In vivo evaluation of resorbable supercritical CO2 -treated collagen membranes for class III furcation-guided tissue regeneration.

The study evaluated the effects of a Supercritical CO2 (scCO2 ) on a commercially available decellularized/delipidized naturally derived porcine pericardium collagen membrane, Vitala®. The Vitala® and scCO2 treated experimental membranes were evaluated for guided tissue regeneration (GTR) of periodontal tissue in class III furcation defects utilizing a dog model. Physical material characterization was performed by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The in vivo portion of the study was allocated to three-time points (6, 12, and 24-weeks) using standardized class III furcation defects created in the upper second and third premolars. The experimental defects (n = 5) were covered with either a collagen membrane (positive control), scCO2 -treated collagen membrane (experimental) or no membrane (negative control). Following sacrifice, histologic serial sections were performed from cervical to apical for morphologic/morphometric evaluation. Morphometric evaluation was carried out by ranking the presence of collagen membrane, amount of bone formation within the defect site and inflammatory cell infiltrate content. SEM showed the experimental scCO2 -treated membrane to have a similar gross fibrous appearance and chemical structure in comparison to the Vitala® Collagen membrane. A significant increase in membrane thickness was noted in the scCO2 -treated membranes (366 ± 54 µm) vs non-treated membranes (265 ± 75 µm). TGA and DSC spectra indicated no significant qualitative differences between the two membranes. For the in vivo results, both membranes indicated significantly greater amounts of newly formed bone (scCO2 : 2.85 ± 1.1; Vitala®: 2.80 ± 1.0) within the covered defects relative to uncovered controls (0.8 ± 0.27) at 24 weeks. Both membrane types gradually degraded as time elapsed in vivo from 6 to 12 weeks, and presented nearly complete resorption at 24 weeks. The inflammatory infiltrate at regions in proximity with the membranes was commensurate with healthy tissue levels from 6 weeks in vivo on, and periodontal ligament regeneration onset was detected at 12 weeks in vivo. The effect of the supplementary scCO2 treatment step on the collagen membrane was demonstrated to be biocompatible, allowing for the infiltration of cells and degradation over time. The treated membranes presented similar performance in GTR to non-treated samples in Class III furcation lesions. Defects treated without membranes failed to achieve regeneration of the native periodontium. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1320-1328, 2019.

Management of After-Hours Pediatric Dental Emergencies Among Pediatric and General Dentists.

Purpose: Assess how pediatric dentists (PD) and general practitioners (GP) manage after-hours pediatric dental emergencies according to perceived urgency. Methods: A survey was e-mailed to PD and GP in North Carolina. Participants responded to management of 18 cases (primary and permanent dentition) according to perceived urgency. Repeated-measures logistic regression was used to analyze factors influencing perception of clinical scenarios. Results: Response rates for PD and GP were 45.5% and 36.3%, respectively. Perceived urgency varied by clinical scenarios, dentition (primary vs. permanent), and practitioner (PD vs. GP) (P<.001). Practitioners with fewer years in practice or seeing fewer pediatric patients managed more cases as urgent. Traumatic injuries in primary dentition (intrusion, pulp exposure, palatal displacement, avulsion) were managed as more urgent by GP than PD (P<.001). Emergencies related to infection and permanent dentition were perceived similarly by PD and GP. Conclusions: Clinical scenarios highlighted disagreement in the management of after-hours pediatric dental emergencies between GP and PD, especially trauma in primary dentition. General practitioners tended to refer to an ED or see urgently, and PD tended to defer care. By identifying needs for improved education in dental trauma management, we can increase utilization of the dental home, avoiding use of overburdened EDs.

Regeneration of the cementum and periodontal ligament using local BDNF delivery in class II furcation defects.

