Cyclic Fatigue Resistance of Rotary versus Reciprocating Endodontic Files: A Systematic Review and Meta-Analysis

(1) Background: The failure of nickel-titanium (NiTi) rotary files is a complication related to endodontic instruments. The aim of this study was to compare the resistance to cyclic fatigue between rotary and reciprocating file systems. (2) Methods: Specific PICO: Population (P): artificial root canals; Interventions (I): instrumentation with NiTi rotary and reciprocating files; Comparison (C): rotary versus reciprocating files; Outcome (O): cyclic fatigue resistance. Studies were identified through bibliographic research using electronic databases (Medline, Embase, Scopus, SciELO, and WOS). The studies were combined using a random effects model by the inverse variance method. The effect size was the mean of the time to fracture (TTF) and number of cycles to fracture (NCF). Heterogeneity was assessed using the p value of the Q test for heterogeneity and the I2. (3) Results: TTF for rotary files was determined in 474.5 s and 839.1 for reciprocating without statistically significant differences. NCF for rotary systems was determined in 1444.2 and for reciprocating file systems in 4155.9 with statistically significant differences (p = 0.035), making reciprocating files more resistant. (4) Conclusions: Reciprocating files have better resistance to cyclic fatigue than rotary files. When tested in double curvature canals, reciprocating files also showed higher resistance.

Treatment of Esthetic Complications with Peri-implant Soft Tissue: A Description of the "Apical Approach" Surgical Technique and Presentation of Two Clinical Cases

Peri-implant soft tissue deformities are an increasingly common phenomenon in the esthetic zone. While the most widely studied esthetic complications are peri-implant soft tissue dehiscences, there are other esthetic concerns in routine clinical practice that require investigation and treatment. Thus, this report on two clinical cases describes a surgical approach using the apical access technique to treat peri-implant soft tissue discoloration and fenestration. In both clinical scenarios, the defect was accessed via a single horizontal apical incision without removing the cement-retained crowns. A bilaminar technique using apical access with a simultaneous connective tissue graft seems to offer promising results for the treatment of peri-implant soft tissue deformities. At the 12-month reevaluation, an increase in peri-implant soft tissue thickness was observed, resolving the pathologies presented.

A Comparative Analysis of the Piezoelectric Ultrasonic Appliance and Trephine Bur for Apical Location: An In Vitro Study

To compare and contrast the accuracy of piezoelectric ultrasonic insert (PUI) and trephine bur (TB) osteotomy site preparation techniques for apical location. (1) Material and methods: A total of 138 osteotomy site preparations were randomly distributed into one of two study groups. Group A: TB technique (n = 69) and B: PUI technique (n = 69). A preoperative cone-beam computed tomography scan and an intraoral scan were performed and uploaded to implant-planning software to plan the virtual osteotomy site preparations for apical location. Subsequently, the osteotomy site preparations were performed in the experimental models with both osteotomy site preparation techniques and a postoperative CBCT scan was performed and uploaded into the implant-planning software and matched with the virtually planned osteotomy site preparations to measure the deviation angle and horizontal deviation as captured at the coronal entry point and apical end-point between osteotomy site preparations using Student’s t-test statistical analysis. (2) Results: The paired t-test found statistically significant differences at the coronal entry-point deviations (p = 0.0104) and apical end-point deviations (p = 0.0104) between the TB and PUI study groups; however, no statistically significant differences were found in the angular deviations (p = 0.309) between the trephine bur and piezoelectric ultrasonic insert study groups. (3) Conclusions: The results showed that the TB is more accurate than the PUI for apical location.

