Influence of the Connector and Implant Design on the Implant-Tooth-Connected Prostheses

Purpose:The purpose of this study was to evaluate stress transfer patterns between implant-tooth-connected prostheses comparing rigid and semirigid connectors and internal and external hexagon implants.Materials and Methods:Two models were made of photoelastic resin PL-2, with an internal hexagon implant of 4.00 x 13 mm and another with an external hexagon implant of 4.00 x 13 mm. Three denture designs were fabricated for each implant model, incorporating one type of connection in each one to connect implants and teeth: 1) welded rigid connection; 2) semirigid connection; and 3) rigid connection with occlusal screw. The models were placed in the polariscope, and 100-N axial forces were applied on fixed points on the occlusal surface of the dentures.Results:There was a trend toward less intensity in the stresses on the semirigid connection and solid rigid connection in the model with the external hexagon; among the three types of connections in the model with the internal hexagon implant, the semirigid connection was the most unfavorable one; in the tooth-implant association, it is preferable to use the external hexagon implant.Conclusions:The internal hexagon implant establishes a greater depth of hexagon retention and an increase in the level of denture stability in comparison with the implant with the external hexagon. However, this greater stability of the internal hexagon generated greater stresses in the abutment structures. Therefore, when this association is necessary, it is preferable to use the external hexagon implant.

Tooth replantation after use of euro-coffins solution or bovine milk as storage medium: a histomorphometric analysis in dogs

Purpose: Euro-Collins solution was developed for the preservation of organs for transplantation, whose characteristics have raised interest for its use as a storage medium for avulsed teeth before replantation. This study evaluated histologically and morphometrically the healing process of dog teeth replanted after storage in Euro-Collins solution or bovine milk.Materials and Methods: Eighty roots of 4 young adult mongrel clogs were randomly assigned to 4 groups (n = 20) and the root canals were instrumented and obturated with gutta-percha and a calcium hydroxide-based sealer. After 2 weeks, the teeth were extracted and subjected to the following protocols: GI (negative control), replantation immediately after extraction; GII (positive control), bench-drying for 2 hours before replantation; GIII and GIV, immersion in 10 mL of whole bovine milk and Euro-Collins solution at 4 C, respectively, for 8 hours before replantation. The animals were sacrificed 90 days postoperatively. The pieces containing the replanted teeth were subjected to routine processing for histologic and histometric analyses under light microscopy and polarized light microscopy.Results: Root resorption was observed in all groups. GII exhibited the greatest loss of dental structure (P < .01), and inflammatory resorption was predominant in this group. Storage in milk showed poorer results than immediate replantation and storage in Euro-Collins solution (P < .01). The teeth stored in Euro-Collins solution presented similar extension of root resorption and periodontal ligament reorganization to those of immediately replanted teeth.Conclusions: The findings of this study suggest that the Euro-Collins solution is an adequate storage medium for keeping avulsed teeth for up to 8 hours before replantation.

Calcium Hydroxide Mixed With Camphoric p-Monochlorophenol or Chlorhexidine in Delayed Tooth Replantation

This study evaluated the repair process after delayed replantation of rat teeth, using calcium hydroxide (Ca(OH)(2)) mixed with camphorated p-monochlorophenol (CMCP), chlorhexidine 2% (CHX), or saline as temporary root canal dressing to prevent and/or control inflammatory radicular resorption. Thirty Wistar rats (Rattus norvegicus albinos) had their right upper incisor extracted, which was bench-dried for 60 minutes. The dental papilla, the enamel organ, the dental pulp, and the periodontal ligament were removed. The teeth were immersed in 2% acidulated-phosphate sodium fluoride solution for 10 minutes. The root canals were dried with absorbent paper cones and divided into 3 groups of 10 animals according to root canal dressing used: group 1: Ca(OH)(2) + saline, group 2: Ca(OH)(2) + CMCP, and group 3: Ca(OH)(2) + CHX 2%. Before replanting, the teeth sockets were irrigated with saline. Histological analysis revealed the presence of inflammatory resorption, replacement resorption, and ankylosis in all 3 groups. Statistical analysis showed a significant difference between group 3 and the other groups. The use of Ca(OH)(2) mixed with CMCP or CHX did not show an advantage over the use of Ca(OH)(2) mixed with saline in preventing and/or controlling inflammatory resorption in delayed replantation of rat teeth.

