Bioceramic versus traditional biomaterials for endodontic sealers according to the ideal properties

Odontology, as a scientific discipline, continuously collaborates with biomaterials engineering to enhance treatment characteristics and patients' satisfaction. Endodontics, a specialized field of dentistry, focuses on the study, diagnosis, prevention, and treatment of dental disorders affecting the dental pulp, root, and surrounding tissues. A critical aspect of endodontic treatment involves the careful selection of an appropriate endodontic sealer for clinical use, as it significantly influences treatment outcomes. Traditional sealers, such as zinc oxide-eugenol, fatty acid, salicylate, epoxy resin, silicone, and methacrylate resin systems, have been extensively used for decades. However, advancements in endodontics have given rise to bioceramic-based sealers, offering improved properties and addressing new challenges in endodontic therapy. In this review, a classification of these materials and their ideal properties are presented to provide evidence-based guidance to clinicians. Physicochemical properties, including sealing ability, stability over time and space, as well as biological properties such as biocompatibility and antibacterial characteristics, along with cost-effectiveness, are essential factors influencing clinicians' decisions based on individual patient evaluations.

Subcutaneous tissue reaction to a novel nano zinc oxide eugenol dental cement

BACKGROUND

Zinc oxide eugenol (ZOE) cement is a popular dental material due mainly to its analgesic, antibacterial and anti-inflammatory effects. The formulation of ZOE cement from nano particle-sized zinc oxide (ZnO) has the potential to increase these properties as well as reduce its adverse effects to the surrounding tissues.

OBJECTIVE

This study evaluated the subcutaneous tissue response towards nano ZOE cements (ZOE-A and ZOE-B) in comparison to conventional ZOE (ZOE-K).

METHODS

Test materials were implanted into 15 New Zealand white rabbits. Tissue samples were obtained after 7, 14, and 30 days (n = 5 per period) for histopathological evaluation of inflammatory cell infiltrate, fibrous tissue condensation, and abscess formation.

RESULTS

ZOE-A showed the lowest score for the variable macrophage and lymphocyte at day 7. Both ZOE-A and ZOE-B presented lower fibrous tissue condensation and abscess formation compared to conventional ZOE-K. By day 30, ZOE-A exhibited less lymphocytic and neutrophilic infiltrate compared to the other materials, while ZOE-B had the lowest score for macrophages. ZOE-K exerted higher inflammatory cell response at almost all of the experimental periods. All of the materials resulted in thin fiber condensation after 30 days.

CONCLUSIONS

Rabbit tissue implanted with ZOE-A and ZOE-B showed better response compared to ZOE-K.

Primary Tooth Vital Pulp Treatment Interventions: Systematic Review and Meta-Analyses

Purpose: to update the 2016 systematic review evidence for vital pulp therapy (VPT) for primary teeth affected by caries or trauma. Methods: The population, intervention, comparison, outcomes, and study (PICOS) design inclusion/exclusion was used for multiple databases. Risk of bias, meta-analyses using RevMan, and certainty of evidence was created. Results: A total of 299 studies were included; no trauma was found. Indirect pulp treatment (IPT) resulted in 97 percent success. Two calcium silicate cement (CSC) pulpotomies' success using mineral trioxide aggregate (MTA) and Biodentine® were 94 percent and 90 percent, respectively, greater than for direct pulp capping (DPC; 86 percent) and other pulpotomies (moderate certainty). The success of IPT versus pulpotomy at 24 months showed no significant difference (P=0.31). Different liners or capping agents did not affect the success of IPT (P=0.79) or DPC at 24 months (P=0.24). The two CSC pulpotomies were not significantly different based on 24-month success (P=0.34). The formocresol pulpotomy success at 24 months was significantly lower than for MTA (P=0.02). Ferric sulfate had a significant lower success at 24 months than MTA pulpotomy (69 percent versus 92 percent; P=0.03). Zinc oxide eugenol, as a singular pulpotomy, had low success (65 percent). Selective/stepwise caries removal did significantly better at avoiding pulp exposures than complete excavation (P<0.001). Complete, selective, and no caries removal (Hall technique [HT], steel crown placement with no caries removal) had no significant difference in pulp vitality success for deep caries at 24 months (P=0.29). For deep caries affecting vital incisors, pulpotomy had significantly greater success than pulpectomy (P=0.002). The following had no significant effect on MTA pulpotomy success: coronal pulp removal methods; irrigation solution; method to control hemorrhage; base over MTA; treatment in one or two visits; and anterior or posterior teeth. Conclusions: Vital pulp therapy success of indirect pulp treatment or two calcium silicate cement pulpotomies demonstrated improved success over direct pulp capping and other pulpotomies based on 24-month evidence with moderate certainty. The Hall technique did not significantly reduce pulp vitality success versus caries removal.

An in vitro study of a custom-made device for thermoregulation of the mixing slab on the setting properties of zinc oxide eugenol impression paste

Aim

The present study was aimed to investigate the functional relationship between the mixing temperature and properties of a commercially available zinc oxide eugenol impression paste (ZnOE paste).

Settings and Design

In-vitro study.

Materials and Methods

A custom-made simulated mixing device was indigenously designed to maintain different mixing temperatures, simulating cold, ambient, and hot weather. A commercially available ZnOE paste was mixed according to the manufacturer's instructions in the simulated mixing device at the temperatures ranging from 10°C to 50°C. Initial setting time and consistency were measured according to A. D. A. Specification No. 16 (n = 8). A stainless-steel die having 25, 50, and 75 μm lines was used for surface detail reproduction. Detail reproduction of the stone casts of the impressions was evaluated with a stereomicroscope at 30 magnification (n = 8). The shear bond strength of ZnOE paste to self-cure acrylic tray resin was measured by using the UTM at a crosshead speed of 0.5 mm/min (n = 8).

Statistical Analysis Used

Data were analyzed by using one-way analysis of variance (ANOVA) and Tukey's post hoc tests at a confidence interval of 95% (alpha =0.05).

Results

Initial setting time, consistency, and detail reproduction of the ZnOE paste were affected by the mixing temperature (P < 0.001). Mixing ZnOE paste at a lower temperature of 10°C and higher temperatures of 40°C and 50°C resulted in shorter initial setting time, thicker consistency, and poor detail reproduction. However, no significant difference was obtained in the shear bond strength among the different mixing temperatures evaluated (P > 0.05).

Conclusion

Based on this in vitro study, it is advisable to perform the manipulation of ZnOE paste at a clinical/laboratory temperature of 30°C for optimum performance. The simulated mixing device used in this study can be an alternative for extreme climatic conditions.

One year clinical success of pulpectomy in primary molars with iodoform-calcium hydroxide paste

OBJECTIVES

In order to retain primary molars, eg with irreversible pulpitis or pulp necrosis, pulpectomy can be an alternative to extraction. However, reports on the success of pulpectomies in primary teeth vary widely in the literature. Thus, the objective of this study was not only to analyze the success rate of primary tooth pulpectomy 12 months posttreatment in the setting of a specialized clinic, but also to identify and analyze various factors that modify the outcome.

METHOD AND MATERIALS

Between 2012 and 2018, a total of 76 dental records of the Department of Preventive and Pediatric Dentistry at the University of Greifswald fulfilled the inclusion criteria, resulting in a 1-year analysis of 62 primary molars with an idoform-calcium hydroxide paste as root canal filling material almost exclusively covered by a stainless steel crown as restoration.

RESULTS

The pulpectomy treatment was successful after 1 year in 93.5%, with a significantly higher survival for mandibular primary molars (100.0% vs 83.3%; chi-square test P = .01). Apart from the very few cases in the mixed dentition, no other factors related to the patient (sex, caries level, general health conditions, distance to clinic), tooth (first or second primary molar, pulpal and periapical condition before treatment), or treatment (indication, academic qualification of the operator, number of visits) proved to be of significance for the treatment outcome due to the overall high success rate.