Adding Two Antimicrobial Glasses to an Endodontic Sealer to Prevent Bacterial Root Canal Reinfection: An In Vivo Pilot Study in Dogs

Current endodontic procedures continue to be unsuccessful for completely removing pathogens present inside the root canal system, which can lead to recurrent infections. In this study, we aimed to assess the antimicrobial capacity and tissue response of two inorganic bactericidal additives incorporated into a paste root canal sealer on contaminated root dentin in vivo. An experimental study was performed in 30 teeth of five Beagle dogs. After inducing microbiological contamination, root canal systems were treated by randomly incorporating one of two antimicrobial additives into a commercial epoxy-amine resin sealer (AH Plus), i.e., G3T glass-ceramic (n = 10) and ZnO-enriched glass (n = 10); 10 samples were randomized as a control group. After having sacrificed the animals, microbiological, radiological, and histological analyses were performed, which were complemented with an in vitro bactericidal test and characterization by field emission scanning electron microscopy. The tested groups demonstrated a non-significant microbiological reduction in the postmortem periapical index values between the control group and the bactericidal glass-ceramic group (p = 0.885), and between the control group and the ZnO-enriched glass group (p = 0.169). The histological results showed low values of inflammatory infiltrate, and a healing pattern characterized by fibrosis in 44.4% of the G3T glass-ceramic and 60.0% of ZnO-enriched glass. Bactericidal glassy additives incorporated in this root canal sealer are safe and effective in bacterial reduction.

A Comparative Study of Biocompatibility in Rat Connective Tissue of a New Mineral Trioxide Compound (Theracal) versus MTA and a Bioactive G3 Glass

The aim of this paper was to assess the differences in tissue response to implantation during 15, 30 and 45 days in the subcutaneous connective tissue of Wistar rats from three biomaterials: Angelus MTA^®, Theracal LC^®, and Angelus MTA^® to which 25% bioglass G3 was added. Twenty-four Wistar rats were used, the materials were inserted into the rat’s dorsal area in silicone tubes 5 mm long by 1.5 mm diameter. Histological reaction was assessed at 15, 30, and 45 days after implantation. They were then stained with hematoxylin eosin and evaluated by two observers. Data were analyzed using Fisher’s exact test and Mann–Whitney’s U test was used to determine the association between variables. Angelus MTA induced the formation of dystrophic calcifications twice as much as Theracal LC (p < 0.05). The addition of G3 did not affect the greater or lesser occurrence of calcifications (p > 0.05). Theracal LC and MTA plus G3 caused an inflammatory reaction, which was chronic at 15 days and decreased in intensity, almost disappearing after 45 days. Theracal LC, as well as Angelus MTA plus G3, were well tolerated when implanted in the subcutaneous connective tissue of rat. Histologically, no inconvenience was found for the use by direct contact of Theracal LC, and the mixture of MTA with 25% bioactive glass G3, in the tissue of Wistar rats.

Influence of the type of reciprocating motion on the cyclic fatigue resistance of reciprocating files in a dynamic model

Background

The aim of this study was to compare the influence of two novel reciprocating movements on the cyclic fatigue resistance of endodontic reciprocating files.

Methods

30 Procodile® (Komet Medical, Lemgo, Germany) files were selected in this study and distributed according to the following study groups depending on the movements to be performed: ReFlex Dynamic (n = 10), ReFlex Smart (n = 10) and Reciproc (n = 10) reciprocating movement. These files were fixed to a specific dynamic cyclic fatigue device designed and manufactured by 3D impression to simulate the pecking motion performed by the operator. The time to failure and the number of cycles of in-and-out of the endodontic files was registered. The results were analyzed by ANOVA and Weibull statistics.

Results

Statistically significant differences were found when the number of cycles of in-and-out movement and the time to failure of ReFlex Dynamic and Reciproc reciprocating movement (p < 0.001) and between ReFlex Smart and Reciproc reciprocating movement (p < 0.001) were compared in pairs. However, no statistically significant differences were observed between time to failure and number of cycles of in-and-out movement of ReFlex Dynamic and ReFlex Smart reciprocating movement (p = 0.253).

Conclusions

The ReFlex Smart reciprocating movement increased the cyclic fatigue resistance of endodontic reciprocating files compared with traditional reciprocating movement.