Evaluation of tissue response to periodontal dressings: Histological study in tooth sockets of rats

Although the use of periodontal dressings is currently limited, there are some indications for their use. Selection of any material that will have direct contact with live tissues, such as periodontal dressings, should be careful in order to allow surgical wound healing. The aim of this study was to evaluate the intensity of inflammatory response and bone formation in tooth sockets of rats after implantation of three periodontal dressings. After removal of the right maxillary incisors of 84 male rats, each tooth socket received implantation of a polyethylene tube, 63 of which were filled with non-eugenol periodontal dressing and the remaining 21 tubes remained empty (control group). Histological evaluation assessed the intensity of inflammatory response and presence and location of bone tissue formation at postoperative periods of 7, 14 and 28 days. Statistical analysis was performed by the Kruskal-Wallis test at 5% significance level. Regarding the inflammatory infiltrate, at 28 days, there was statistically significant difference between one of periodontal dressings and control group (p < 0.05). Analysis of postoperative periods, showed that the control group presented statistically significant reduction in the inflammatory infiltrate comparing the 14- and 28-day periods (p < 0.05). Regarding bone tissue formation, there was difference in control group between the 7- and 28-day periods (p < 0.05). Within the experimental conditions, it may be concluded that no differences were found in the inflammatory response among the groups at 7 and 14 days and that Voco pac (TM) dressing induced a more intensive inflammatory reaction at 28 days.

Effect of low-level laser therapy on the healing process after tooth replantation: a histomorphometrical and immunohistochemical analysis

Success of tooth replantation is limited because part of the replanted tooth is lost because of progressive root resorption. This study used histomorphometry and immunohistochemistry to evaluate the effect of low-level laser therapy (LLLT) on the healing process of rat teeth replanted after different extra-oral periods, simulating immediate and delayed replantation. Sixty Wistar rats (Rattus norvegicus albinus) had their maxillary right incisors extracted and randomly assigned to six groups (n = 10): C4, C30 and C45, in which the teeth were replanted 4 min (immediate), 30 min (delayed) and 45 min (delayed) after extraction, respectively, and L4, L30 and L45, in which the teeth were replanted after the same extra-alveolar times, but the root surfaces and the alveolar wounds were irradiated with a gallium-aluminum-arsenate (GaAlAs) diode laser before replantation. The animals were sacrificed after 60 days. The anatomic pieces containing the replanted teeth were obtained and processed for either histomorphometrical analysis under optical microscopy or immunohistochemical expression of receptor activator of nuclear factor Kappa-B (RANK), and its ligand (RANKL), osteoprotegerin (OPG) and tartrate-resistant acid phosphatase (TRAP) proteins. Areas of external replacement and inflammatory root resorption were observed in all groups, without statistically significant differences (P > 0.05). Ankylosis was more frequent in L30 than in C30 (P < 0.05). RANKL immunostaining predominated over RANK and OPG immunostaining in both groups with immediate tooth replantation (P < 0.05). For the 45-min extra-alveolar time, however, there was greater evidence of RANK immunostaining compared to RANKL for both control and laser-treated groups (P < 0.05). Positive TRAP immunostaining predominated in L4 and L30 (P < 0.05). In conclusion, under the tested conditions, the treatment of the root surface and the alveolar wound with LLLT did not improve the healing process after immediate and delayed tooth replantation in rats.

Periapical tissue reactions to calcium hydroxide and MTA after external root resorption as a sequela of delayed tooth replantation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Treatment of root surface in delayed tooth replantation: a review of literature

The time elapsed between a trauma and tooth replantation usually ranges from 1 to 4 h. The chances of root surface damage are higher when tooth replantation is not performed immediately or if the avulsed tooth is not stored in an adequate medium. This invariably leads to necrosis of pulp tissue, periodontal ligament cells and cementum, thus increasing the possibility of root resorption, which is the main cause of loss of replanted teeth. This paper presents a comprehensive review of literature on root surface treatments performed in cases of delayed tooth replantation with necrotic cemental periodontal ligament. Journal articles retrieved from PubMed/MedLine, Bireme and Scielo databases were reviewed. It was observed that, when there are no periodontal ligament remnants and contamination is under control, replacement resorption and ankylosis are the best results and that, although these events will end up leading to tooth loss, this will happen slowly with no loss of the alveolar ridge height, which is important for future prosthesis planning.