CONCLUSION

Pulpectomies for pulpally involved or even necrotic primary molars followed by stainless steel crowns as restoration should be considered as a treatment option, especially in the mandible. (Quintessence Int 2021;52:528-537; doi: 10.3290/j.qi.b1244443).

Are different pulp treatment techniques and associated medicaments effective for the treatment of extensive decay in primary teeth?

Data sources Cochrane Oral Health's Trials Register and Central Register of Controlled Trials, Medline Ovid, Embase Ovid, Web of Science, Open Grey, US National Institutes of Health Ongoing Trials Register and World Health Organisation International Clinical Trials Registry Platform. There were no restrictions on language or publication dates.Study selection Two reviewers selected randomised clinical trials (RCTs) comparing different pulp interventions in extensively decayed primary teeth, which combined a pulp treatment technique and a medicament.Data extraction and synthesis Data were extracted independently by two reviewers recording year of publication, country of origin, inclusion/exclusion criteria, description of interventions, sample size, mean age, duration of follow-up and outcome data. Risk of bias was assessed by two reviewers. Meta-analysis was performed on RCTs comparing different medicaments for the same pulp technique or different pulp treatment techniques with each other.Results Eighty-seven RCTs were included in qualitative synthesis, yielding 59 studies for meta-analysis. The 87 RCTs involved 7,140 randomised teeth with 17 split-mouth RCTs and 70 parallel arm design. In total, 125 different comparisons were examined using clinical and radiological failure rates; 75 compared different pulpotomy agents or techniques, 25 compared different pulpectomy agents, four compared pulpotomy and pulpectomy, and 21 compared different agents for direct pulp capping. Where possible, data were compared for 6, 12 and 24 months. For pulpotomy, mineral trioxide aggregate (MTA) appears least likely to fail over those time periods. For pulpectomy, results were inconclusive comparing failure rates between various agents; however, two RCTs found a lower failure rate for zinc oxide-eugenol (ZOE) compared with Vitapex. For direct pulp capping, there was a low number of studies undertaking the same comparisons; calcium silicates (eg MTA and Biodentine) hold future promise.Conclusions Overall, evidence quality ranged from moderate to very low. For pulpotomy, MTA may be the best pulpotomy medicament in primary molars. Formocresol is effective but generally accepted as toxic. Biodentine, enamel matrix derivatives, laser application or Ankaferd Blood Stopper (a plant-based haemostatic agent used to control gastrointestinal bleeds) appear to be second choices. If all of these are unavailable, an application of sodium hypochlorite may be the safest option. For pulpectomy, evidence was inconclusive; however, ZOE paste may be more effective than Vitapex, but no further conclusions could be made. For direct pulp capping, the evidence was of low to very low quality. The best alternative may be a tricalcium silicate, especially MTA. Future RCTs may change these findings.

Manoeuvrability and biocompatibility of endodontic tricalcium silicate-based putties

OBJECTIVES

The present study evaluated the indentation depth, storage modulus and biocompatibility of an experimental endodontic putty designed for endodontic perforation repair and direct pulp-capping (NeoPutty). The results were compared with the properties associated with the commercially available EndoSequence BC RRM Putty (ES Putty).

METHODS

Indentation depth was measured by a profilometer following indentation with the 1/4 lb Gilmore needle. Elastic modulus was evaluated using a strain-controlled rheometer. The effects of eluents derived from these two putties were examined on the viability and proliferation of human dental pulp stem cells (hDPSCs) and human periodontal ligament fibroblasts (hPDLFs), before (1 st testing cycle) and after complete setting (2nd testing cycle).

RESULTS

The ES Putty became more difficult to ident and acquired a larger storage modulus after exposure to atmospheric moisture. Biocompatibility results indicated that both putties were relatively more cytotoxic than the bioinert Teflon negative control, but much less cytotoxic than the zinc oxide-eugenol cement negative control. NeoPutty was less cytotoxic than ES putty in the 1st testing cycle, particularly with hDPSCs. Both putties exhibited more favourable cytotoxicity profiles after complete setting.

CONCLUSIONS

NeoPutty has a better window of maneuverability after exposure to atmospheric moisture. From an in vitro cytotoxicity perspective, the NeoPutty may be considered more biocompatible than ES putty.

CLINICAL SIGNIFICANCE

The experimental NeoPutty is biocompatible and is capable of reducing the frustration of shortened shelf life when jar-stored endodontic putties are exposed to atmospheric moisture during repeated opening of the lid for clinical retrieval.

A Systematic Review and Meta-Analysis of Nonvital Pulp Therapy for Primary Teeth

Purpose: The purpose of this systematic review and meta-analysis was to assess success rates for nonvital treatment in primary teeth for caries/trauma. Methods: Databases were searched between 1960 and 2020 for randomized controlled trials, cohorts, case series, and in vitro studies. The primary outcome was overall success (clinical and radiographic) for pulpectomy and lesion sterilization tissue repair (LSTR). Included articles were independently determined, agreed upon, data extraction assessed, risk of bias, meta-analyses, and assignment of quality of evidence (GRADE). Results: Comparing teeth with and without root resorption, pulpectomy success was better (P<0.001) in teeth without preoperative root resorption. Success with pulpectomies performed with zinc oxide eugenol [ZOE] and with Endoflas (ZOE plus iodoform plus calcium hydroxide) did not differ from that observed using Vitapex or Metapex (iodoform plus calcium hydroxide; P≥0.50) after 18 months; however, Endoflas and ZOE success rates remained near 90 percent versus 71 percent or less for iodoform. Network analysis ratings showed Endoflas and ZOE performed better than iodoform alone. Also, LSTR performed better (P<0.001) than pulpectomies in teeth with preoperative root resorption, but pulpectomy results were superior (P=0.09) if roots were intact. Rotary instrumentation of root canals was significantly faster (P<0.001) than manual instrumentation. Success rates were not impacted by method of obturation or root length determination, type of tooth, number of visits, irrigants, smear layer removal, or timing/type of final restoration. Conclusions: Eighteen-month success rates support Endloflas and zinc oxide eugenol pulpectomies over iodoform pulpectomies. Lesion sterilization tissue repair had limited indication for teeth with resorbed roots.

Fracture Resistance of Roots Filled With Bio-Ceramic and Epoxy Resin-Based Sealers: In Vitro Study

Objective

This study aimed to assess the resistance of roots to fracture after being root canal filled with two types of endodontic sealers; bio-ceramic based sealer (TotalFill) and epoxy-resin based sealer (AH Plus).

Methods

Fifty-nine single canal mandibular premolars were instrumented. Group I (n=14, negative control): root canals were left without instrumentation and unfilled, group II (n=15, positive control): root canals were instrumented only and left unfilled, group III and IV (n=15 each): root canals were instrumented and filled with either gutta-percha/TotalFill or gutta-percha/AH Plus, respectively. The resistance of the roots to fracture was measured with a universal testing machine "Instron Corp" through recording the maximum force in Newton (N) needed to fracture each root. To analyze the data Kruskal-Wallis test was utilized, followed by Dunn's Bonferroni post hoc test for multiple comparisons. The level of significance was set at 0.05 (P≤0.05).

Results

TotalFill group showed slightly better fracture resistance (734.62 N) than AH Plus group (728.29 N). However, no statistical significant difference was found between the two groups (P>0.05). The greatest mean fracture force was shown in the negative control group (913.915 N) with statistical significant difference between the other three groups (P<0.05).