Periodontal furcation defects are usually addressed by the placement of a physical barrier which may limit the regenerative potential of periodontal wounds. This study morphometrically quantified the regenerative effect of brain-derived neurotrophic factor (BDNF) in furcation defects in a non-human primate model. Grade II furcation defects (with and without induced inflammation prior to surgery) were created on the first and second molars of eight non-human primates. Defects were treated with open flap debridement and subsequently filled with either: Group A; BDNF (500 µg mL-1 ) in high-molecular weight-hyaluronic acid (HMW-HA), Group B; BDNF (50 µg mL-1 ) in HMW-HA, Group C; HMW-HA acid only, Group D; unfilled defect, or Group E; BDNF (500 µg mL-1 ) in saline. Periodontal wound healing was observed every 2 weeks by computed-tomography. At 11 weeks all animals were sacrificed and maxillary and mandibular block biopsies were referred for nondecalcified histology. Linear measurements of new cementum (cellular and acellular) and periodontal ligament (PDL) formation were performed. Computerized-tomography reconstruction and software quantification demonstrated successful bone fill for all groups. However, histometric assessment demonstrated significantly higher level of total periodontal regeneration for the 500 µg mL-1 BDNF HMW-HA relative to all other groups. No significant differences in cementogenesis were observed among groups. Significantly higher acellular cementum formation was observed for sites where inflammation was not induced prior to surgical procedures. While all groups experienced similar bone fill and cementogenesis, the 500 µg mL-1 BDNF HMW-HA appeared to most effectively repair PDL (minimum increase of ∼22% relative to all groups; over 200% relative to unfilled defects). © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1611-1617, 2018.

Validation of a new experimental model of extrusive luxation on maxillary molars of rats: a histological study.

BACKGROUND/AIM: The aim of this study was to test and validate a new model of extrusive luxation trauma on maxillary first molars of rats. MATERIAL AND METHODS: Forty adult male rats (Rattus norvegicus albinus, Wistar; weight = 230-250 g), 45 days old, were divided into eight groups (n = 5): control groups, in which animals were not subjected to any procedure and waited 1 day (GC1D) or 3 days (GC3D) for euthanasia, and experimental groups, in which animals were subjected to forces of 1100cN, 1300cN, or 1500cN and waited 1 or 3 days for euthanasia (GT1100/1D, GT1100/3D, GT1300/1D, GT1300/3D, GT1500/1D, GT1500/3D). In animals of the experimental groups, trauma was produced by an extrusive force in maxillary first right molars. Four-micrometer serial cuts stained with hematoxylin and eosin (HE) were made. Descriptive microscopic analysis of first upper right molar and semi-quantitative analysis (scores 1 to 4) of intensity of acute and chronic inflammation and vascular changes in the periodontal ligament and active and inactive external root resorption were conducted. The distribution of scores in the groups was compared using the Freeman-Halton extension of Fisher's exact test. The significance level was 5%. RESULTS: It was observed that vascular disorders (bleeding) on the periodontal ligament became more evident with increasing extrusive force. CONCLUSIONS: This new method was capable of generating histological changes, proving its secure application in this research area. The 1500cN force produced more damage on the periodontal ligament. CLINICAL RELEVANCE: The validation of a new experimental method can produce more reliable evidence in further research.

Mineral trioxide aggregate improves healing response of periodontal tissue to injury in mice.

BACKGROUND AND OBJECTIVE: Mineral trioxide aggregate (MTA) is a biomaterial used in endodontic procedures as it exerts beneficial effects on regenerative processes. In this study, we evaluate the effect of MTA on healing of periodontal ligament (PDL) and surrounding tissue, following injury, in a transgenic mouse model and on the differentiation of murine mesenchymal progenitor cells in vitro. MATERIAL AND METHODS: We used an inducible Cre-loxP in vivo fate mapping approach to examine the effects of MTA on the contributions of descendants of cells expressing the αSMA-CreERT2 transgene (SMA9+ ) to the PDL and alveolar bone after experimental injury to the root furcation on the maxillary first molars. Col2.3GFP was used as a marker to identify mature osteoblasts, cementoblasts and PDL fibroblasts. The effects of MTA were examined 2, 17 and 30 days after injury and compared histologically with sealing using an adhesive system. The effects of two dilutions of medium conditioned with MTA on proliferation and differentiation of mesenchymal progenitor cells derived from bone marrow (BMSC) and periodontal ligament (PDLC) in vitro were examined using the PrestoBlue viability assay, alkaline phosphatase and Von Kossa staining. The expression of markers of differentiation was assessed using real-time PCR. RESULTS: Histological analyses showed better repair in teeth restored with MTA, as shown by greater expansion of SMA9+ progenitor cells and Col2.3GFP+ osteoblasts compared with control teeth. We also observed a positive effect on differentiation of SMA9+ progenitors into osteoblasts and cementoblasts in the apical region distant from the site of injury. The in vitro data showed that MTA-conditioned medium reduced cell viability and osteogenic differentiation in both PDLC and BMSC, indicated by reduced von Kossa staining and lower expression of osteocalcin and bone sialoprotein. In addition, cultures grown in the presence of MTA had marked decreases in SMA9+ and Col2.3GFP+ areas as compared with osteogenic medium, confirming reduced osteogenesis. CONCLUSION: MTA promotes regeneration of injured PDL and alveolar bone, reflected as contribution of progenitors (SMA9+ cells) into osteoblasts (Col2.3GFP+ cells). In vitro, MTA-conditioned medium fails to promote osteogenic differentiation of both PDLC and BMSC.