Anterior Tooth Rehabilitation With Frozen Homogenous Bone Graft and Immediately Loaded Titanium Implant Using Computer-Guided Surgery

Computed tomographic scanning is a precise, noinvasive surveying technique that enables the professionals to improve the precision of implant placement by building a prototype that allows the confection of surgical guides. The authors present a clinical case of anterior tooth rehabilitation with frozen homogenous bone graft and immediately loaded titanium implant using computer-guided surgery. A multislice computed tomography was realized, and a prototype was built. All the procedures were previously realized in the prototype before started in the patient. This technique allows a better surgical planning, makes the procedures more accurate, and reduces surgery time.

Intracanal dressing and root canal filling materials in tooth replantation: a literature review

The prognosis of tooth replantation is usually related to the need of endodontic treatment, which has a direct relationship with the occurrence of root resorptions. Several studies have been undertaken in an attempt to prevent, delay, or treat these complications, which are the main causes of loss of replanted teeth. This literature review examines research evidence on intracanal dressings and root canal filling materials used in cases of tooth replantation. A comprehensive search was performed in the Medline/Pubmed, Bireme and Scielo full-text electronic journal databases to retrieve English-language articles referring to these topics that had been published between 1964 and 2010. Calcium hydroxide (CH) remains the usually recommended choice as an intracanal medicament in replanted teeth; however, there is evidence to support the initial use of a corticosteroid-antibiotic combination such as Ledermix paste to control potential early resorption, prior to the introduction of CH where the beneficial effect in the treatment of progressive root resorption has been well proven. Regarding root filling materials, CH-containing sealers are a good option because of their biological properties. Accurate diagnosis and adequate treatment plan may constitute very complex tasks, particularly in tooth avulsion because several variables are involved. In addition to the technical knowledge and clinical experience directed toward the quality of treatment, patient education may favorably influence the survival of replanted teeth.

Tooth replantation after keeping the avulsed tooth in oral environment: case report of a 3-year follow-up

Clinical practice has shown that most avulsed teeth are replanted after an extra-alveolar time that compromises the prognosis of replantation. In cases of delayed replantation, the use of adequate media for storage and transportation of the avulsed teeth may improve this prognosis considerably. Difficulties inherent to accidental dental avulsion include the lack of immediate access to ideal storage media, which accentuates the importance of saliva as a viable and readily available option. The authors report the case of an accidentally avulsed permanent maxillary central incisor that was kept into the patient's oral cavity from the moment of trauma until its replantation, 90 min later. Three years of follow-up revealed absence of root resorption, ankylosis or abnormal mobility, which demonstrates the feasibility of keeping avulsed teeth in saliva, at least when more indicated storage media are not available immediately.

Analysis of the healing process in delayed tooth replantation after root canal filling with calcium hydroxide, Sealapex and Endofill: a microscopic study in rats

The major concern in the therapeutics of tooth replantation refers to the occurrence of root resorption and different approaches have been proposed to prevent or treat these complications. The purpose of this study was to evaluate tissue response to delayed replantation of anterior rat teeth treated endodontically using calcium hydroxide, Sealapex, and Endofill without the placement of gutta-percha cones. Thirty rats had their right upper incisor extracted and maintained in dry storage for 60 min. After removal of the dental papilla, enamel organ, pulp tissue, and periodontal ligament remnants, the teeth were immersed in 2% sodium fluoride phosphate acidulated, pH 5.5, for 10 min. The root canals were dried with absorbent paper points and the teeth were assigned to three groups (n = 10) according to the filling material. Group I - calcium hydroxide and propyleneglycol paste, Group II - Sealapex, and Group III - Endofill. The sockets were irrigated with saline and the teeth were replanted. Replacement resorption, inflammatory resorption and ankylosis were observed in all groups. Although the occurrence of inflammatory resorption was less frequent in Group I, there were no statistically significant differences among the groups. It may be concluded that compared to the paste, filling the root canals with Sealapex and Endofill sealers without the placement of gutta-percha cones did not provide better results.

