Comparison of the Effects of Er, Cr: YSGG Laser and Super-Saturated Citric Acid on the Debridement of Contaminated Implant Surfaces.

Introduction: Several techniques such as using citric acid, plastic curettes, ultrasonic devices, and lasers have been suggested for debridement of contaminated implant surfaces. This comparative investigation aimed to assess and compare the effects of Er, Cr: YSGG laser and super-saturated citric acid on the debridement of contaminated dental implant surfaces. Methods: In this in-vitro study, 12 contaminated failed implants were collected and randomly divided into 2 groups (6 in group A, and 6 in group B). Also, one implant was considered as the control. The implants were horizontally sectioned into coronal and apical portions and subsequently irradiated by Er, Cr: YSGG laser in coronal and citric acid in apical in group A and the opposite in group B. In order to evaluate the effect of water spray on the laser section, half the laser portion of the implants was irradiated using water, while the other half was irradiated without water with an irradiation time of 1 minute. Results: Results revealed that calculus and plaque removal was greater in the laser part of both groups (with and without water) compared to citric acid parts and the correlation between calculus removal and surface roughness were statistically significant. Furthermore, the surface roughness in the citric acid parts was significantly higher than in laser parts. Water spray during irradiation had a very small influence on understudy factors. Conclusion: Based on the results of this study, the Er, Cr: YSGG laser was more effective in calculus removal and caused less surface roughness compared with citric acid application.

Biological Evaluation (In Vitro and In Vivo) of Bilayered Collagenous Coated (Nano Electrospun and Solid Wall) Chitosan Membrane for Periodontal Guided Bone Regeneration.

The application of barrier membranes in guided bone regeneration (GBR) has become a commonly used surgical technique in periodontal research. The objectives of this study were to evaluate the in vitro biocompatibility and osteogenic differentiation of mesenchymal stem cells (MSCs) on two different collagenous coatings (nano electrospun fibrous vs. solid wall) of bilayered collagen/chitosan membrane and their histological evaluation on bone regeneration in rabbit calvarial defects. It was found that chitosan-nano electrospun collagen (CNC) membranes had higher proliferation/metabolic activity compared to the chitosan-collagen (CC) and pristine chitosan membranes. The qRT-PCR analysis demonstrated the CNC membranes induced significant expression of osteogenic genes (Osteocalcin, RUNX2 and Col-α1) in MSCs. Moreover, higher calcium content and alkaline phosphatase activity of MSCs were observed compared to the other groups. Histologic and histomorphometric evaluations were performed on the uncovered (negative control) as well as covered calvarial defects of ten adult white rabbits with different membranes (CNC, CC, BioGide (BG, positive control)) at 1 and 2 months after surgery. More bone formation was detected in the defects covered with CNC and BG membranes than those covered by CC and the negative control. No inflammation and residual biomaterial particles were observed on the membrane surface or in the surrounding tissues in the surgical areas. These results suggest that bilayer CNC membrane can have the potential for use as a GBR membrane material facilitating bone formation.

Effects of counter torque and transposition (transfer) of installed implants timing on their integration in dog tibia.

PURPOSE: The purpose of this research was to evaluate the amount of reosseointegration after counter torquing (reverse torque) and transposing the installed implants at different times. MATERIALS AND METHODS: This study was done on ten tibiae of five cross-bred dogs. At the first day one implant was installed in each tibia. After one week half of the implants were randomly counter torqued (1WCT) and the other half were explanted and reimplanted in a new juxtaposition site (transposed)(1WT). At the same time three new implants were installed in each dog, one of them was considered as one week control (1WC) and remaining two as 8 week groups (8WCT&8WT). After eight weeks the 1WCT and 1WT implants were loosened by counter torque and the quantity of needed force for liberation was measured with the digital device (BGI). At the same time one implant was installed in each dog as eight week control (8WC) and the same protocol was repeated for 8 week groups after another 8 weeks. RESULTS: All implants were osseointegrated. Mean quantities of osseointegration in case groups indicated better amounts rather than control groups. CONCLUSION: Counter torque or transposition of the installed implants one week or eight weeks after the implantation did lead to osseointegration.

Three dimensional socket preservation: a technique for soft tissue augmentation along with socket grafting.

BACKGROUND: A cursory review of the current socket preservation literatures well depicts the necessity of further esthetic considerations through the corrective procedures of the alveolar ridge upon and post extraction. A new technique has been described here is a rotational pedicle combined epithelialized and connective tissue graft (RPC graft) adjunct with immediate guided tissue regeneration (GBR) procedure. RESULTS: We reviewed this technique through a case report and discuss it's benefit in compare to other socket preservation procedures. CONCLUSION: The main advantages of RPC graft would be summarized as follows: stable primary closure during bone remodeling, saving or crating sufficient vestibular depth, making adequate keratinized gingiva on the buccal surface, and being esthetically pleasant.

A clinical and histologic evaluation of gingival fibroblasts seeding on a chitosan-based scaffold and its effect on the width of keratinized gingiva in dogs.

