Present status and future directions:Apexification

The success rate of apexification is primarily determined by multiple factors,including the material used,the size of the open apex compared to the length of the root,and the technique used in each case.The main objective of this review was to provide an update on the present management of open apex to identify factors and circumstances that may influence the success of apexification using different materials and techniques.Future research on apexification should focus on how to treat open apices with wide periapical lesions without surgery.Previously,the predictability of these parameters with non-surgical procedures was uncertain,but now,with the use of a dental operating microscope,it has become more predictable.Another reason could be that extra visits are no longer required due to major advances in the armamentarium and materials used for apexification.

Long-term observation of the mineral trioxide aggregate extrusion into the periapical lesion:a case series

One-step apexification using mineral trioxide aggregate(MTA) has been reported as an alternative treatment modality with more benefits than the use of long-term calcium hydroxide for teeth with open apex.However,orthograde placement of MTA is a challenging procedure in terms of length control.This case series describes the sequence of events following apical extrusion of MTA into the periapical area during a one-step apexification procedure for maxillary central incisor with an infected immature apex.Detailed long-term observation revealed complete resolution of the periapical radiolucent lesion around the extruded MTA.These cases revealed that direct contact with MTA had no negative effects on healing of the periapical tissues.However,intentional MTA overfilling into the periapical lesion is not to be recommended.

Effect of acid etching on marginal adaptation of mineral trioxide aggregate to apical dentin:microcomputed tomography and scanning electron microscopy analysis

The present investigation assessed the effect of acid etching on marginal adaptation of white- and gray-colored mineral trioxide aggregate （MTA） to apical dentin using microcomputed tomography （micro-CT） and scanning electron microscopy （SEM）. Sixty-four extracted single-rooted human maxillary teeth were used. Following root-end resection and apical preparation, the teeth were equally divided into four groups according to the following root end filling materials： （i） white-colored MTA （WMTA）, （ii） etched WMTA （EWMTA）, （iii） gray-colored MTA （GMTA） and （iv） etched GMTA （EGMTA）. After 48 h, the interface between root-end filling materials and the dentinal walls was assessed using micro-CT and SEM. Data were statistically analyzed using the KruskaI-Wallis and Dunn tests. Micro-CT analysis revealed gap volumes between the apical cavity dentin walls and EGMTA, GMTA, EWMTA and WMTA of （0.007 1±0.004） mm3, （0.053±0.002） mm3, （0.003 6±0.001） mm3 and （0.005 9±0.002） mm3 respectively. SEM analysis revealed gap sizes for EGMTA, WMTA, EWMTA and GMTA to be （492.3±13.8） μm, （594.5±17.12）μm, （543.1±15.33） μm and （910.7±26.2）μm respectively. A significant difference in gap size between root end preparations filled with GMTA and EGMTA was found （P〈O.05）. No significance difference in gap size between WMTA and EWMTA were found in either SEM or micro-CT analysis. In conclusion, pre-etching of apical dentin can provide a better seal for GMTA but not for WMTA.

Long-term follow-ups of revascularized immature necrotic teeth:three case reports

Revascularization of immature necrotic teeth is a reliable treatment alternative to conventional apexogenesis or apexification. In case 1, a 12-year-old boy had his necrotic, immature mandibular left second premolar treated with a revascularization technique. At a 24-month follow-up, periapical radiolucency had disappeared and thickening of the root wall was observed. In cases 2 and 3, a lO-year-old boy had his necrotic, immature, bilateral mandibular second premolars treated with the same modality. At 48-month （in case 2） and 42-month （in case 3） follow-ups, loss of periapical radiolucencies and increases in the root wall thickness were also observed.

An evaluation of the inflammatory response of lipopolysaccharide-treated primary dental pulp cells with regard to calcium silicate-based cements

This study compared the biological changes of lipopolysaccharide （LPS）-treated dental pulp （DP） cells directly cultured on mineral trioxide aggregate （MTA） and calcium silicate （CS） cements. DP cells were treated with LPS for 24 h. Then, the LPS-treated DP cells were cultured on MTA or CS cements. Cell viability, cell death mechanism and interleukin （IL）-1β expressions were analysed. A one-way analysis of variance was used to evaluate the significance of the differences between the means. A significantly higher IL-1β expression （2.9-fold） was found for LPS-treated cells （P〈0.05） compared with DP cells without LPS treatment at 24 h. Absorbance values of LPS-treated cells cultured on CS cement were higher than a tissue culture plate. A significant difference （P〈0.05） in cell viability was observed between cells on CS and MTA cements 24 h after seeding. At 48 h, a high concentration of Si （5 mM） was released from MTA, which induced LPS-treated DP cell apoptosis. The present study demonstrates that CS cement is biocompatible with cultured LPS-treated DP cells. MTA stimulates inflammation in LPS-treated DP cells, which leads to greater IL-1β expression and apoptosis.