Conclusion

Gutta-percha/TotalFill and gutta-percha/AH Plus did not reinforce the root canal treated teeth.

Linear Dimensional Changes of Five Interocclusal Recording Materials When Immersed in Two Disinfectants for Different Time Intervals

AIM

In this study, we intend to compare the linear dimensional changes of interocclusal recording media by immersing them in disinfectant solutions at different time intervals.

MATERIALS AND METHODS

Five interocclusal recording materials were used for this study and were grouped according to material types, namely wax, zinc oxide eugenol impression paste, polyether, polyvinyl siloxane, and bisacryl bite registration material. Each material was manipulated and injected into a stainless steel die. The materials were divided into 5 groups with 5 subgroups of 10 samples with a total of 250 samples. The samples were subjected to immersion in 2% glutaraldehyde and 0.5% sodium hypochlorite each for 30 and 60 minutes. Linear dimensional changes of the samples were tested by measuring the distance between points A and B at different time intervals by means of a stereomicroscope and compared with the control group.

RESULTS

Bisacryl showed the least linear dimensional change when immersed in both the solutions.

CONCLUSION

Bisacryl (Luxabite) presented no linear dimensional change at both time intervals as opposed to the other materials, hence, it is most accurate.

Comparative analysis of microleakage of temporary filling materials used for multivisit endodontic treatment sessions in primary teeth: an in vitro study

PURPOSE

Coronal leakage is an important factor contributing to the failure of endodontic treatment. The use of an efficient temporary restoration between sessions of multiple-visit pulpectomies is irrefutable. Two cements have long been used in endodontics-IRM, which is a reinforced zinc oxide cement and Cavit G, a calcium sulphate based cement. The aim of this study was to compare the microleakage of nano silver containing UDMA-based cements with routinely used zinc oxide and calcium sulphate-based temporary cements in primary teeth.

METHODS

Standardized access cavities of 3 × 3 mm were prepared in the sixty caries-free primary molars. The teeth were divided randomly into four groups of 14 teeth each-Group I: IRM, Group II: Cavit G, Group III: Orafil-G and Group IV: Dia-Temp. Temporary restorative materials were applied according to the manufacturer's instructions. The teeth were subjected to thermocycling and then immersed in 0.5% basic fuchsin for 24 h. The specimens were sectioned and evaluated under a digital microscope at 20× magnification and were scored for microleakage. The collected data were tabulated and subjected to statistical analysis.

RESULTS

Dia-Temp presented the least microleakage values. The highest score for microleakage was shown by IRM followed by Orafil-G and Cavit-G. There was a significant difference between IRM and Diatemp groups (p value = 0.009), and among Orafil G and Diatemp groups (p value = 0.025).

CONCLUSION

Among the four materials tested, Dia-Temp exhibited the best sealing ability and its use is recommended in between sessions of endodontic treatment in primary teeth.

Effect of Overlying Material on Final Setting of Biodentine ® in Primary Molar Pulpotomies

Purpose: The purpose of this study was to evaluate and compare in vitro the effect of overlying materials, including zinc oxide eugenol (ZOE), resin-modified glass ionomer cement (RMGIC), and stainless steel crowns (SSC) cemented with glass ionomer cement (GIC), on the setting of Biodentine ® (BD) used as a pulpotomy agent in primary molars that were restored definitively in a single visit. Methods: Forty extracted primary molars were prepared to replicate pulpotomy procedures. The teeth were randomly allocated to four restorative groups: (1) BD, ZOE, SSC; (2) BD, RMGIC, SSC; (3) BD, SSC; (4) BD only (control). All samples were incubated for 24 hours, sectioned mesial-distally, and polished. BD setting was measured as a function of Knoop hardness value (HK) using a Leco Microhardness Tester. Each sample was tested in three zones with 50 gf load force and 30 seconds dwell time and at one, two, and three mm distance from the BD-material interface. A one-way analysis of variance was used to determine statistical significance between groups (P<.05). Results: There was no statistically significant difference between the mean HK value among the four groups and three zones. Conclusions: Overlying materials, including zinc oxide eugenol, resin-modified glass ionomer, and stainless steel crowns cemented with glass ionomer cement, showed no effect on the BD final set. This in vitro study found no evidence against immediate definitive restoration of Biodentine ® pulpotomies.

Effects of Restorative Materials on Dental Pulp Stem Cell Properties

INTRODUCTION

Dental pulp stem cells (DPSCs) are multipotent progenitors for biotechnological practices, but the influences of existing restorations on their viability and differentiation are not well-known. This study was aimed to investigate in vivo and in vitro responses of DPSCs to restorative materials.

METHODS

Class I cavities were prepared on molars scheduled to be extracted and then restored with a resin-based composite (RBC), a glass ionomer cement, or zinc oxide eugenol. Intact teeth were used as controls. Twelve molars in each group were extracted on day 7 or day 30 after restorations to assess the early or intermediate pulp responses and were then cut in half. One half was processed for histopathological analysis, and the other was used to isolate DPSCs for a colony-forming unit assay and real-time polymerase chain reaction for NANOG, OCT4, and CD44 expression.

RESULTS

All restored teeth showed pulp damage at various levels, whereas mild to moderate inflammation persisted in the RBC group until day 30. The existence of DPSCs in the pulp cores of all groups was revealed based on CD44 immunoreactivity. Glass ionomer cement and zinc oxide eugenol did not affect the relative percentages of DPSCs in either early or intermediate stages, whereas RBCs reduced the percentage. The colony-forming units in all restoration groups were comparable with those in the control. Nevertheless, the restorations significantly enhanced OCT4 expression, especially in RBC/day 30.

CONCLUSIONS

Dental restorations cause mild pulp damage but do not affect DPSC viability. RBC decreases DPSC densities but might increase the stemness of surviving DPSCs through an inflammation-stimulation process.

[Histological evaluation of inflammatory response to zinc-oxide-eugenol filling materials in a soft and bone tissues]

AIM

To evaluate and to compare the intensity of the inflammatory response to zinc-oxide-eugenol based filling material in rabbit's soft and bone tissue.

MATERIAL AND METHODS

The study employed 20 chinchilla rabbits. The artificial defects were formed in jaw and in soft tissues and filled by zinc-oxide-eugenol based filling material. After 14 or 30 days the animals were euthanized, and tissue samples were analyzed with microscope.

RESULTS

Histological analysis revealed that zinc-oxide-eugenol based filling material support inflammation reaction in the tissue, but bone tissue showed statistically lower inflammatory response in comparison to soft tissue (p<0,05).

CONCLUSION

Extrusion of zinc-oxide-eugenol based filling material from root canal is undesirable as it leads to complex unfavorable tissue reaction for its elimination, more pronounced in soft tissues.

Effect of radiotherapy on the coronal-sealing ability of two different root canal sealing materials

OBJECTIVE

This study aimed to assess the coronal-sealing ability of two different root canal obturation materials: gutta-percha with AH Plus and Resilon with Epiphany SE between radiated and nonirradiated groups.

MATERIALS AND METHODS

Fifty-six extracted premolar teeth were randomly divided into two main groups according to the presence or absence of radiotherapy. Specimens were divided into two equal groups. In the radiotherapy group, a total dose of 60 Gy was delivered with 1.8 Gy/d fractions, 5 days a week, for 35 days. The root canals were obturated with either gutta-percha/AH Plus or Resilon/Epiphany SE canal sealer. The samples were then evaluated for the coronal-sealing ability using a centrifuging dye penetration test at 3000 rpm for 5 min in a 2% Rhodamine B solution. The degree of dye penetration was evaluated with a stereomicroscope.