BACKGROUND: Finding biocompatible matrix materials capable of enhancing the procedures of gingival augmentation is a major concern in periodontal research. This has prompted the investigation of a safe grafting technique by means of synthetic or natural polymers. The objective of this study is to examine the effect of a gingival fibroblast cultured on a naturally derived (i.e., chitosan-based) scaffold on the width of keratinized gingiva in dogs. METHODS: Gingival fibroblasts were cultured from a small portion of hard palates of five dogs. A bilayered chitosan scaffold was seeded with the gingival fibroblasts and transferred to dogs. Surgery was performed bilaterally, and the regions were randomly divided into two groups: chitosan only (control site) and chitosan + fibroblast (test site). Periodontal parameters, including probing depth and width of keratinized and attached gingiva, were measured at baseline and 3 months after surgery. A histologic evaluation was also performed on the healed grafted sites. RESULTS: Comparison of width of keratinized and attached gingiva in control and test sites showed that the mean width of keratinized and attached gingiva increased in each group after surgery. However, the difference between control and test groups was not statistically significant. Concerning the existence of the keratinized epithelium, exocytosis, and epithelium thickness, no significant difference was observed in test and control sites. The difference was significant in relation to rete ridge formation. CONCLUSION: The tissue-engineered graft consisting of chitosan + fibroblast was applied to gingival augmentation procedures and generated keratinized tissue without any complications usually associated with donor-site surgery.

Comparing alveolar bone regeneration using Bio-Oss and autogenous bone grafts in humans: a systematic review and meta-analysis.

INTRODUCTION: Bone regeneration grafts (BRG) are widely used in the treatment of osseous defects and oral surgery. The various techniques and associated success rates of bone augmentation require evaluation by systematic review and meta-analysis of eligible studies. The aim of this systematic review was to compare alveolar bone regeneration in humans using Bio-Oss and autogenous bone graft. MATERIALS AND METHODS: The computerized bibliographical databases including Pubmed, Google, ScienceDirect and Cochrane were searched for randomized and cohort studies in which autogenous grafts were compared to Bio-Oss in the treatment of periodontal defects. The inclusion criteria were human studies in English that were published 1998-2009. Exclusion criteria included non randomized observation and cohort studies, papers which provided summary statistics without the variance estimates, and studies that did not use BRG intervention alone, were excluded. The screening of eligible studies, assessment of the methodological quality of the trials and data extraction were collected by two observers independently. For comparing autogenous grafts used alone against Bio-Oss used alone 5 situations were investigated. Thirteen studies were included in the review which compared autogenous against Bio-Oss, autogenous combined with guided tissue regeneration (GTR) against GTR, Bio-Oss combined with GTR versus GTR, autogenous alone versus Open Flap Debridement (OFD), Bio-Oss versus OFD. In meta-analysis, changes in bone level (bone fill) was used as the measure. Data were analyzed using Bayesian meta-analysis by WinBUGS and Boa software. RESULTS: Only one comparison demonstrated that the difference in bone augmentation between Bio-Oss and OFD was statistically significant. CONCLUSION: There is insufficient evidence to show that Bio-Oss is superior to autogenous grafts in bone augmentation techniques however autogenous bone involves donor site surgery and thus donor site morbidity, so we can conclude that Bio-Oss is better than autogenous for alveolar regeneration. [Iranian Endodontic Journal 2009;4(4):125-30].

A comparative study of histologic response to different pulp capping materials and a novel endodontic cement.

OBJECTIVE: The aim of this study was to compare dogs' pulp response to capping with calcium hydroxide cement (Dycal), mineral trioxide aggregate (MTA), and a novel endodontic cement (NEC). STUDY DESIGN: Twenty-four canine teeth in 6 beagle dogs were buccocervically exposed and capped with MTA, Dycal, or NEC. Eight weeks later, retrieved samples were observed by optical microscope to grade inflammation, formation of dentinal bridge, calcification, necrosis, and presence of odontoblast cells. RESULTS: No inflammation was observed in MTA and NEC groups, and in 75% of each, dentinal bridge was completely formed. In the Dycal group, inflammation and incomplete dentinal bridge were detected in all cases. Although MTA and NEC groups had no significant difference between them in each measure, the difference between all 3 groups was significant (P < .001). CONCLUSION: MTA and NEC showed similar favorable biologic response in pulp cap treatment, better than Dycal, especially in inducing the formation of dentinal bridge.

The effects of loading time on osseointegration and new bone formation around dental implants: a histologic and histomorphometric study in dogs.

BACKGROUND: Immediate loading of dental implants has been introduced as a method of reducing implant treatment time without compromising its prognosis. In this research, the effects of loading time on the amount of bone-to-implant contact and bone formation around dental implants were evaluated histologically. METHODS: Three months prior to implantation, the lower premolar teeth of 15 dogs were extracted. Three or four dental implants were placed in the healed extraction sites for each dog (N = 48). Dividing the dogs into three groups, the implants were either loaded 48 hours or 1 week later with metallic or prefabricated acrylic crowns or were left unloaded until the time of sacrifice. Three months after implant insertion, the animals were sacrificed and samples were investigated to define the amount of bone-to-implant contact, lamellar and woven bone percentage, and local inflammation of the newly formed bone. RESULTS: No significant difference in the observed criteria was reported among the three groups (P >0.05); however, the unloaded group had the highest degree of bone-to-implant contact and the group loaded 48 hours after the primary implant insertion had the least. The prosthesis type had no significant effect on the implant success rate (P >0.05). The lamellar and woven bone percentage of newly formed bone also did not differ in the three groups (P >0.05). One implant from each group failed in this study. CONCLUSION: Loading time does not seem to significantly affect the degree of osseointegration and bone-to-implant contact and the composition of newly formed bone around dental implants.