Efficacy of Computer-Aided Static Navigation Technique on the Accuracy of Endodontic Microsurgery. A Systematic Review and Meta-Analysis

The aim of this systematic review and meta-analysis was to analyze the efficacy of the computer-aided static navigation technique on the accuracy of root apex location in endodontic microsurgery.

MATERIAL AND METHODS

A systematic literature review and meta-analysis, based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations, of clinical studies that evaluated the apex location rate of the computer-aided static navigation techniques applied to endodontic microsurgery. A total of four databases were consulted in the literature search: Pubmed-Medline, Scopus, Cochrane, and Web of Science. After eliminating duplicated articles and applying the inclusion criteria, seven articles were selected for the qualitative and the quantitative analysis.

RESULTS

The root apex location success rate stated at 96.8% (confidence interval (CI): 93.0-100%) of the cases performed through a computer-aided static navigation technique. The prediction interval ranges from 91.4% to 100%. The meta-analysis did not detect heterogeneity between the combined studies (Q-test = 6.15; p-value = 0.407; I2 = 2.4%). The computer-aided static navigation techniques showed a root apex location success rate 27 times higher than conventional endodontic microsurgery procedures (Q test = 0.80; p = 0.671; I2 = 0%). Three studies of computer-aided static navigation techniques and control group were compared using a random effects model with the Mantel-Haenszel method with a statistically significant odds success ratio of 27.7, with a 95% confidence interval between 11.3 and 68.1 (z test = 7.23; p < 0.0001).

CONCLUSIONS

According to in vitro studies analyzed, endodontic microsurgeries performed through computer-aided static navigation techniques show a high precision.

Technology at the service of surgery in a new technique of autotransplantation by guided surgery: a case report

Background

The aim of this case report was to use a surgical technique for autotransplantation of tooth using virtually planned 3D printed surgical templates for guided osteotomy preparation of the recipient of donor tooth.

Case presentation

An 18-year-old male patient received autotransplantation of the right mandibular third molar to replace an included right second molar. This procedure was based on guided implant surgery methods by superimposition of DICOM files and 3D data sets of the jaws. In order to design a 3D-printed template with the aid of a fully digital workflow; the third molar was conserved in PRGF during the surgical procedure and the tooth socket was prepared with a template and the help of a 3D-printed donor tooth copy in order to prevent iatrogenic damage to the donor tooth. This template and replica were manufactured using 3D-printing techniques. The transplanted tooth was placed in infra-occlusion and fixed with a suture splint and root canal therapy was performed 15 days later. The intervention was be accomplished by performing preplanned virtual transplantations with guided osteotomies to ensure accurate donor tooth placement in the new recipient site. The 24 months follow-up showed physiological clinical and radiologic results compatible with healing periradicular tissues.

Conclusions

This approach enables the planning and production of a 3D printed surgical template using the latest diagnostic methods and techniques of guided implant surgery. These accurate virtually predesigned surgical templates and printed analogues of the donor tooth could facilitate autotransplantation, ensuring an atraumatic surgical protocol.

Photodynamic therapy in endodontic root canal treatment significantly increases bacterial clearance, preventing apical periodontitis

OBJECTIVE

To analyze the antimicrobial activity of photodynamic therapy as an adjunct to conventional endodontic treatment, particularly against Enterococcus faecalis.

METHOD AND MATERIALS

A total of 42 single-rooted teeth obtained from 33 patients with apical periodontitis were included. Sampling was developed in three stages: (1) immediately after accessing the root canal, (2) after chemical and mechanical instrumentation, and finally, (3) after photodynamic therapy application. The bacterial load of each sample was quantified by seeding on blood agar plates and selective M-Enterococcus agar. All growing colonies were identified using MALDI-TOF (Bruker; matrix-assisted laser desorption/ionization time-of-flight), and the entire bacterial microbiota composition was determined in the first sample by PCR-DGGE (polymerase chain reaction denaturing gradient gel electrophoresis), using 16 rDNA primers and selective nucleotide sequencing.