Effect of root surface treatment with propolis and fluoride in delayed tooth replantation in rats

Replantation is an acceptable option for treatment of an avulsed permanent tooth. Nevertheless, an extended extraoral period damages the periodontal ligament and results in external root resorption. The purpose of this study was to assess by histologic and histometric analysis, the influence of propolis 15% (natural resinous substance collected by Apis mellifera bees from various plants) and the fluoride solution used as root surface treatment on the healing process after delayed tooth replantation. Thirty Wistar (Rattus norvegicus albinus) rats were submitted to extraction of their upper right incisor. The teeth were maintained in a dry environment for 60 min. After this, the pulp was extirpated and the papilla, enamel organ and periodontal ligament were removed with scalpel. The teeth were divided into three experimental groups: Group I - teeth immersed in 20 ml of physiologic saline; Group II - teeth immersed in 20 ml of 2% acidulated phosphate sodium fluoride; Group III - teeth immersed in 20 ml of 15% propolis. After 10 min of immersion in the solutions, the root canals were dried and filled with calcium hydroxide paste and the teeth were replanted. The animals were euthanized 60 days after replantation. The results showed that similar external root resorption was seen in the propolis and fluoride groups. Teeth treated with physiologic saline tended to have more inflammatory root resorption compared with those treated with fluoride or propolis. However, the comparative analysis did not reveal statistically significant differences (P > 0.05) between the treatment modalities when used for delayed tooth replantation.

Influence of a Parafunctional Oral Habit on Root Fracture Development After Trauma to an Immature Tooth

Root fractures in immature teeth are rare because the resilience of the alveolar bone is more favorable to the occurrence of luxation. This article reports a case of traumatic injury in an immature permanent tooth that progressed to root fracture, having a parafunctional oral habit as the possible modifying factor of case evolution. A 12-year-old boy presented for treatment complaining of a defective restoration and mild pain on the maxillary right central incisor. The patient had a history of crown fracture in this tooth due to trauma 2 years before. The clinical examination showed healthy gingival tissues and no abnormal tooth mobility, whereas radiographic projections revealed healthy periradicular tissues, incomplete root formation, and no visible root fracture. As pulp necrosis was diagnosed, calcium hydroxide therapy was started for canal disinfection and subsequent obturation. However, after 4 weeks of treatment, a horizontal fracture line was observed radiographically in the root's middle third. The patient denied a new traumatic injury, but revealed the habit of chewing on a pencil. Refraining from the deleterious oral habit was strongly advised, and root canal filling with mineral trioxide aggregate was performed to treat the root fracture. After 4 years of follow-up, the tooth has normal function and no abnormal mobility. Images suggestive of remodeling at the apical end of the coronal segment and replacement resorption of the apical segment are seen radiographically. This case demonstrates the need of following cases of dental trauma and the possible influence of parafunctional oral habits as modifying factors of case progression.

Periodontal Tissue Engineering After Tooth Replantation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Occurrence of tooth injuries in patients treated in hospital environment in the region of Aracatuba, Brazil during a 6-year period

Dental trauma has been considered as a public health problem that affects mainly children and youngsters and due to its impact on the patient's quality of life. This study presents the results of a 6-year survey of the occurrence and characteristics of dental trauma in patients admitted to the Service of Surgery and Oral and Maxillofacial Traumatology of the School of Dentistry of Aracatuba (UNESP, Brazil) after emergency care in hospital facilities in the region of Aracatuba, SP, Brazil. For such purpose, the clinical files of patients treated at the Service between 1999 and 2005 were reviewed. Information regarding gender, age, number of traumatized teeth, etiology and diagnosis of the trauma was collected from the files of patients with tooth injuries and recorded in case report forms specifically designed for this purpose. The results showed that from a total of 4112 patients admitted to the Service within the surveyed period, 266 (6.5%) had tooth injuries (172 males - 64.7%; 94 females - 35.3%). The total number of traumatized teeth was 496. Most patients belonged to the 16-20 year-old age group (20.3%) and the most frequent causes of tooth injuries were bicycle accidents (28.6%), motorcycle accidents (19.2%) and falls (18.8%). Injuries to the periodontal tissues were the most frequent type of tooth injuries (408 teeth; 82.26%), occurring in 118 primary and 290 permanent teeth. Among the injuries to the periodontal tissues, avulsion was the most common (32.86%) (29.41% for primary and 34.0% for permanent teeth), followed by extrusive luxation (19.15%) (25.21% for primary and 17.24% for permanent teeth). In conclusion, in the surveyed population, cases of tooth injuries were more frequent in males aged 16-20 years old due to cyclist accidents with predominance of injuries to the periodontal tissues, in particular, avulsions.