPLICATIONS: Incomplete tooth fracture in molars can be successfully treated by covering fractured cusps with amalgam restorations. This study excluded teeth with prolonged sensitivity to a cold stimulus or those with periodontal evidence of root fracture. With these exclusions, elimination of chewing sensitivity was predictable. Teeth restored with bonded restorations experienced a decrease in sensitivity to a cold stimulus at three months and at 12 months, but not at two weeks. The cold sensitivity of teeth restored with nonbonded restorations was similar at baseline, two weeks, three months and one year.     

Immediate vs late orthodontic extrusion of traumatically intruded teeth

Abstract –  Although the published papers about this matter is limited to clinical case reports, the aim of this review was to quantify the success rate of immediate vs late orthodontic extrusion of traumatically intruded teeth. From 55 reports in a PubMed and Medline computerized search, 13 reported patients involving 22 traumatically intruded anterior upper teeth with orthodontic extrusion were selected. In the sample of 13 patients, six were males and seven females and the average age was 16.4 years old. The selection criteria were patients presenting traumatized anterior upper teeth resulting in intrusive luxation, with at least 1 year follow-up period. Orthodontic extrusive forces were applied in the immediate group within 10 weeks post-trauma, while in the late group the forces were applied only after 3 months post-trauma. Immediate and late orthodontic extrusion was extremely favorable. The success rate (without or with complications) was 95.4% against only 4.5% (1 tooth) because of inflammatory root resorption with rapid progression. All mature teeth (100%) were endodontically treated. Among the 12 immature traumatically intruded teeth, eight were endodontically treated and four were not. A high rate of success was reported in the literature in traumatically intruded teeth orthodontically extruded, either immediate or late.     

Periodontal healing after intentional auto-alloplastic reimplantation of injured immature upper front teeth

BACKGROUND/AIMS: Conventional endodontic treatment results in high complication quota when performed in immature teeth. Intentional reimplantation with extraoral insertion of an endodontic implant (auto-alloplastic reimplantation) is an alternative. METHOD: In a retrospective study, the healing of 40 teeth reimplanted intentionally according to this method in patients aged 7 to 15 years was evaluated. Clinical tests (palpation, percussion sound, periotest values) and radiographical examinations were used to determine the type of periodontal healing (inflammatory resorption/periodontitis apicalis; replacement resorption/ankylosis; normal healing). RESULTS: Mean lifetime of the replanted teeth was 59.2+/-42.5 months, estimated survival time on the basis of the Kaplan-Meier analysis was 99.5 months. 17 teeth (42.5%) were classified as failures, mostly due to inflammatory resorption or periodontitis apicalis. Further investigations demonstrated that success rate and retention period of intentionally replanted teeth depend on the preoperative condition of the pulp. Teeth with preoperative infection suffered frequently from inflammatory resorption or periodontitis apicalis after being replanted (14 of 28 teeth). Estimated survival time according to Kaplan-Meier was 75.5 months. In contrast, inflammations or progressive resorptions were not observed in teeth without preoperative infection of the pulp. All these 12 teeth showed normal periodontal healing and regular tooth mobility. In the absence of any pathology in clinical or radiological findings after an average functional period of 72.3 months, the prognosis can be presumed excellent. Estimated survival time of 148.3 months according to Kaplan-Meier differs significantly from survival time of teeth infected preoperatively. CONCLUSIONS: From the results of this investigation, it may be concluded that an infection of the pulp - due to delay of treatment or attempts at endodontic therapy - should be avoided before intentional replantation of immature front teeth with pulp necrosis. Periodontal healing of the autologous root is not impaired by the insertion of posts made of Al2O3-ceramics or titanium. The inserted posts do not ankylose. Orthodontic movement of auto-alloplastically replanted teeth is possible.     

Autotransplantation of premolars to premolar sites. A long-term follow-up study of 40 consecutive patients.