RESULTS

The endodontic therapy obtained a mean reduction in the cultivable bacterial load of 1.12 log, whereas the photodynamic therapy combination significantly increased the bacterial clearance (P < .0001). Viable cells of E faecalis were detected in 16.6% of root canals, with a mean value of 93 CFU per tooth, which was reduced to 67 and 9 CFU/tooth after conventional endodontic and photodynamic therapy treatments, respectively. Molecular E faecalis detection demonstrated that this species was present in 23.2% of baseline samples. DGGE analysis demonstrated the existence of a more complex microbiota than those observed using classical cultures.

CONCLUSION

Photodynamic therapy as an adjunct to root canal treatment produces a significant reduction in E faecalis bacterial load, and it should be considered in the prevention of apical periodontitis.

Endodontic re-treatment and restorative treatment of a dens invaginatus type II through new technologies

Background

The complex anatomy of dens invaginatus makes access cavity to root canal system difficult, which has an impact on the prognosis of these teeth. A novel technique, based on new technologies, is proposed to make access cavity conservative and guided with minimal dental structure lost.

Material and Methods

This case report shows the root canal retreatment and the endodontic surgery of a dens invaginatus type II in a left lateral upper incisor previously treated which was affected by a chronic apical abscess and an apical fracture. A Cone Beam Computed Tomography was performed to better diagnosis the dental anatomy. An intraoral scan was performed to get a digital 3D model. A computer-guided implant planning software was used to plan the access cavity and design the splint guided. Finally, the clinical crown was restored by a resin nanoceramic veneer made by a chairside system made up of an intraoral scanning unit and a grinding unit. Last, the authors carried through the endodontic surgery to extract the apical fractured fragment.

Results

Follow-up appointments at 6, 12 and 18 months showed a radiographic reduction of the periapical lesion and absence of clinical signs.

Conclusions

The splint guide allowed a guided and conservative access cavity to root canal system. It facilitates the root canal retreatment and improves the prognosis of the teeth with dental malformations.

Key words:CAD-CAM, Cone-Beam Computed Tomography, dens in dente, dens invaginatus, dental pulp cavity, endodontics.

An analysis in vivo of intracanal bacterial load before and after chemo-mechanical preparation: A comparative analysis of two irrigants and two activation techniques

Background

The goals of this randomized double-blind trial were to assess the antimicrobial activity in vivo of Sodium hypochlorite (NaOCl) vs. chlorhexidine gluconate (CHX) used in combination either with EndoActivator® or IRRI S® files in patients with apical periodontitis.

Material and Methods

A total of 120 patients with apical periodontitis (in single or multiple root canals) were randomly assigned to the four irrigation protocols outlined below: Group A: 5.25% sodium hypochlorite (NaOCl) + EndoActivator®; Group B: 5.25% NaOCl + IRRI S® files; Group C: 2% chlorhexidine gluconate (CHX) + EndoActivator®; Group D: 2% CHX + IRRI S® files. Paper points were used to collect microbiological samples before (1A samples) and after (1B samples) irrigation. Viable colony-forming units (CFU) were quantified twice: (1) without speciation, and (2) only for Enterococcus Faecalis(EF). Statistical analysis was performed using SPSS 22.0 for Windows.

Results

No significant differences were observed between NaOCl and CHX in the reduction of CFU; in fact, reduction was < 93% for the two irrigants. Conversely, statistically significant differences were found between the two activation techniques (sonic and ultrasonic) in the reduction of Enterococcus Faecalis(EF). Thus, the effectiveness of ultrasonic activation was significantly higher (< 93%; p=0.012) as compared to sonic activation. Following the combination of the two irrigants with the two activation techniques (groups A, B, C and D), significant differences were observed between group A and B (p=0.025) in the reduction of EF populations, reaching up to 94%.

Conclusions

NaClO and CHX are effective in reducing intracanal bacterial load. Ultrasonic activation is the most effective activation technique in reducing EF populations.

Key words:Chlorhexidine gluconate, sodium hypochlorite, ultrasonic irrigation, sonic irrigation, apical periodontitis, Enterococcus faecalis.