Journal of Dental Medicine

Background and Aim: The goal of endodontics is to seal the root canal system from the orifice to apical constriction completely and tridimensionally.Hence perforations during root canal therapy, because of caries or resorptions must be sealed and obturated with ideal materials. The aim of this study was to histologically compare two kinds of mineral trioxide aggregate Root MTA and Pro Root MTA for furcal perforation repair in developed teeth in dog.

Materials and Methods: In this experimental study, thirty teeth consisting of second, third and fourth mandibular premolars of five German shepherd dogs were selected. Twenty-four teeth were randomly divided into four experimental groups (6 teeth each). One pair of Root MTA and Pro Root MTA groups studied in one month and the other in three months intervals. Positive and negative control groups was each contained three teeth. In positive control group, perforations were not treated and negative control group contained intact teeth. In experimental groups perforations repaired after one week exposure to oral cavity with Root MTA or Pro Root MTA. After time intervals animals were subjected to vital perfusion and 6 m histologic sections were prepared. Inflammation and hard tissue formation were ranked by Cox criteria. Data were analysed using Mann-Whitney and Chi-Square statistical tests with P<0.05 as the limit of significance.

Results: There was statistically significant lower inflammation and higher hard tissue formation in three months Root MTA and Pro Root MTA groups compared to one month interval (P<0.05). There was no statistically significant difference in inflammation and hard tissue formation between Root MTA and Pro Root MTA in each intervals (P>0.05).

Conclusion: Mineral Trioxide Aggregate is an adequate material for furcal perforation repair in dog’s teeth. Root MTA could be a good substitute for Pro Root MTA considering the lower cost and similar characteristics.

Background and Aim: One of the complications following major oral surgeries is mucosal defects and delayed healing process. Up to now, various mucocutaneous grafts have been used in this field and recently, amniotic membrane has been proposed as a biological dressing in dermatologic, ophthalmologic and otolaryngologic practices. The purpose of this pilot study was to evaluate the healing process following human amniotic membrane graft on oral keratinized mucosa of rabbit.

Materials and Methods: In this experimental animal study, two surgical mucosal defects with the same size were made in palatal mucosa of 10 rabbits with the same weight, gender and race and a graft of human amniotic membrane was used on one of the defects. On the 7th, 14th and 28th postoperative days, surgical biopsies were randomly obtained from grafted and ungrafted regions of 3, 4 and 3 rabbits, respectively and submitted for microscopic study.

Results: According to the results, grafted regions showed more surface epithelialization and thicker newly formed epithelium. Also inflammatory cells infiltration was less in these areas. In all cases, there was a remarkable cartilage formation in the connective tissue of the recipient sites.

Conclusion: The results of this study suggest that the use of amniotic membrane graft in oral surgery could be effective in healing process. Additional studies should be done using animal and human models with more samples. Furthermore, the formation of cartilage in the grafted sites and its possible potential in reconstruction of bone defects, needs to be studied.

Background and Aim: Replacing fractured ceramometal restorations may be the best treatment option, but it is costly. Many different bonding systems are currently available to repair the fractured ceramometal restorations. This study compared the shear bond strength of composite to a base metal alloy using 4 bonding systems.

Materials and Methods: In this experimental in vitro study, fifty discs, casted in a Ni-Cr-Be base metal alloy (Silvercast, Fulldent),were ground with 120, 400 and 600 grit sandpaper and divided equally into 5 groups receiving 5 treatments for veneering. Conventional feldspathic porcelain (Ceramco2, Dentsply Ceramco) was applied on control group (PFM or group1) and the remaining metal discs were air- abraded for 15 seconds with 50 mm aluminum oxide at 45 psi and washed for 5 seconds under tap water.Then the specimens were dried by compressed air and the  groups were treated with one of the bonding systems as follows: All-Bond 2 (AB), Ceramic Primer (CP), Metal Primer II (MP) and Panavia F2 (PF). An opaque composite (Foundation opaque) followed by a hybrid composite (Gradia Direct) was placed on the treated metal surface and light cured separately. Specimens were stored in distilled water at 37⁰C and thermocycled prior to shear strength testing. Fractured specimens were evaluated under a stereomicroscope. Statistical analysis was performed with one way ANOVA and Tukey HSD tests. P<0.05 was considered as the level of significance.

Results: Mean shear bond strengths of the groups in MPa were as follows: PFM group 38.6±2, All-Bond 2 17.06±2.85, Ceramic Primer 14.72±1.2, Metal Primer II 19.04±2.2 and Panavia F2 21.37±2.1. PFM group exhibited the highest mean shear bond strength and Ceramic Primer showed the lowest. Tukey's HSD test revealed the mean bond strength of the PFM group to be significantly higher than the other groups (P<0.001). The data for the PF group was significantly higher than AB and CP groups (P<0.05) and the shear bond strength of the MP group was higher than CP group, but was not significantly different from AB (P>0.05).

Conclusion: Based on the results of this study, the most reliable treatment for fractured metal-ceramic restorations would be the replacement of the restoration. If this is not possible, adhesive resin cements containing filler and phosphate-based monomers (especially MDP) such as Panavia F2 could be recommended for bonding composite to base metal alloys.

Background and Aim: The aim of this investigation was to evaluate the osteopromotion property of homogenous demineralized dentin matrix (HDDM) on experimental surgical bone defects in parietal bone of rabbits using the guided bone regeneration (G.B.R.) technique incorporating Paroguide collagen membrane.

Materials and Methods: Surgical bone defects were created in 6 Newzland white rabbits (2 defects in each rabbit). The defects were protected by Paroguide membrane alone (control group) or filled with HDDM and protected by Paroguide membrane (experimental group). The HDDM had been obtained from the central incisors of rabbits. The rabbits were sacrificed after 15, 30, 45, 60, 75 and 90 days and the defects examined histologically. Data were analyzed using pair-t test. The level of significance was set at p=0.03.

Results: Histologically, the volume of newly formed bone matrix was significantly greater in the experimental group. No inflammatory reaction was seen in either experimental or control groups.

Conclusion: Bone regeneration was accelerated in the bone defects filled with HDDM in comparison to the control group.