Penetration of 35% hydrogen peroxide into the pulp chamber in bovine teeth after LED or Nd:YAG laser activation

This aim of the present study was to evaluate the pulp chamber penetration of 35% hydrogen peroxide activated by LED (light-emitting diode) or Nd:YAG laser in bovine teeth, after an in-office bleaching technique. Forty-eight bovine lateral incisors were divided into four groups, acetate buffer was placed into the pulp chamber and bleaching agent was applied as follows: for group A (n = 12), activation was performed by LED; for group B (n = 12), activation was performed by Nd:YAG laser (60 mJ, 20 Hz); group C (n = 12) received no light or laser activation; and the control group (n = 12) received no bleaching gel application or light or laser activation. The acetate buffer solution was transferred to a glass tube and Leuco Crystal Violet and horseradish peroxidase were added, producing a blue solution. The optical density of this solution was determined spectrophotometrically and converted into microgram equivalents of hydrogen peroxide. The results were analysed using ANOVA and Tukey's test (5%). It was verified that the effect of activation was significant, as groups activated by LED or laser presented greater hydrogen peroxide penetration into the pulp chamber (0.499 +/- 0.622 microg) compared with groups that were not (0.198 +/- 0.218 microg). There was no statistically significant difference in the penetration of hydrogen peroxide into the pulp chamber between the two types of activation (LED or laser). The results suggest that activation by laser or LED caused an increase in hydrogen peroxide penetration into the pulp chamber.

The importance of the lifelike esthetic appearance of all-ceramic restorations on anterior teeth

The success of rehabilitation will not depend on just clinical procedures. A proper dental technique (ceramist) is required as well as the respect for some biomimetic principles to obtain the desired final result. This study has the purpose of describing a prosthetic rehabilitation with laminate veneers and all-ceramic crowns of a patient unsatisfied with a previous esthetic treatment because of the negligence of some biomimetic principles. A 45-year-old female patient was admitted to the dental clinic complaining about the lifelike appearance of her all-ceramic restorations. Before the fabrication of new restorations, a mock-up was conducted to verify the patient's satisfaction. A ceramist conducted all the fabrication process so that surface characterizations could be visually verified and the lifelike appearance of natural tooth could be reproduced. After the cementation procedure, the patient reported being satisfied with the lifelike appearance of the new restorations. Based on the clinical findings of the present case report, it can be concluded that the reproduction of the lifelike esthetic appearance of natural teeth and the visualization of the final results before definitive procedures are essential to obtain the clinical success.

Demineralization and hydrogen peroxide penetration in teeth with incipient lesions

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

Longitudinal evaluation of the structural integrity of teeth affected by molar incisor hypomineralisation

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

Delayed tooth replantation following root canal filling with calcium hydroxide and MTA: Histomorphometric study in rats

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

Fracture resistance of weakened bovine teeth after long-term use of calcium hydroxide

In some parts of the world, revascularization may not be the most feasible treatment option for necrotic immature teeth. Therefore, apexification remains the most widely utilized treatment option for these cases. This study aimed to evaluate the fracture resistance of weakened bovine tooth roots treated with various irrigant solutions as well as long-term application of calcium hydroxide intracanal medication (ICM). One hundred seventy bovine teeth were randomly divided into three experimental groups (n = 50) and two control groups (n = 10). Group SS was irrigated with physiologic solution; group CHX was treated with 2% chlorhexidine gel and group NaOCl was irrigated with 1% sodium hypochlorite. After instrumentation, root canals were dressed with calcium hydroxide and evaluated at different periods (15, 60, 90, 180, and 360 days). The specimens were loaded at a 45° angle to measure fracture resistance through the use of an EMIC test machine. A decrease in fracture resistance was observed during the time of ICM dressing. The highest values of fracture resistance were observed in group SS with 15 days of ICM, not differing from the control group. Irrigation with NaOCl associated with ICM for 15 days presented the lowest fracture resistance; however, a statistically significant difference was not observed when compared with SS and CHX in the same time period. In longer periods of exposure to ICM (180 and 360 days), root canals irrigated with NaOCl and CHX showed significantly lower fracture resistance than SS (P < 0.05). Apexification with periodic changes of calcium hydroxide medicament leads to weakness of the teeth independent of the irrigation solution used.