Comparative evaluation of post-traumatic periodontal ligament cell viability using three storage media.

AIM: To evaluate the potential of milk, coconut water and buttermilk in maintaining periodontal ligament cell (PDL) viability. METHODS: Freshly extracted premolars (55) were divided into three experimental groups each having 15 teeth and the negative and positive control groups which had 5 teeth per group. The teeth in the experimental groups were immersed in their respective storage medium for a period of 75 min before the laboratory procedures were performed. Collagenase-dispase assays were conducted and the PDL cells were stained with 0.4% Trypan blue stain, which enabled cell counting to be performed under light microscopy at 45× magnification. RESULTS: These are presented as mean number of viable PDL cells/ml and % viable cells compared to the positive control (Group E). The statistically significant (p < 0.001) results showed that the milk group (Group A) had the maximum average number of viable PDL cells with 23,213.3 cells/ml (44.2%), followed by coconut water (Group B) which had 13,920 cells/ml (26.5%) and finally buttermilk (Group C) which had 10,566.6 cells/ml (20.1%) was the least effective. The results in this study were statistically significant (p < 0.001) when the Mann-Whitney test was used to compare distributions relative to their central tendency. CONCLUSION: Milk was found to be an excellent transport media for an avulsed tooth followed by coconut water and buttermilk.

Effect of Experimental Periodontal Ligament Pain on Gingival Somatosensory Sensitivity.

AIMS: To use a randomized, blinded, crossover design to evaluate the possible heterotopic effects of experimental periodontal ligament pain on adjacent gingival somatosensory sensitivity. METHODS: A total of 12 healthy volunteers (8 female, 4 male; mean age ± standard error in means (SEM): 28 ± 1 years) participated in two randomized experimental quantitative sensory testing (QST) sessions, one in which capsaicin (experimental) was injected into the periodontal ligament and one in which isotonic saline (control) was injected. A total of 13 standardized QST measures were obtained on the buccal attached gingiva of a maxillary central incisor before, immediately after, and 30 minutes after injection of 30 µL of 5% capsaicin or isotonic saline into the periodontal ligament of the same incisor. The injection-evoked pain was evaluated on a 0-10 numeric rating scale (NRS). QST data were analyzed with two-way repeated measurement analysis of variance. RESULTS: Capsaicin injected into the periodontal ligament evoked moderate levels of pain (mean peak NRS ± SEM: capsaicin: 5.5 ± .7; control: 0.6 ± 0.5 [P < .001]). Capsaicin injected into the periodontal ligament significantly modulated gingival somatosensory sensitivity: increased sensitivity to warmth and painful heat stimuli occurred immediately and 30 minutes after the injection (P < .025), whereas decreased sensitivity to both tactile and painful mechanical stimuli (P < .011) occurred immediately after the injection and to painful mechanical stimuli only after 30 minutes (P = .016). No somatosensory changes were detected following the injection of isotonic saline (P > .050). CONCLUSION: Capsaicin injected into the periodontal ligament caused gain of heterotopic somatosensory sensitivity toward warmth and painful heat stimuli as well as reduction in mechanical sensitivity of the gingiva adjacent to the injected tooth. These findings may have implications for interpretation of somatosensory functions in patients with chronic intraoral pain, where gingival somatosensory profiles similar to those detected after capsaicin injection in the present study may be interpreted as signs of nerve damage.