RESULTS

Although the sealing ability of both groups was not affected in radiotherapy, the coronal leakage values of Resilon/Epiphany SE slightly increased when radiation was applied (P > 0.05).

CONCLUSION

Radiotherapy does not significantly affect the coronal-sealing ability of root canal obturation materials, gutta-percha/AH Plus and Resilon/Epiphany SE.

Non-hermetic encapsulation for implantable electronic devices based on epoxy

Hermetic and non-hermetic implant packaging are the two strategies to protect electronic systems from the humid conditions inside the human body. Within the scope of this work twelve different material combinations for a non-hermetic, high-reliable epoxy based encapsulation technique were characterized. Three EPO-TEK (ET) epoxies and one low budget epoxy were chosen for studies with respect to their processability, water vapor transmission rate (WVTR) and adhesion to two different ceramic-based substrates as well as to one standard FR4-substrate. Setups were built to analyze the mentioned properties for at least 30 days using an aging test in a moist environment. As secondary test subjects, commercially available USB flash drives (UFD) were successfully encapsulated inside the epoxies, soaked in phosphate buffered saline (PBS, pH=7.4), stored in an incubator (37°C) and tested for 256 days without failure. By means of epoxy WVTR (0.0278 g/day/m(2)) and degrease of adhesion (24.59 %) during 30 days in PBS, the combination of the standard FR4-substrate and the epoxy ET 301-2 was found to feature the best encapsulation properties. If a ceramic-based electronic system has to be used, the most promising combination consists of the alumina substrate and the epoxy ET 302-3M (WVTR: 0.0588 g/day/m(2); adhesion drop: 49.58 %).

Assessment of Coronal Leakage of Temporary Restorations in Root Canal-treated Teeth: An in vitro Study

INTRODUCTION

Coronal leakage is one of the constant concerns in routine dental practice. It is one of the factors responsible for the failure of root canal therapy. Permanent restorations should be given as soon as possible after the completion of root canal therapy. If unavoidable, provisional restoration should be given in such a way that it maximally reduced the leakage of microorganisms and fluids from the external environment into the canal space. Hence, we evaluated the effect of saliva on the coronal leakage of temporary restorations.

MATERIALS AND METHODS

Biomechanical preparation of the root canals of 204 fresh mandibular first premolar teeth was done using endodontic files with intermittent irrigation of sodium hypochlorite solution and ethylenediaminetetraacetic acid. Alternate irrigation with normal saline was done periodically. After preparation, drying of the canals was done using paper points followed by sealing of the apical foramen. For the assessment of the microleakage, Siqueira et al apparatus and method was used. All the specimens were divided into four groups based on the provisional restorative material used. All the groups were further divided into three subgroups based on the presence and absence of intracanal medicaments. Verissimo et al's criteria were used to check the turbidity at 1-, 2-, 3-, and 4-week interval respectively. All the results were analyzed by Statistical Package for the Social Sciences (SPSS) software. Chi-square test was used to measure the level of significance, and p < 0.05 was considered to be significant.

RESULTS

In group I, all the subgroups' specimens showed significant difference at 1 week's time. Only the subgroup with no intracanal medicaments in Cavit-containing provisional restoration showed nonsignificant alterations. Statistically significant alterations were seen at 1, 2, and 3 weeks' interval in all the subgroups except for one with intracanal medicaments.

CONCLUSION

All the temporary restorative materials were not able to prevent microleakage after 1 week's time, with worst bacterial resistance shown by Ketac Molar and ionomer restorative material. Future studies are advocated for better prognosis of root canal therapy.

Effectiveness of 4 Pulpotomy Techniques—Randomized Controlled Trial

Pulpotomy is the accepted therapy for the management of cariously exposed pulps in symptom-free primary molars; however, evidence is lacking about the most appropriate technique. The aim of this study was to compare the relative effectiveness of the Er:YAG laser, calcium hydroxide, and ferric sulfate techniques with that of dilute formocresol in retaining such molars symptom-free. Two hundred primary molars in 107 healthy children were included and randomly allocated to one of the techniques. The treated teeth were blindly re-evaluated after 6, 12, 18, and 24 months. Descriptive data analysis and logistic regression analysis, accounting for each patient’s effect by a generalized estimating equation (GEE), were used. After 24 months, the following total and clinical success rates were determined (%): formocresol 85 (96), laser 78 (93), calcium hydroxide 53 (87), and ferric sulfate 86 (100). Only calcium hydroxide performed significantly worse than formocresol (p = 0.001, odds ratio = 5.6, 95% confidence interval 2.0–15.5). In conclusion, calcium hydroxide is less appropriate for pulpotomies than is formocresol.

[Root canal treatment of mandibular first premolar with 4 root canals: a case report]

The mandibular first premolar can be considered one of the most challenging teeth to treat, due to the complexity of its root canal morphology and increased incidence of multiple canals. A case of endodontic treatment of a mandibular first premolar exhibiting a total of 4 distinct root canals and 4 apical foramina was described. Anatomic variation of root canal morphology should be considered in endodontic treatment to ensure a favorable healing outcome, and its identification could be enhanced by careful examination using a dental operating microscope. Obturation of root canals using a warm vertical compaction technique with a highly-radiopaque root canal sealer, such as AH Plus, after careful ultrasonic activated irrigation might allow the flow of sealer into the narrowed but unprepared part of the canal, thereby facilitating optimum chemo-mechanical debridement of the root canal system.

[Degradation evaluation and success of pulpectomy with a modified primary root canal filling in primary molars]

OBJECTIVE

To compare clinical and radiographic success rates of a modified primary root canal filling (ingredients: zinc oxide-eugenol, iodoform and calcium hydroxide, MPRCF) vs. zinc oxide-eugenol cement (ZOE) and calcium hydroxide/iodoform paste (Vitapex) in pulpectomized primary molars at the end of 6 and 12 months, and to evaluate the degradation of materials in the root canals and in apical area.

METHODS

In the study, 160 primary molars from 155 children (the average age: 5.88±1.27 years) that met the inclusion criteria were allocated to one of the three materials via block randomization. A two-visit pulpectomy was performed by an investigator. The clinical and radiographic diagnoses were blindly assessed by other two investigators.

RESULTS

At the end of 6 and 12 months, the ZOE and MPRCF success rates were 100% both in clinical and radiographic evaluation. The Vitapex group showed the clinical success of 100% at the end of 6 months and 94.5% at the end of 12 months. Radiographic evaluation for the Vitapex group showed 80.4% success at the end of 6 months and 60.7% at the end of 12 months. No statistically significant differences were noted at the end of 6 months in the three groups both in clinical and radiographic evaluation. The success rates in clinical and radiographic evaluation at the end of 12 months for ZOE and MPRCF groups were not significantly different, and better than those for Vitapex group with statistically significant difference. The completely resorb rate of excess extruded extraradicularly were 14.3%, 100% and 71.4% for ZOE, Vitapex and MPRCF at the end of 12 months. The rates of resorption of material at the same rate of the root were 5.8%, 7.2% and 40.9% for ZOE, Vitapex and MPRCF at the end of 12 months.

CONCLUSION

MPRCF, a mixture of zinc oxide eugenol and iodoform with calcium hydroxide can be used as a root canal filling material in primary teeth, taking account of the success rate and resorbing at a similar rate with the roots of the primary teeth.