Sequential healing at implants with different configuration and modified surfaces: an experimental study in the dog

To evaluate the peri-implant soft and hard tissue adaptation at implants with different modified surfaces and configurations. Six Beagle dogs were used. Mandibular premolars and first molars were extracted bilaterally. After 3 months, full-thickness flaps were elevated, and two different types of trans-mucosal implants (ICX-Gold®, Medentis Medical GmbH, Dernau, Germany and SLActive®, Institute Straumann, Bern, Switzerland) and two different surfaces were randomly installed in the distal regions of one side of the mandible. Abutments were applied, and a nonsubmerged healing was allowed. After 1 month, the procedures were performed in the other side of the mandible, and after a further month, the animals were sacrificed, biopsies were collected, and ground sections prepared for histological examination. Similar results in marginal bone and soft tissues dimensions were observed after 1 month of healing at the two implant systems used, and no major changes could be observed after 2 months of healing. After 1 month, the percentage of new bone was 69.0% and 68.8% at ICX-Gold and SLActive surfaces, respectively. After 2 months, the percentage of new bone was 67.8% and 71.9% at ICX-Gold Medentis and SLActive surfaces, respectively. No statistically significant differences in osseointegration were found. The two implant systems used resulted in similar osseointegration after 1 and 2 months of healing.

Immediate tooth replantation in rats: effect of systemic antibiotic therapy with amoxicillin and tetracycline

The aim of this study was to evaluate the influence of systemic administration of antibiotics (amoxicillin and tetracycline) at the different phases of the repair process (7, 15, 30 days) in immediate rat tooth replantation. Ninety rats had their incisors extracted and stored in saline for 5 min. Next, the teeth were replanted, and the animals were assigned to three groups according to the antibiotic administered by oral gavage: control group, amoxycillin group, and tetracycline group. Euthanasia was performed at 7, 15, and 30 days after replantation. Regardless of the evaluation period, the connective tissue underlying the epithelial attachment and the periodontal ligament showed statistically significant difference relative to the acute inflammatory infiltrate, which was more intense in the control group followed by the tetracycline group. These results point to the fact that systemic antibiotic therapy (SAT) in immediate tooth replantation is beneficial to pulpal and periodontal ligament repair and that amoxycillin is an excellent option. There is a lack of randomized studies assessing how the use of systemic antibiotics could influence tooth healing after immediate replantation.

Proximal caries lesion detection in primary teeth: does this justify the association of diagnostic methods?

The aim of this clinical study was to evaluate and compare the performance of visual exam with use of the Nyvad criteria (visual examination - (VE)), interproximal radiography (BW), laser fluorescence device (DIAGNOdent Pen-DDPen), and their association in the diagnosis of proximal lesions in primary teeth. For this purpose, 45 children (n = 59 surfaces) of both sexes, aged between 5 and 9 years were selected, who presented healthy primary molars or primary molars with signs suggestive of the presence of caries lesions. The surfaces were clinically evaluated and coded according to the Nyvad criteria and immediately afterwards with the DDPen. Radiographic exam was performed only on the surfaces coded with Nyvad scores 2, 3, 5, or 6. Active caries lesions and/or those with discontinuous surfaces were restored, considering the depth of lesion as reference standard. Sensitivity, specificity, accuracy, and area under ROC curve were calculated for each technique and its associations. Visual exam with Nyvad criteria presented the highest specificity, accuracy, and area under ROC curve values. The DDPen presented the highest sensitivity values. Association with one or more methods resulted in an increase in specificity. The performance of visual, radiographic, and DDpen exams and their associations were good; however, the clinical examination with the Nyvad criteria was sufficient for the diagnosis of interproximal lesions in primary teeth.

Delayed tooth replantation in rats: effect of systemic antibiotic therapy with amoxicillin and tetracycline

Systemic antibiotic therapy (SAT) has usually been recommended after tooth replantation, but its actual value has been questioned. As there are no reports in the literature about its influence on tooth replantation, the aim of this study was to evaluate the influence of systemic administration of antibiotics (amoxicillin and tetracycline) at the different phases of the repair process (7, 15, 30 days) in delayed rat tooth replantation. Ninety Wistar rats (Rattus norvegicus albinus) had their maxillary right incisors extracted and bench-dried for 60 min. The dental papilla, enamel organ, pulp tissue, and root surface-adhered periodontal ligament were removed, and the teeth were replanted. The animals received no antibiotics (n = 30) or were medicated systemically with amoxicillin (n = 30) and tetracycline (n = 30), and were euthanized after 7, 15, and 30 days. Regardless of the evaluation period, the acute inflammatory infiltrate was less intense and root resorption presented smaller extent and depth in the group treated with amoxicillin. The results suggest that SAT has a positive influence on the repair process in delayed tooth replantation and that amoxicillin is an excellent treatment option.

Drifting of teeth in the mandible studied in adult human autopsy material

Increase in lower anterior crowding is a general problem among adult Caucasians. The tooth movement responsible for this phenomenon, however, is not fully elucidated. Aim of this study was to describe signs of ongoing tooth movement reflected in the thickness of the bundle bone around mandibular teeth and the distribution of eroding surfaces of the alveolar wall in human autopsy material. The distribution of bundle bone and eroding surfaces was assessed histomorphometrically on 106 mandibular teeth, and the surrounding bone obtained at autopsy from 35 deceased persons ranging from 19 to 55 years of age. By examining the mesio-distal and bucco-lingual aspects at the cervical and apical levels of the roots, a pattern of tooth movements could be established. The distribution of the bundle bone thickness and the vectors of eroding surfaces enabled the direction of tooth movement to be reconstructed. Mesial and lingual displacement was prevalent for the anterior teeth. The signs of ongoing displacement of lower teeth support the concept of crowding occurring in adult individuals and support the maintenance of retainers, even following cessation of growth.