Tri-Layered Nanocomposite Hydrogel Scaffold for the Concurrent Regeneration of Cementum, Periodontal Ligament, and Alveolar Bone.

A tri-layered scaffolding approach is adopted for the complete and concurrent regeneration of hard tissues-cementum and alveolar bone-and soft tissue-the periodontal ligament (PDL)-at a periodontal defect site. The porous tri-layered nanocomposite hydrogel scaffold is composed of chitin-poly(lactic-co-glycolic acid) (PLGA)/nanobioactive glass ceramic (nBGC)/cementum protein 1 as the cementum layer, chitin-PLGA/fibroblast growth factor 2 as the PDL layer, and chitin-PLGA/nBGC/platelet-rich plasma derived growth factors as the alveolar bone layer. The tri-layered nanocomposite hydrogel scaffold is cytocompatible and favored cementogenic, fibrogenic, and osteogenic differentiation of human dental follicle stem cells. In vivo, tri-layered nanocomposite hydrogel scaffold with/without growth factors is implanted into rabbit maxillary periodontal defects and compared with the controls at 1 and 3 months postoperatively. The tri-layered nanocomposite hydrogel scaffold with growth factors demonstrates complete defect closure and healing with new cancellous-like tissue formation on microcomputed tomography analysis. Histological and immunohistochemical analyses further confirm the formation of new cementum, fibrous PDL, and alveolar bone with well-defined bony trabeculae in comparison to the other three groups. In conclusion, the tri-layered nanocomposite hydrogel scaffold with growth factors can serve as an alternative regenerative approach to achieve simultaneous and complete periodontal regeneration.

GDNF From Human Periodontal Ligament Cells Treated With Pro-Inflammatory Cytokines Promotes Neurocytic Differentiation of PC12 Cells.

Glial cell line-derived neurotrophic factor (GDNF) is known to mediate multiple biological activities such as promotion of cell motility and proliferation, and morphogenesis. However, little is known about its effects on periodontal ligament (PDL) cells. Recently, we reported that GDNF expression is increased in wounded rat PDL tissue and human PDL cells (HPDLCs) treated with pro-inflammatory cytokines. Here, we investigated the associated expression of GDNF and the pro-inflammatory cytokine interleukin-1 beta (IL-1ß) in wounded PDL tissue, and whether HPDLCs secrete GDNF which affects neurocytic differentiation. Rat PDL cells near the wounded area showed intense immunoreactions against an anti-GDNF antibody, where immunoreactivity was also increased against an anti-IL-1ß antibody. Compared with untreated cells, HPDLCs treated with IL-1ß or tumor necrosis factor-alpha showed an increase in the secretion of GDNF protein. Conditioned medium of IL-1ß-treated HPDLCs (IL-1ß-CM) increased neurite outgrowth of PC12 rat adrenal pheochromocytoma cells. The expression levels of two neural regeneration-associated genes, growth-associated protein-43 (Gap-43), and small proline-rich repeat protein 1A (Sprr1A), were also upregulated in IL-1ß-CM-treated PC12 cells. These stimulatory effects of IL-1ß-CM were significantly inhibited by a neutralizing antibody against GDNF. In addition, U0126, a MEK inhibitor, inhibited GDNF-induced neurite outgrowth of PC12 cells. These findings suggest that an increase of GDNF in wounded PDL tissue might play an important role in neural regeneration probably via the MEK/ERK signaling pathway. J. Cell. Biochem. 118: 699-708, 2017. © 2016 Wiley Periodicals, Inc.

The Role of a Platelet Lysate-Based Compartmentalized System as a Carrier of Cells and Platelet-Origin Cytokines for Periodontal Tissue Regeneration.