Hermetic diamond capsules for biomedical implants enabled by gold active braze alloys

As the field of biomedical implants matures the functionality of implants is rapidly increasing. In the field of neural prostheses this is particularly apparent as researchers strive to build devices that interact with highly complex neural systems such as vision, hearing, touch and movement. A retinal implant, for example, is a highly complex device and the surgery, training and rehabilitation requirements involved in deploying such devices are extensive. Ideally, such devices will be implanted only once and will continue to function effectively for the lifetime of the patient. The first and most pivotal factor that determines device longevity is the encapsulation that separates the sensitive electronics of the device from the biological environment. This paper describes the realisation of a free standing device encapsulation made from diamond, the most impervious, long lasting and biochemically inert material known. A process of laser micro-machining and brazing is described detailing the fabrication of hermetic electrical feedthroughs and laser weldable seams using a 96.4% gold active braze alloy, another material renowned for biochemical longevity. Accelerated ageing of the braze alloy, feedthroughs and hermetic capsules yielded no evidence of corrosion and no loss of hermeticity. Samples of the gold braze implanted for 15 weeks, in vivo, caused minimal histopathological reaction and results were comparable to those obtained from medical grade silicone controls. The work described represents a first account of a free standing, fully functional hermetic diamond encapsulation for biomedical implants, enabled by gold active alloy brazing and laser micro-machining.

A microcomputed tomography-based comparison of root canal filling quality following different instrumentation and obturation techniques

OBJECTIVE

With a microcomputed tomography (microCT) imaging device, we aimed to quantitatively evaluate root canal fillings after commonly used endodontic procedures and also tested the suitability of microCT for this purpose.

MATERIALS AND METHODS

Eighty single roots were instrumented and obturated with gutta-percha and Tubli-Seal. They were divided into 4 groups of 20. The Hand groups were instrumented with hand files and filled with thermoplastic (Th) compaction and cold lateral (CL) condensation, i.e. Hand-Th and Hand-CL, respectively. The Rot groups, i.e. Rot-Th and Rot-CL, were instrumented with a rotary ProFile system and filled as above. The roots were scanned and 3-dimensional (3D) visualization was obtained. The number, size, percentage of volume and distribution of voids at the filling/dentine interface (i-voids) and voids surrounded by filling material (s-voids) were measured.

RESULTS

Canal fillings differed significantly with regard to the size of both types of voids and the average number of i-voids. All canals presented a low volume of voids. The highest percentage (0.69%) was found for i-voids in the Hand-CL group, while the lowest volume (0.11% for s-voids and 0.14% for i-voids) was in the Hand-Th canals. Apically, in the last 3 mm, i-voids were observed mainly in the Th groups, and s-voids occurred mostly in the coronal part of the canal filling in all cases.

CONCLUSION

MicroCT was a useful tool for 3D quantitative evaluations of these root canal fillings. None of the root canal instrumentation and filling methods ensured void-free obturation. CL condensation produced mainly i-voids. With Th compaction, internal s-voids were particularly common, but there were mainly i-voids in the apical part.

Comparison of different obturation techniques for primary molars by digital radiography

PURPOSE

The purpose of this study was to compare six methods of root canal filling in primary mandibular second molars via digital radiography.

METHODS

A total of 239 canals were prepared and obturated with zinc-oxide eugenol paste. Obturation methods compared were: anesthetic syringe; NaviTip syringe; pressure syringe; tuberculin syringe; lentulo spiral; and packing with a plugger. The canals were evaluated in photostimulated phosphor radiographs for length of obturation, presence of voids, and number and sum of void sizes. The data were analyzed using chi-square, Kruskal-Wallis and Mann-Whitney tests.

RESULTS

There were significant differences between all groups in the length of obturation (P>.01) and presence of voids (P<.001). The lentulo and tuberculin syringe groups, respectively, showed the best and worst results for length of obturation. Significant differences were also found in the number of voids (P<.001) and mean sum of void sizes in the coronal (P<.001) and middle third (P=.003). For the number and size of the voids, the NaviTip group showed the best results.

CONCLUSION

Lentulo produced the best results in terms of length of obturation, while NaviTip syringe produced the best results in controlling paste extrusion from the apical foramen and having the smallest void size and lowest number of voids.

[Study on apical sealing ability of iRoot SP root canal sealer]

PURPOSE

To evaluate the apical sealing ability of two root canal sealers.

METHODS

Fifty recently extracted human anterior teeth with a single canal (α<5; Schneider's method) were divided randomly into two experimental groups(twenty teeth in each group), as well as positive and negative control group (five teeth in each group). The root canals were instrumented using Protaper file to F2, and were obturated with iRoot SP with continuous wave obturation technique (group A), AH plus with continuous wave obturation technique (group B). The apical microleakage was evaluated by dye penetration method. Linear dye penetration was measured and analyzed by SPSS13.0 software package.

RESULTS

Mean depth of leakage for groups with the smear layer intact was (1.46±0.21) mm for group A, (1.52±0.22) mm for group B, (10.75±1.28) mm for positive control group, and 0 mm for negative control group. The value of the experimental group B was greater than group A, but there was no significant difference between the 2 groups.

CONCLUSION

iRoot SP displays similar in vitro apical sealing ability to AH plus.

[A quantitative glucose method by constant air pressure for evaluating the sealing ability of four root canal sealers]

OBJECTIVE

To introduce a modified model for quantitative testing of glucose microleakage by constant air pressure and evaluate the sealing ability of four root canal sealers including AU Plus, Roeko Seal, Cortisomol and RC Sealer.

METHODS

Fifty-six straight maxillary anterior teetb were randomly divided into four experimental groups with 12 samples in each group, group A: AH Plus, group B: Roeko Seal, group C: Cortisomol, group D: RC Sealer, and positive and negative control group with 4 samples in each. After regular root preparation, samples in experimental groups were obturated by cold gutta-percha lateral compaction technique with sealers according to group description. Control groups were obturated with cold gutta-percha only. Through the model above, the value of glucose microleakage from crown to root was measured at 1, 3, 5, 7, 10, 15, 20, 25, 30 days with the glucose oxidase-peroxidase method (GOD-POD).

RESULTS

At day 1, 3, 5, no significant difference of microleakage was found between group A and B (P > 0.05). The same result was also seen between group C and D. From 7 days, microleakage value in each experimental group gradually increased, and statistical difference was found between groups (P < 0.05).

CONCLUSION

This new model using constant air pressure is easy to establish, sensitive and practical. Among all the sealers evaluated, polydimethylsiloxane based root canal sealer, Roeko Seal has the greatest sealing ability, while epoxy-amine resin based AH Plus is second and Zinc Oxide based Cortisomol and RC Sealer have the least sealing ability.

Volumetric analysis of root canal fillings in primary teeth using spiral computed tomography: an in vitro study

PURPOSE

The purpose of this study was to volumetrically analyze the efficacy of root canal fillings in primary teeth using spiral computed tomography (CT).

METHODS

Root canals in 30 primary maxillary and mandibular molars were instrumented with K files to size 30, and the volumes of the canals were then measured using spiral CT. The teeth were randomly divided into 3 groups of 10 each, and 18 of the canals in each group were evaluated with spiral CT after obturation with zinc oxide eugenol paste, Metapex and Vitapex. The filled volume in each canal was mea- sured using spiral CT, and the percentage of obturated volume (POV) was calculated. The pre- and post-mean canal volume values within each group and the POV of the 3 groups were statistically analyzed using one-way analysis of variance and paired t tests.

RESULTS

Filler voids were seen in all groups, but there was a statistically significant difference (P <.001) in the calculated POV. Vitapex showed 95% POV compared to Metapex (88%) and ZOE (84%).

CONCLUSION

Voids were seen in all 3 filling materials. Vitapex showed the maximum percentage of obturated volume among the 3 groups.