This article describes the long-term outcome of 40 consecutive patients having transplanted premolars. The objective of this ongoing study is to investigate survival rate, pulp survival rate, periodontal condition, and root development of autotransplanted premolars in orthodontic patients. This report covers 17 years; 32 orthodontic patients had 40 premolars transplanted into contralateral or opposing jaw quadrants where a premolar was missing. The teeth were examined systematically with clinical and radiographic measures at 1, 2, 6, 12, and 60 months or more after autotransplantation. The observation time varied from 2 years 5 months to 22 years 3 months, with a mean of 10 years 4 months. Bonded.018-in edgewise appliances were used, subjecting 87.5% of the transplanted teeth to normal orthodontic forces. One tooth was removed because of root fracture during the observation period, and 2 more had complications possibly related to the transplantation. The remaining 37 teeth and their supporting structures were all healthy at the last examination--a 92.5% success rate. Transplants with closed apices received endodontic therapy, but, in those with open or half-open apices, a 66% pulp survival rate was observed. No teeth in the sample had signs of replacement resorption or developed periodontal attachment loss. Inflammatory resorption in 2 teeth was arrested after endodontic treatment. Root formation, when not complete, continued on transplanted teeth, giving normal root form and adequate root length for normal function. It is concluded that autotransplantation of premolars combined with orthodontic treatment should be the first treatment alternative in cases of missing premolars, when a suitable donor tooth is available.     

大鼠牙周炎牙正畸移动后整合素β_3mRNA变化的实验研究

目的研究大鼠牙周炎牙及其正常牙在正畸移动中整合素β3mRNA的表达变化.方法选用10周龄雄性成年SD大鼠96只,随机分为正常牙组、牙周炎牙组,每组48只.分别在加力后0 d、12 h、1 d、3 d、5 d、7 d每一时间点处死8只动物,制备标本.采用原位杂交检测牙周炎牙与正常牙正畸移动后β3mRNA转录水平的变化.结果正常牙组和牙周炎牙组加力后12 h和3 d时的牙周膜内破骨细胞整合素β3mRNA阳性强度均较加力前有明显增加(P＜0.001);其余时间点未见整合素β3mRNA阳性表达.在加力各时间点,两组整合素β3mRNA的表达强度无显著性差异(P＞0.05).结论在正常牙及牙周炎牙移动早期,牙周膜和牙槽骨骨髓腔内有整合素β3mRNA表达,提示整合素β3可能参与破骨细胞前体向破骨细胞转化及破骨细胞迁移和粘附.     

Effect of human bone morphogenetic protein 2 implant on tooth eruption in an experimental design

This study evaluated the influence of recombinant human bone morphogenetic protein 2 (rhBMP-2) on the development and eruption of the secondary dentition. Primary premolar tooth extraction sockets in 12 16-week-old felines were implanted with either rhBMP-2, in collagen sponge or with buffer/absorbable collagen sponge (ACS). Unoperated jaw quadrants served as controls. Experimental conditions were randomized between jaw quadrants in all animals. Two animals receiving rhBMP-2/ACS and buffer/ACS in two quadrants per implant were sacrificed at 4 weeks postsurgery. Ten animals receiving rhBMP-2/ACS (two quadrants), buffer/ACS implants (one quadrant), and one quadrant serving as an unoperated control were evaluated at 12 weeks postsurgery. Clinical assessments included healing, eruption patterns, and crown development. Radiographic assessments included tooth development, eruption patterns, and bone formation. Histological observations were also made from the 4-week animals. The secondary dentition remained unerupted at 4 weeks postsurgery. Histological analysis showed normal alveolar bone coronal to the erupting teeth in rhBMP-2/ACS-implanted quadrants. At 12 weeks postsurgery, all teeth were erupted without differences between quadrants. Clinically, the crowns of all teeth were normal. Radiographs suggested that teeth in rhBMP-2/ACS- and buffer/ACS-implanted jaw quadrants exhibited similar tooth development and eruption patterns as the normal control. The evidence from this study suggests that surgical implantation of rh-BMP-2/ACS in the pathway of the developing and erupting secondary dentition does not interfere with the normal development and eruption patterns of the teeth.     

Pulp changes after anterior mandibular subapical osteotomy in a primate model.

Subapical osteotomy of the anterior mandible was carried out on 10 adult Macaca Irus monkeys with and without open bite. Teeth were extracted at 8 weeks, 12 weeks, 24 weeks and 1 year after surgery and the pulps examined histologically. No normal pulps were found. Progressive fibrosis and calcification was noted in all teeth. Patent pulp blood vessels were found up to 24 weeks after surgery. Pulp damage to teeth distal to the osteotomy site was found in 50% of cases. Control teeth extracted from the opposing jaw at the same intervals were all found to have normal pulps.     