Currently available clinical therapies are not capable to regenerate tissues that are lost by periodontitis. Tissue engineering can be applied as a strategy to regenerate reliably the tissues and function of damaged periodontium. A prerequisite for this regeneration is the colonization of the defect with the adequate cell populations. In this study, we proposed a bilayered system composed of (1) a platelet lysate (PL)-based construct produced by crosslinking of PL proteins with genipin (gPL) for the delivery of rat periodontal ligament cells (rat-PDLCs); combined with (2) an injectable composite consisting of calcium phosphate cement incorporated with PL-loaded poly(d, l-lactic-co-glycolic acid) microspheres. This system was expected to promote periodontal regeneration by the delivery of adequate progenitor cells and providing a stable system enriched with adequate cytokines and growth factors for the orchestration of tissue regrowth in periodontal defects. The bilayered system was tested in a three-wall intrabony defect in rats and the healing of periodontal tissue was assessed 6 weeks after surgery. Results showed that the bilayered system was able to promote the regrowth of functional periodontal tissues, both with (cells + gPL) and without the loading of PDLCs (gPL). Significant connective tissue attachment (45.0 ± 15.0% and 64.0 ± 15.0% for gPL and cells + gPL group, respectively) and new bone area (33.8 ± 21% and 21.3 ± 3% for gPL and cells + gPL group, respectively) were observed. Nevertheless, rat PDLCs delivered with gPL construct in the defect area were hardly visible 6 weeks after surgery and did not contribute for the regeneration of new periodontal tissue. Overall, our findings show that the bilayered system promotes the stabilization of PL proteins on the root surface and has a positive effect in the repair of periodontal tissues both in quality and in quantity.

Prevention and management of external inflammatory resorption following trauma to teeth.

External inflammatory resorption is one of the potential consequences of trauma to the teeth. It occurs when there has been loss of cementum due to damage to the external surface of the tooth root during trauma, plus the root canal system has become infected with bacteria. It is characterized by the radiographic appearance of loss of tooth substance with a radiolucency in the adjacent periodontal ligament and bone. The loss of cementum allows the intracanal bacteria and/or their endotoxins to reach the periodontal ligament more readily and this can lead to the development of the inflammatory resorptive process. External inflammatory resorption can ultimately lead to loss of the tooth if it is not managed in a timely manner. There are some injuries that are very likely to develop this type of resorption and a preventive approach can be adopted by commencing root canal treatment immediately as part of the emergency management of such cases. In cases where the resorptive process is already established, root canal treatment can arrest the resorption and encourage hard tissue repair. The use of a corticosteroid-antibiotic intracanal medicament has been shown to be particularly useful in the prevention and management of external inflammatory resorption. Calcium hydroxide should not be used as an immediate medicament because of its inherent toxicity and irritant properties but it is valuable as a subsequent medicament to encourage hard tissue repair where required. This review outlines the external inflammatory resorptive process and the management strategies that can be employed to prevent it from occurring, and to treat it if already present.

Cementum and Periodontal Ligament Regeneration.

The unique anatomy and composition of the periodontium make periodontal tissue healing and regeneration a complex process. Periodontal regeneration aims to recapitulate the crucial stages of wound healing associated with periodontal development in order to restore lost tissues to their original form and function and for regeneration to occur, healing events must progress in an ordered and programmed sequence both temporally and spatially, replicating key developmental events. A number of procedures have been employed to promote true and predictable regeneration of the periodontium. Principally, the approaches are based on the use of graft materials to compensate for the bone loss incurred as a result of periodontal disease, use of barrier membranes for guided tissue regeneration and use of bioactive molecules. More recently, the concept of tissue engineering has been integrated into research and applications of regenerative dentistry, including periodontics, to aim to manage damaged and lost oral tissues, through reconstruction and regeneration of the periodontium and alleviate the shortcomings of more conventional therapeutic options. The essential components for generating effective cellular based therapeutic strategies include a population of multi-potential progenitor cells, presence of signalling molecules/inductive morphogenic signals and a conductive extracellular matrix scaffold or appropriate delivery system. Mesenchymal stem cells are considered suitable candidates for cell-based tissue engineering strategies owing to their extensive expansion rate and potential to differentiate into cells of multiple organs and systems. Mesenchymal stem cells derived from multiple tissue sources have been investigated in pre-clinical animal studies and clinical settings for the treatment and regeneration of the periodontium.

Cell-to-cell communication--periodontal regeneration.