A 232-channel retinal vision prosthesis with a miniaturized hermetic package

Miniaturization of implantable devices while drastically increasing the number of stimulation channels is one of the greatest challenges in implant manufacturing because a small but hermetic package is needed that provides reliable protection for the electronics over decades. Retinal vision prostheses are the best example for it. This paper presents a miniaturized 232-channel vision prosthesis, summarizing the studies on the individual technologies that were developed, improved and combined to fabricate a telemetrically powered retinal device sample. The implantable unit, which is made out of a high temperature co-fired alumina ceramic package containing hermetic feedthroughs, electronic circuitry and a radio frequency coil for powering is manufactured through a modified screen-printing/lasering process. The package is sealed with solder glass to provide unaffected inductive coupling to the telemetric transmitter. A 0.05 cc inner volume allows helium leak testing and mathematical lifetime estimations for moisture-induced failure of up to 100 years. The feedthroughs contact a thin-film polyimide electrode array that utilizes DLC and SiC coatings for improved interlayer adhesion of the metallic tracks to the polymer carrier. Two metal layers allow integrated wiring of the electrode array within the very limited space.

[Effects of two endodontic sealers on the bond strength of two fiber posts]

OBJECTIVE

To study the effects of two different endodontic sealers on the bond strength of two fiber posts cemented with adhesive resin cement.

METHODS

Twenty-eight crownless human maxillary central incisors were prepared with the step-back technique and randomly divided into four groups according endodontic sealer and fiber: Group A, Cortisomol sealer+Matchpost fiber post; Group B, Cortisomol sealer+Macrolock fiber post; Group C, Guttaflow sealer+Matchpost fiber post; Group D, Guttaflow sealer+Macrolock fiber post. One week after fiber posts were bonded, a thin-slice push-out test was performed in a universal machine. Morphologic structure of the root canal dentin surfaces etched and the adhesive interfaces were examined by scanning electron microscopy (SEM).

RESULTS

The bond strengths of 4 groups were (7.06 +/- 3.22), (9.31 +/- 3.61), (6.90 +/- 3.13), (9.71 +/- 3.42) MPa. The bond strengths of group B and D were significantly higher than that of group A and C (P < 0.05). There was no significant difference between group A and C, group B and D (P > 0.05). The cervical third had the highest mean push-out bond strength, next to middle third and apical third (P < 0.01). SEM showed that larger numbers of the dentin tubules were open after the root canals were etched and penetration of resin tags into the dentinal tubules increased in the coronal root region when compared with the apical root region.

CONCLUSION

The shear bond strength doesn't have relationship with endodontic sealers. The serration significantly increases the retention of fiber post. The bond strengths are different at the three root segment sites.

Evaluation of pH at the bacteria-dental cement interface

Physiochemical assessment of the parasite-biomaterial interface is essential in the development of new biomaterials. The purpose of this study was to develop a method to evaluate pH at the bacteria-dental cement interface and to demonstrate physiochemical interaction at the interface. The experimental apparatus with a well (4.0 mm in diameter and 2.0 mm deep) was made of polymethyl methacrylate with dental cement or polymethyl methacrylate (control) at the bottom. Three representative dental cements (glass-ionomer, zinc phosphate, and zinc oxide-eugenol cements) were used. Each specimen was immersed in 2 mM potassium phosphate buffer for 10 min, 24 hrs, 1 wk, or 4 wks. The well was packed with Streptococcus mutans NCTC 10449, and a miniature pH electrode was placed at the interface between bacterial cells and dental cement. The pH was monitored after the addition of 1% glucose, and the fluoride contained in the cells was quantified. Glass-ionomer cement inhibited the bacteria-induced pH fall significantly compared with polymethyl methacrylate (control) at the interface (10 min, 5.16 ± 0.19 vs. 4.50 ± 0.07; 24 hrs, 5.20 ± 0.07 vs. 4.59 ± 0.11; 1 wk, 5.34 ± 0.14 vs. 4.57 ± 0.11; and 4 wks, 4.95 ± 0.27 vs. 4.40 ± 0.14), probably due to the fluoride released from the cement. This method could be useful for the assessment of pH at the parasite-biomaterial interface.

Long-term outcomes of primary tooth pulpectomy with and without smear layer removal: a randomized split-mouth clinical trial

PURPOSE

The aim of this study was to evaluate, via clinical and radiographic assessment, pulpectomy outcomes performed on primary anterior teeth both with and without a citric acid solution to enhance smear layer removal.

METHODS

Patients with a matched pair of primary incisors (split-mouth design) with irreversible pulp changes were selected. A total of 36 teeth (18 children) received pulpectomies and were followed for 36 months. Pulpectomies were performed using sodium hypochlorite and saline solution as canal irrigants; during the last irrigation, the tooth was randomly selected to receive ( Group 1) or not receive (Group 2) the citric acid solution for smear layer removal. The roots were filled with ZOE paste.

RESULTS

Overall pulpectomy success was 90.6%. Cases with smear layer removal were successful 82.3% of the time; those without smear layer removal, 88.2%, and there were no statistical differences (P=1.00).

CONCLUSION

Pulpectomy with smear layer removal in primary incisors exhibited, after 36 months, a high success rate; however, comparable results were obtained when the smear layer was not removed.

Evolution of apical formation on immature necrotic permanent teeth

PURPOSE

To evaluate the evolution of apical formation on 28 necrotic immature permanent teeth treated with calcium hydroxide at different stages of root development.

METHODS

Apical formation in 28 necrotic incisors was carried out (27 upper and one lower incisors), in children between the ages of 6 and 13 years old (11 males, 10 females). Following anesthesia and rubber dam isolation, the chamber was opened and the coronal and root pulp tissue was removed. Next, after measuring the canal, the root canal was irrigated with 5% sodium hypochlorite. Once the canal was dried, it was filled with the CaOH2 powder mixed with physiologic saline solution to a dense consistency but malleable. This paste was compressed into the canal using a cotton pellet. The canal was completely filled up to the apex. Finally, the cavity opening was sealed with zinc oxide-eugenol (IRM) and glass-ionomer (Vitrebond). Follow-up appointments were made every 3 months in order to evaluate the evolution of the periapical radiolucency and the formation of the apical barrier.

RESULTS

The duration of the apical induction was 8.6 +/- 5.36 months. Increase or lack of growth in the length of the root canal and the type of root end closing was as follows: cementoid tissue (85.72%); osseous tissue (14.28%), with a 100% overall success rate. The evolution of these teeth was monitored over a 2-year period with re-infections occurring in 7.1 percent of the cases.

Comparison of the retentive strength of 3 different posts in restoring badly broken primary maxillary incisors

PURPOSE

The management of mutilated primary incisors in early childhood caries is a clinical challenge and necessitates the use of intraradicular retention. This study's purpose was to compare the retentive strength of 3 different types of posts in restoring broken primary incisors: (1) composite posts; (2) orthodontic "gamma" wire posts; and (3) glass fiber posts.

METHODS

This vitro study was performed on 30 extracted human primary maxillary incisors. Samples were randomly divided into 3 groups of 10 each: group 1 (composite posts and composite core); group 2 (orthodontic "gamma" wire posts and composite core); and group 3 (glass fiber posts and composite core). Mounted specimens were subjected for tensile strength on an Instron testing machine. The values were statistically analyzed.

RESULTS

Mean tensile strength values for glass fiber posts was 5.89+/-0.66 kg force, followed by 4.46+/-0.82 and 3.56+/-0.53 kg force for orthodontic wire posts and composite posts, respectively, with a statistically significant difference between and within the groups (P<.01). Groups 1 and 2 showed more bulk cohesive failure and less adhesive bond failure. Group 3 showed only adhesive bond failure.

CONCLUSION

Glass fiber posts showed greater dislodging strength, followed by orthodontic "gamma" wire posts and, least of all, composite posts.