The effect of orthodontic extrusion on traumatically intruded teeth

The management of traumatically intruded permanent incisors is controversial. Some authors suggest a decreased incidence of ankylosis in cases treated with orthodontic extrusion. The purpose of this study was to examine two common management techniques for traumatic intrusion, orthodontic extrusion, and observation for re-eruption. The four first premolars of three shepherd dogs were traumatically intruded with a mallet while a holding device was used to prevent tooth fracture. Five to 7 days following the injury, orthodontic force was applied unilaterally while the contralateral tooth served as the untreated control. To facilitate serial periapical radiography, x-ray jigs were fabricated for each animal and tantalum implants were placed in the bone distal to the permanent canine and first and second premolars. Observations included radiographic measurement of tooth movement, clinical estimates of tooth mobility, and radiographic and histologic assessment of root resorption, ankylosis, and periapical pathosis. The amount of traumatic intrusion varied from less than 0.5 to 4.1 mm. Following 11 to 13 weeks of force activation, 10 of 12 traumatized teeth showed clinical, radiographic, and histologic evidence of ankylosis irrespective of orthodontic treatment. Whereas the ankylosed teeth did not move with orthodontic forces, the teeth used for force application were orthodontically intruded 1.7 to 6.5 mm. When the injury to the tooth was severe, orthodontic extrusion had little effect on repositioning of the injured tooth but resulted in undesirable movement of the anchorage teeth. When the injury was less severe, orthodontic forces facilitated repositioning of the affected tooth.     

Use of a removable splint in the treatment of subluxated, luxated and root fractured anterior permanent teeth in children

Aim: The aim of this study was to evaluate the prognosis of subluxated, luxated and root fractured teeth in children treated by removable splints, designed to stabilize mobile anterior teeth and eliminate occlusal trauma due to malocclusion. Material and methods: A total of 227 traumatized anterior teeth (91 subluxated, 105 luxated and 31 root fractured teeth) treated with a removable splint were observed for 3 years. The traumatized teeth were from 79 children aged between 6–12 years (mean 8 years 5 months). If a traumatized tooth was extremely mobile, a fixed splint was first made before the impression was taken for the removable splint. Two weeks after completion of the removable splint treatment, an impression was taken again to evaluate the occlusal relationship of pre‐ versus post‐treatment of removable splint. Results: The treatment period with a removable splint averaged 3 weeks in subluxated teeth, 3–5 weeks in luxated teeth, 4–6 weeks in apical third root fracture injuries, and more than 5 weeks in middle third root fracture injuries. All the subluxated teeth and 74.1% of the luxated teeth maintained their pulp vitality during the 3‐year follow‐up period. Two of 21 (9.5%) apical third root fracture teeth and three of five (60%) middle third root fracture teeth had pulp necrosis in the coronal fragments. Internal resorption was not found in any of the traumatized teeth. External replacement resorption was not found in subluxated and luxated teeth. All the root fractured teeth displayed transient external resorption around the fracture lines. The surface resorption appeared to be self‐limiting and not to threaten the retention of the tooth. Inflammatory resorption was observed in teeth with pulp necrosis, but in all cases this was reversed with endodontic treatment. Eight of 23 (39%) apical third root fractured teeth displayed replacement resorption in their apical fragments, but the resorption was not serious enough to extract the tooth. No obvious alteration in the occlusal relationship was found comparing pre‐ and post‐treatment casts. The removable splints appeared to positively affect healing after traumatic injuries, as evidenced by the low number of complications at the 3‐year follow‐up period.     

Immediate reimplantation of primary teeth: a histological study in dogs

Abstract –  Reimplantation of primary teeth has been the subject of various clinical and histological studies, but very little is known about the effect of this treatment on primary teeth. The aim of the present study was to histologically evaluate the biological response of dog primary teeth after immediate reimplantation. Twelve dogs were divided into two groups according to postoperative time: 1 week and 3 weeks. Twenty-one upper and lower intermediate incisors were extracted and submitted to endodontic treatment, reimplantation and splinting. The 21 homologous teeth not submitted to treatment served as controls. The animals were killed after the respective experimental periods, and the obtained specimens were processed for histological analysis. Most dogs of the 1-week group exhibited the following alterations: gingival epithelium was inserted in the cemento-enamel junction, with a small number of chronic inflammatory cells being observed in the gingival corium; the periodontal ligament was partially reestablished, with a more expressive chronic inflammatory infiltrate being observed in the apical third; small root resorption was observed on the palatine/lingual side in the apical third. In contrast, in 3-week animals, gingival epithelial insertion was predominantly absent on the buccal side, and a moderate chronic inflammatory infiltrate was present; the periodontal ligament generally showed no bone-cementum reinsertion especially on the palatine/lingual side, with an expressive inflammatory infiltrate in the apical region, and large root resorption was mainly observed on the palatine and lingual sides. In conclusion, reimplantation causes histological alterations in the tooth and its supporting periodontal structures that suggest the impossibility of its maintenance.