The inflammatory response of the pulp after direct capping with platelet-rich plasma and enamel matrix derivative:A controlled animal study

Aims: To evaluate the inflammatory response of the exposed pulp of incisor teeth in rats after direct pulp capping, using platelet rich plasma (PRP), enamel matrix derivate (EMD), mineral trioxide aggregate (MTA) and calcium hydroxide (Ca(OH)2). Methods: The study was conducted on 36 Wistar albino rats with a total of 144 incisor teeth. The pulps of 96 teeth of the rats were perforated and capped with different agents. Serving as the positive control group, the pulps of 24 teeth were only perforated and capped without capping agents, whereas the pulps of 24 teeth were used as the negative control group without being perforated (without any process). The research was ended with the extracting of the teeth on the 7th day-28th day. The teeth were taken to the routine and histological follows;cross sections were prepared and painted with hematoxylen & eosin. All of the sections were evaluated in terms of inflammatory reaction by histologic analysis taken by light microscope. Statistical analysis was used. The normal distribution of all data was tested with the Mann Whitney U and the differences between the groups were analyze dusing Kruskal Wallis test at 0.05 level. Results: There are no statistically significant differences in terms of inflammation type and necrosis among the treatment groups on 7 days’ post capping. However, improved inflammatory cell accumulation, hyperemia and lowest necrosis were observed from the samples treated with PRP (p < 0.05). Conversely, the EMD group indicated that the criteria of inflammation scores and hyper- emia were higher in the 28th day (p < 0.05). Conclusions: Most of cells accumulating in the PRP group and most necrosis were seen in the EMD group. These new PRP materials might serve as pulp capping biomaterials to induce initial healing response in the future.

Calcium Silicate Cements Application in Lateral Root Perforation Repair: A Case Report with 16-Month Follow-Up

Lateral root perforations are unfortunate procedures during endodontic treatment and often lead to tooth extraction. Conditioning factors such as time, size, location, inappropriate disinfection and sealing, are indispensable to achieve acceptable long-term outcomes. Calcium silicate cements are bioactive materials used for perforation repair. They can be set in moist environments such as blood, saliva and dentinal fluid making them a reliable material for clinical applications. This case report describes the treatment and repair after a 16-month follow-up of a lateral root perforation of the maxillary lateral incisor.

Evaluation of the properties of Mineral Trioxide Aggregate mixed with Zinc Oxide exposed to different environmental conditions

Addition of zinc oxide(ZnO)to Mineral Trioxide Aggregate(MTA)has been shown to rectify tooth discoloration caused by Angelus MTA.This study evaluated the microhardness,compressive strength,calcium ion release and crystalline structures of MTA mixed with ZnO in different environmental conditions.Molds with a diameter of 4 mm and a height of 6 mm were used for compressive strength,calcium ion release and X-ray diffraction(XRD)evaluations.Molds with 6 mm diameter and 4 mm height were used for surface microhardness evaluations.Cements evaluated include Angelus MTA(Angelus,Brail),Angelus MTA+ZnO,ProRoot MTA(Dentsply Tulsa Dental,OK),and ProRoot MTA+ZnO.Each group was divided into 3 subgroups according to exposure conditions:normal saline(NS),phosphate buffered saline(PBS)or blood.After 7 days incubation,surface microhardness,compressive strength and XRD analysis was performed.Calcium ion release was evaluated after 3,24 and 168h incubation using atomic absorption spectrophotometry.Data were analyzed by One Way Anova followed by the Tukey HSD Post hoc tests and T-Test.The significance level was set at 0.05.Addition of ZnO to Angelus and ProRoot MTA significantly decreased the compressive strength of these cements regardless of the environmental conditions(P<0.001);however,it had no significant effect on their microhardness or calcium ion release.In conclusion,adding ZnO to Angelus and ProRoot MTA can adversely affect the compressive strength of Angelus and ProRoot MTA.