[Effect of post space preparation on the sealability of root canal filled with 3 filling methods]

PURPOSE

To evaluate the effect of post space preparation on the sealability of canals filled with 3 filling methods.

METHODS

The crowns of 24 human anterior teeth extracted for periodontal disease were removed and the working length of canal was unified to be 16 mm. The teeth were divided into 3 groups at random: group A (normal temperature flow gutta-percha single-corn technique with GuttaFlow), group B (lateral compaction technique with AH Plus) and group C (warm vertical condensation technique with AH Plus+ BeeFill thermoplastics system). The root canals were prepared and filled according to different system. Microleakage of root canals of pre-post space preparation was measured with a fluid transport study one week after filling. Then the post space was prepared using 1#- 6# G drill step by step, by leaving 4 mm of root canal filling material apically. Microleakage of root canals of post-dowel space preparation was measured again. SPSS13.0 software package was used for statistical analysis.

RESULTS

No difference was found between pre-post space preparation and post-dowel space preparation in each experimental group (P>0.05). In pre-post space preparation, significant difference was found between group A and group B, group B and group C (P<0.05). In post-dowel space preparation, difference was found between group A and group B.Group A had the lowest microleakage (4.328+/-2.020)x10(-3)microl x kPa(-1) x min(-1).

CONCLUSIONS

The post space preparation do not effect the sealability of three root canal sealers. The sealability of canals filled with AH Plus are different when filled with different filling methods. Normal temperature flow gutta-percha single-corn technique with GuttaFlow gains the best sealability.

Cross-sectional assessment of apical dye penetration following three endodontic obturation techniques

This study sought to investigate apical leakage following three endodontic obturation techniques. Fifty-one recently extracted maxillary and mandibular canines were decoronated at the cementoenamel junction (CEJ) level and a size 10 file was passed to the exit of the apical foramen. Working distance was established 0.5 mm from where the file could be seen exiting the apical foramen. All teeth were instrumented using Brasseler Sequence files to a .06 taper size 40 file at working distance. The teeth were randomly divided into three groups: Group A (lateral condensation of gutta-percha with Roth's 811 Elite sealer), Group B (gutta-percha with GuttaFlow sealer), and Group C (Activ GP gutta-percha cone with Activ GP glass ionomer sealer). Two groups of three teeth served as positive and negative controls. There were no significant differences between Groups A and B; however, Group C was significantly different from Groups A and B.

In vitro sealing ability of temporary restorative materials used in endodontics

This study evaluated the marginal sealing ability of six temporary restorative materials. Seventy-six human premolars were extracted and divided into six groups (n = 12); the remaining four teeth were used as a control group. Coronal access and biomechanical preparation were performed and the root canals were sealed. The external dental surfaces were covered and the coronal access cavities were filled with one of the six materials. At that point, the teeth were immersed in 0.2% Rhodamine B solution for 72 hours and subjected to thermal cycling. Samples were rinsed in running water and sectioned longitudinally; at that point, the images of each tooth were digitized and marginal leakage was measured using the Image Tool program. Data were subjected to statistical analysis by ANOVA and Tukey's test for comparison between experimental groups. All of the glass ionomer cements tested, particularly Maxxion R, offered satisfactory sealing ability as temporary restorative materials.

[Prevention of endodontic interappointment emergencies after one-visit root canal therapy on deciduous teeth with METAPEX]

PURPOSE

To evaluate the clinical effect of calcium hydroxide-iodoform (METAPEX) in one-visit root canal therapy on deciduous teeth and the prevention of endodontic interappointment emergencies (EIAE).

METHODS

Two hundred and thirty-eight deciduous anterior and molar teeth from 178 patients were randomly divided into two groups treated with one-visit root canal therapy of METAPEX (experimental group) and zinc oxide eugenol paste (control group). The data was analyzed by Chi-square text with the SPSS14.0 software package.

RESULTS

The rate of EIAE after one-visit root canal therapy in the experimental group was significantly lower than in the control group (P<0.05).

CONCLUSION

The METAPEX could reduce the occurrence rate of EIAE in the one-visit root canal therapy on deciduous teeth.

Development of a basic root canal treatment (BRT) for primary oral health care--evaluation after one year

OBJECTIVES

Atraumatic Restorative Treatment (ART) was a major step forward in community dentistry but treatment options for deep carious lesions or pulp involvement still focus on tooth extraction in under-served areas worldwide. To bridge the gap between ART and extraction this pilot study aimed to develop and follow-up a basic root canal treatment for rural dental health facilities in the Republic of The Gambia (West Africa), faced with an environment lacking technical equipment and developing primary oral health care.

METHODS

25 single rooted teeth with acute irreversible pulpitis were root canal treated with a standardised endodontic instrument kit and a specific procedure. A step-back technique was used with intermittent chlorhexidine 0.2% and saline irrigation. Root canal obturation was performed using a single-cone technique with gutta-percha using Grossman's root canal cement. Coronal filling was carried out by using ART. Clinical examinations were documented before treatment, one day, five days, six months and twelve months postoperatively.

RESULTS

None of the root canal fillings had to be revised due to postoperative complications. In 9 out of 25 teeth, transitory apical pain disappeared after a few days. After six months, all ART fillings appeared clinically acceptable, two fillings had to be corrected. Four class II restorations and three class IV restorations needed replacement after 12 months. Patients' assessment of health related quality of life improved significantly, especially concerning dental pain, chewing ability and fitness for work.

CONCLUSIONS

Preliminary clinical follow-ups showed encouraging results for the basic root canal treatment approach. Longitudinal clinical studies with greater populations are required to substantiate these results. Modifications in the coronal filling technique are preferable to improve the clinical performance of extended ART cavity restorations.

A comparison of two methods of removing zinc oxide-eugenol provisional cement residue from the internal surface of cast restorations

AIM

Remnants of provisional cement on the internal surface of cast restorations can have an adverse effect on the performance of the definitive luting agent. The purpose of this study was to evaluate the effect of eugenol-containing temporary cement removal by an ultrasonic or an organic solvent on the retentive strength of metallic rings cemented to amalgam cores using zinc phosphate cement.

METHODS AND MATERIALS

A total of 36 cylindrical amalgam cores measuring 5.9 x 6 mm were made by condensing amalgam in brass molds for use in this in vitro study. Thirty-six cylindrical spaces measuring 6 x 6 mm were machined in the center of cast rods of Rexillium III alloy to create simulated retainers. The amalgam cores were divided into two groups and provisionally cemented in these cylindrical spaces (retainers) using zinc oxide-eugenol cement. After separation of the cores from the retainers, one group was cleaned with an ultrasonic cleaning device with water and the other group was cleaned with Solitine organic solvent. All specimens were then cemented with zinc phosphate cement and the samples were stored at 100% humidity in a 37 degrees C water bath after which they were tested with a DARTEK testing machine at a 0.02 cm/minute cross head speed. The data were analyzed using the Independent t-test.

RESULTS

The statistical analysis revealed a significant difference between the two groups (p<0.0005) with the ultrasonic group having significantly higher separation forces than the Solitine group.

CONCLUSION

Specimens treated with the ultrasonic cleaner showed a higher mean separation force (282.2 MPa) than the solvent group (439.5 MPa).

CLINICAL SIGNIFICANCE

Despite the convenience of using an organic solvent for cleaning the internal surface of cast restorations, the ultrasonic cleaning method is more effective for removing zinc-oxide temporary cement.

[Comparison of two means for evaluation of apical microleakage]

PURPOSE

To compare the consistency of two means of evaluating the apical microleakage.