BACKGROUND: Although regenerative treatment options are available, periodontal regeneration is still regarded as insufficient and unpredictable. AIM: This review article provides scientific background information on the animated 3D film Cell-to-Cell Communication - Periodontal Regeneration. RESULTS: Periodontal regeneration is understood as a recapitulation of embryonic mechanisms. Therefore, a thorough understanding of cellular and molecular mechanisms regulating normal tooth root development is imperative to improve existing and develop new periodontal regenerative therapies. However, compared to tooth crown and earlier stages of tooth development, much less is known about the development of the tooth root. The formation of root cementum is considered the critical element in periodontal regeneration. Therefore, much research in recent years has focused on the origin and differentiation of cementoblasts. Evidence is accumulating that the Hertwig's epithelial root sheath (HERS) has a pivotal role in root formation and cementogenesis. Traditionally, ectomesenchymal cells in the dental follicle were thought to differentiate into cementoblasts. According to an alternative theory, however, cementoblasts originate from the HERS. What happens when the periodontal attachment system is traumatically compromised? Minor mechanical insults to the periodontium may spontaneously heal, and the tissues can structurally and functionally be restored. But what happens to the periodontium in case of periodontitis, an infectious disease, after periodontal treatment? A non-regenerative treatment of periodontitis normally results in periodontal repair (i.e., the formation of a long junctional epithelium) rather than regeneration. Thus, a regenerative treatment is indicated to restore the original architecture and function of the periodontium. Guided tissue regeneration or enamel matrix proteins are such regenerative therapies, but further improvement is required. As remnants of HERS persist as epithelial cell rests of Malassez in the periodontal ligament, these epithelial cells are regarded as a stem cell niche that can give rise to new cementoblasts. Enamel matrix proteins and members of the transforming growth factor beta (TGF-ß) superfamily have been implicated in cementoblast differentiation. CONCLUSION: A better knowledge of cell-to-cell communication leading to cementoblast differentiation may be used to develop improved regenerative therapies to reconstitute periodontal tissues that were lost due to periodontitis.

The clinical meaning of external cervical resorption in maxillary canine: transoperative dental trauma

External Cervical Resorption in maxillary canines with pulp vitality is frequently associated with dental trauma resulting from surgical procedures carried out to prepare the teeth for further orthodontic traction. Preparation procedures might surgically manipulate the cementoenamel junction or cause luxation of teeth due to applying excessive force or movement tests beyond the tolerance limits of periodontal ligament and cervical tissue structures. Dentin exposure at the cementoenamel junction triggers External Cervical Resorption as a result of inflammation followed by antigen recognition of dentin proteins. External Cervical Resorption is painless, does not induce pulpitis and develops slowly. The lesion is generally associated with and covered by gingival soft tissues which disguise normal clinical aspects, thereby leading to late diagnosis when the process is near pulp threshold. Endodontic treatment is recommended only if surgical procedures are rendered necessary in the pulp space; otherwise, External Cervical Resorption should be treated by conservative means: protecting the dental pulp and restoring function and esthetics of teeth whose pulp will remain in normal conditions. Unfortunately, there is a lack of well-grounded research evincing how often External Cervical Resorption associated with canines subjected to orthodontic traction occurs.

A reabsorção cervical externa em caninos superiores com vitalidade pulpar em sua quase totalidade está associada a traumatismo dentário decorrente de procedimentos cirúrgicos associado à preparação desse dente para ser tracionado ortodonticamente. Nessa preparação pode se manipular cirurgicamente a junção amelocementária ou luxar o dente com forças excessivas ou com testes de movimentação além dos limites de tolerância estrutural do ligamento periodontal e tecidos cervicais. A exposição dentinária na junção amelocementária é o estopim para se iniciar uma reabsorção cervical externa a partir de uma inflamação induzida na região seguida de reconhecimento antigênico das proteínas dentinárias. A reabsorção cervical externa é indolor, não induz pulpites e tem uma evolução lenta. Em geral, a lesão está associada e recoberta por tecidos moles gengivais que mantêm, por longos períodos, os aspectos clínicos normais, induzindo diagnósticos tardios, quando o processo se aproxima dos limites pulpares. O tratamento endodôntico está indicado apenas em função de procedimentos operatórios que se fazem necessários no espaço pulpar; caso contrário, a reabsorção cervical externa deve ser tratada de forma conservadora, protegendo a polpa dentária e restaurando a função e estética do dente que permanecerá com sua polpa normal. Infelizmente, não sabemos, com base em pesquisas de casuísticas bem estabelecidas, qual é a frequência da reabsorção cervical externa associada a caninos ortodonticamente tracionados.