Bond strength of artificial teeth attached to a microwave-polymerized denture base resin after immersion in disinfectant solutions

To evaluate the bond strength between two types of acrylic resin teeth and a microwave denture base resin after immersion in disinfectant solutions for 180 days. Eighty specimens made of acrylic resin teeth (Biotone and Biotone IPN) attached to a microwave polymerized denture base resin (Nature-Cryl MC) were divided into eight groups (n = 10) according to the treatment (distilled water-control, 2% chlorhexidine digluconate, 1% sodium hypochlorite and sodium perborate solution-Corega Tabs). The shear strength tests (MPa) were carried out using a universal testing machine with a 0.5 mm/min speed. Data analysis was performed using ANOVA and multiple comparison Student-Newman-Keuls post hoc test (α = 0.05). Biotone IPN showed similar results among the groups (distilled water, 8.25 ± 1.81 MPa; chlorhexidine, 7.81 ± 3.34 MPa; hypochlorite, 7.75 ± 3.72 MPa; and Corega Tabs, 7.58 ± 2.27 MPa, whereas Biotone showed significantly lower shear bond strength values for the groups immersed in Corega Tabs (5.25 ± 3.27 MPa) and chlorhexidine (6.08 ± 2.35 MPa). Soaking the dentures in 1% sodium hypochlorite could be recommended as a disinfectant solution for dentures fabricated with conventional acrylic resin denture teeth and microwave denture base resin. For dentures fabricated with IPN teeth and microwave denture base resin, all the soaking solutions evaluated in this study could be suggested to denture wearers.

Determination of the p-monochlorophenol residue in the calcium hydroxide plus p-monochlorophenol combination used as an intracanal dressing in pulpless teeth of dogs with induced chronic periapical lesion

To determine the presence of p-monochlorophenol in the calcium hydroxide (Calen) + p-monochlorophenol combination after its use as intracanal dressing, periapical lesions were induced in 60 root canals of upper and lower premolars of four dogs, After biomechanical preparation, the root canals received the intracanal medication, which was removed from the apical third after 2, 4, 7, and 14 days for chemical analysis by spectrophotometry, the results showed a p-monochlorophenol loss of approximately 50.0% in the dressing after 48 h, with no further significant loss after longer periods of times, p-Monochlorophenol was still present in the medication after 14 days.

Epidemiological aspects of dog bites considering biter dogs and victims

The aim of this study was to characterize dog bites using data on biter dogs and victims. An exploratory cross-sectional study was performed using 203 records of individuals who had attended in public health services in 2009 in the municipality of Araçatuba, São Paulo, Brazil, after they had been bitten by a dog. Over 70% (92/129) of the biter dogs were male and most of them (71%) received as a gift. Dog owners reported companionship as the main reason for acquiring the dog. The victims who were children were predominantly male, while the victims who were elderly were predominantly female. Most children were bitten on the head/neck, while adults were bitten on the hands/feet and lower limbs (p<0.0001). The owner of the dog was known in 83.2% of cases. However, rabies observation of the biter dog following the attack was only reported in 59.4% of cases. Situations involving aggression were related to dogs having escaped from their home (18.7%) or roaming free on the streets (17.0%). The analysis of biting dog characteristics using information obtained from dog bite victims and biting dog owners can help direct the medical treatment for dog bite victims. Moreover, concepts of responsible dog ownership can reduce the occurrence of bites.

Delayed tooth replantation after treatment of necrotic periodontal ligament with citric acid

Objective: to evaluated the effect of treating root-adhered necrotic periodontal ligament (PDL) with citric acid on the healing process in delayed rat tooth replantation. Material and Methods: Forty Wistar rats, assigned to 4 groups (n=10), had their upper right incisor extracted and kept dry on a workbench. For Group I (control), the teeth were replanted after a 5 min extra-alveolar time. For the other groups, replantation was hydroxide-based paste and the teeth were replanted with no root surface treatment. In Group III, the teeth were immersed in citric acid (pH 1) for replanted. In Group IV, instead of the immersion, the roots were scrubbed with gauze soaked in citric acid and the teeth were replanted. The animals difference (p > 0.05) was found among the groups regarding the areas difference (p < 0.05) between the control group and Group IV regarding ankylosis. The control group showed the least replacement resorption percent means compared to the other groups (p < 0.05). The root structure was more affected by replacement resorption and ankylosis in Group IV statistically (p > 0.05). Conclusion: the treatment of root surface-adhered necrotic periodontal ligament with citric acid was not able to prevent the delayed rat tooth replantation.