METHODS

Forty-nine extracted single-rooted human teeth were divided into 3 experimental groups of 15 teeth each, in addition to a positive and negative control group of 2 teeth each. The teeth were instrumented, then obturated using lateral condensation and one of three endodontic sealers: AH Plus(group A), Cortisomol(group B) and zinc oxide eugenol(group C). The apical microleakage was measured by transparent tooth technique or dye dissolution each. SPSS 12.0 software package was used for One-way ANOVA and Kruslal-Wallis test.

RESULTS

The two methods both showed that the microleakage in group A was significantly less (P<0.05) than that in group B and C. There was no significant difference between group B and C(P>0.05).

CONCLUSION

Based on the dye penetration method, there is some consistency between the transparent tooth technique and dye dissolution method for evaluating apical microleakage.

[Comparative study on dogs between CO2 laser and conventional technique in direct pulp capping]

Three dogs have been used in this experiment. Class V cavities were made in sixty teeth. A pulpal communication was provoked intentionally in these cavities. Teeth were randomly split in 2 groups (30 teeth for each). On first group, the pulp bleeding was stopped until appearance of coagulum on exposed pulp surfaces by means of CO2 laser irradiation (Output Power: 3 W, Pulse duration: 0.1 sec, frequency: 1 Hz, spot size diameter: 0.3 mm, Energy density: 425 J/cm2). Calcium Dihydroxide was deposited followed by a temporary filling (IRM, Dentsply, De Trey, Germany). In the second group, the calcium Dihydroxide was deposited directly on exposed bleed pulp (conventional technique) followed by the same temporary filling. Ten weeks later, all teeth were extracted and prepared for histological study.

RESULTS

93% of treated teeth preserved their pulp vitality in the group treated with CO2 laser for direct pulp capping versus 82% in the group treated by conventional technique. The average of the thickness of the dentinal bridge newly formed was 391.5 +/- 33 microm for teeth irradiated with laser and 294.1 +/- 28 microm for teeth treated by conventional technique. The thickness of the dentinal bridge newly formed in teeth treated by means of CO2 laser was 33% more important than in those treated by the conventional technique. Statistical analysis showed a significant difference between the averages of values in all groups (p < 0.05). To conclude, CO2 Laser use in the direct pulp capping increases significantly the percentage of pulp vitality preservation and the thickness of the dentinal bridge newly formed after pulp exposition.

Evaluation of 2 endodontic techniques used to treat human primary molars with furcation radiolucency area: A 48-month radiographic study

OBJECTIVE

To evaluate 2 techniques for the treatment of human primary molars with necrotic pulp and bifurcation bone loss by means of radiographic examination for 48 months.

METHOD AND MATERIALS

Fifty-one mandibular primary molars were evaluated in children ranging from 4.5 to 6.5 years of age. The teeth with necrotic pulp and bifurcation bone loss were diagnosed by radiographic examination. The teeth were divided into 2 groups: group 1 (28 teeth) -- pulpotomy technique using formocresol as a temporary dressing between sessions and coronal chamber obturation with zinc oxide-eugenol cement; and group 2 (23 teeth) -- pulpectomy technique with calcium hydroxide paste as a temporary dressing between sessions and root canal obturation with a dense calcium hydroxide paste. Standardized radiographs were taken immediately after the fillings were completed and after 12, 24, 36, and 48 months. The radiographs were digitized and analyzed with software that outlined and measured the bifurcation radiolucency.

RESULTS

Bifurcation radiolucency reduced significantly or repaired completely for both treatments in the first 12 months. Minor radiographic reduction of the lesion was observed from 12 to 24 months, and no significant reduction of the remaining radiolucent area was observed from 24 to 48 months after treatment.

CONCLUSION

The 2 endodontic techniques evaluated showed similar results. The main effect of treatment on the lesion repair was obtained in the first year after treatment.

[Effect of different treatments of dentin surface on sheer bond strength between different bonding agents and dentin]

OBJECTIVE

To evaluate the effect of Zinc oxide-eugenol cement and Gluma desensitizer on the sheer bond strength of three kinds of dentin bonding agents. The three dentin bonding agents were Zinc phosphate cement, Glass ionomer cement and Super-Bond C&B. To find the theory depending for the using of different protective methods and the selecting of different kinds of dentin bonding agents in prepared abutment teeth.

METHODS

The buccal surfaces of ninety freshly extracted human premolars were flattened to expose an adequate area of lower dentin. Followed by wet-grinding on a series of silicon carbide paper from number 320, 400, 600 grit to produce the dentin bonding surface. The teeth roots were embedded in self-curing resin with the crown out of the resin. The embedded ninety teeth were divided randomly into three groups. The group A was control and the dentin surfaces were not treated. The group B was covered with a paste of Zinc oxide-eugenol cement. The group C was covered with Gluma desensitizer. Calculating the sheer strength between three bonding agents and dentin after the two treatments of dentin surface. The results were statistically assessed with SPSS software. Dentin surfaces were observed with scanning electron microscope (SEM).

RESULTS

The sheer bond strengths of Zinc phosphate cement had significant decrease (P<0.05), especially the C1 group. The sheer bond strengths of Glass ionomer cement and Super-Bond C&B had no significant difference.

CONCLUSION

Zinc oxide-eugenol cement and Gluma desensitizer could reduce the sheer bond strength of Zinc phosphate cement with dentin surface. Zinc oxide-eugenol cement and the Gluma desensitizer could not effect Glass ionomer cement and the Super-Bond C&B with dentin.

[Investigation of influence on apical sealability generated by root canal sealer placement]

OBJECTIVE

To investigate the influence of sealer placement on apical sealability in root canal treatment.

METHODS

100 extracted single root canal teeth were selected. All canals were prepared by manual Protaper instrument in a step-back way. The samples were divided into 5 groups randomly. A group: 30 samples, sealer placement by chief gutta percha; B group: 30 samples, sealer placement by K file; C group: 30 samples, sealer placement by spreader; D group: 5 samples, a positive control; E group: 5 samples, a negative control. There were 2 subsets in each experimental group which were obturated by lateral gutta percha with or without sealer. Glucose oxidase method was used to measure the apical leakage at the 1st 2nd, 4th, 7th, 10th, 15th, 20th, 25th, 30th day of the experiment.

RESULTS

Apical sealability varied with different sealer placement methods (F=4.832, P=0.001). Sealer placement by chief gutta percha (A group) had the best instant apical sealability. However, lateral gutta percha with or without sealer didn't affect the apical sealibility.

CONCLUSION

Placing the same kind sealer in different ways can affect the apical sealability. There were no significant differences of the apical leakage no matter the lateral gutta percha with or without sealer. In order to get better instant apical sealability and simplify the clinic operation, placing the sealer with a chief gutta percha while the lateral gutta percha without sealer is recommended.

Metaanalysis of filler materials in periapical surgery

OBJECTIVE

To evaluate the success and failure, apical sealing and biocompatibility of silver amalgam, IRM, SuperEBA and MTA as retrograde filler materials.

STUDY DESIGN

A metaanalysis is made of filler materials in periapical surgery, evaluating a total of 30 articles published in recent years.

RESULTS

Percentage success with silver amalgam was 76.5% and slightly inferior to that afforded by IRM. Performance in turn increased considerably when the materials used were SuperEBA or MTA. As regards marginal leakage, MTA with a mean leakage time of 65.5 days afforded the best results, followed by SuperEBA, IRM and silver amalgam. MTA was the most biocompatible of the materials studied, with practically no inflammatory response, while inflammation proved mild or moderate with SuperEBA, mild with IRM, and moderate to severe in the case of silver amalgam. Tissue regeneration was only observed with MTA, in the same way as cement appositioning. Bone neoformation was observed with all four filler materials.

CONCLUSIONS

MTA appears to be an ideal material, though the results obtained require confirmation by in vivo studies.