Management of traumatically intruded young permanent tooth with 40-month follow-up.

BACKGROUND: Intrusive luxation injuries often result in severe damage to the tooth, periodontal ligament and pulpal tissue. Furthermore, treatment outcome is often unpredictable because of the large number of injury related variables which influence choice of treatment and prognosis. This report presents the case of a 9-year-old boy with a 6 mm intruded permanent maxillary central incisor with an open apex. METHODS: The treatment option chosen was to wait and watch for 'spontaneous re-eruption'. At the end of two weeks, the tooth showed signs of pulp necrosis and external root resorption. A palatal mucoperiostal flap was reflected and endodontic access was established, following which an intracanal medicament of calcium hydroxide was applied. By the end of the fifth month, there was radiographic evidence of apical barrier formation and by the tenth month, the tooth had re-erupted to the level of the adjacent central incisor. Root canal treatment was completed at the end of 24 months and the root was reinforced using a glass fibre post. RESULTS: At the last follow-up visit (40 months after trauma), the tooth was asymptomatic and radiographic examination showed satisfactory periapical and periodontal healing. CONCLUSIONS: Spontaneous re-eruption is possible, even in severely intruded teeth with open apices.

Microscopic evaluation of induced tooth movement after subluxation trauma: an experimental study in rats.

OBJECTIVE: The objective of this study was to assess the histological alterations that occurred in the periodontal area of rat molars submitted to induced tooth movement (ITM) right after an intentional trauma (subluxation). METHODS: Forty adult male Wistar rats (Rattus norvegicus albinus) were selected. The animals were divided into eight groups (n=5), according to the combination of variables: Group 1--control (neither trauma nor ITM); Group 2--ITM; Groups 3, 4, 5 and 6--dentoalveolar trauma groups corresponding, respectively, to 1, 3, 8 and 10 days after trauma; Groups 7 and 8 - the animals' molars were subjected to a 900 cN impact and, one and three days after the trauma event, tooth movement was induced. The rats' maxillary first molars were mesially moved during seven days with a closed coil (50 cN). After the experimental period of each group, the animals were sacrificed by anesthetic overdose and the right maxillas were removed and processed for histological analysis under light microscopy. RESULTS: In the animals of group 3, 4, 5 and 6, the histological alterations were not very significant. Consequently, the effect of induced tooth movement right after a subluxation event (groups 7 and 8) was very similar to those described for Group 2. CONCLUSIONS: There was no difference in the quality of periodontal repair when ITM was applied to teeth that had suffered a subluxation trauma.

Experimental ex vivo traumatic intrusion in the mandibular incisors of the farm pig, Sus scrofa.

BACKGROUND/AIM: Traumatic intrusion of incisor teeth occurs frequently in young children, as well as in teens and adults; however, the biological mechanisms promoting negative sequelae or recovery are not well understood (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;107:493 and Vital Health Stat 11 2007;248:1). Modeling intrusive trauma and post-traumatic healing in an animal model offers the opportunity to define these biological mechanisms and to inform the design of treatments. The objective of this study was to investigate the pig, Sus scrofa, as a model for intrusive trauma, using an in vitro approach. MATERIALS AND METHODS: Mandibular segments from ex vivo farm pigs were bisected and primary central incisors were prepared to either receive axial traumatic loads or to serve as non-intruded controls. A class 2 lever modeled traumatic impact to the incisors. Damage to the periodontal support in intruded and control specimens (n = 10) was evaluated through compression testing and comparison of elastic moduli. Incisor displacement was measured on X-ray images taken before and after trauma, and following compressive tests. RESULTS: Lingual x-rays showed a mean postinjury displacement of the incisor root of 3.81 ± 1.87 mm. With compression testing, the root length embedded in bone increased in traumatized and non-traumatized teeth by 2.9 mm and 0.81 mm, respectively (P = 0.03). The intrusion group Young's modulus was significantly lower than the control group (4452 vs 7704 Mpa; P = 0.05). CONCLUSION: In vitro modeling of traumatic intrusion resulted in damage to the periodontal support of central incisors and axial tooth displacement. Pig incisors offer an important model for further study of incisor trauma.