A quantitative analysis of rotary, ultrasonic and manual techniques to treat proximally flattened root canals

Effect of passive ultrasonic agitation during final irrigation on cleaning capacity of hybrid instrumentation

OBJECTIVES

To evaluate the effect of passive ultrasonic agitation on the cleaning capacity of a hybrid instrumentation technique.

MATERIALS AND METHODS

Twenty mandibular incisors with mesiodistal-flattened root shape had their crowns sectioned at 1 mm from the cementoenamel junction. Instrumentation was initiated by catheterization with K-type files (Denstply Maillefer) #10, #15, and #20 at 3 mm from the working length. Cervical preparation was performed with Largo bur #1 (Dentsply Maillefer) followed by apical instrumentation with K-type files #15, #20 and #25, and finishing with ProTaper F2 file (Denstply Maillefer). All files were used up to the working length under irrigation with 1 mL of 2.5% sodium hypochlorite (Biodynâmica) at each instrument change. At the end of instrumentation, the roots were randomly separated into 2 groups (n = 10). All specimens received final irrigation with 1 mL of 2.5% sodium hypochlorite. The solution remained in the root canals in Group 1 for one minute; and ultrasonic agitation was performed in Group 2 for one minute using a straight tip inserted at 1 mm from working length. The specimens were processed histologically and the sections were analyzed under optic microscope (×64) to quantify debris present in the root canal.

RESULTS

The samples submitted to ultrasonic agitation (Group 2) presented significant decrease in the amount of debris in comparison with those of Group 1 (p < 0.05).

CONCLUSIONS

The hybrid instrumentation technique associated with passive ultrasonic agitation promoted greater debris removal in the apical third of the root canals.

Evaluation of marginal leakage of different temporary restorative materials in Endodontics

Aim:

The aim of this study is to assess the coronal marginal leakage of three temporary restorative materials used for root canal sealing after endodontic treatment.

Materials and Methods:

A total of 88 single-rooted teeth were submitted to biomechanical preparation and filled by lateral condensation technique. After obturation process, the teeth were randomly separated into four groups, being two teeth of each group used as positive and negative control. Temporary sealing was performed as follows: GI - Clip F (VOCO); GII - Bioplic (Biodinβmica); GIII - Vitremer (3M ESPE) and GIV - Ketak N100 (3M ESPE). Next, the specimens were immersed into Indian ink for 30 and 60- days, being 10 specimens for each time interval and then submitted to diaphanization to verify the amount of coronal leakage using a measuring microscope.

Results:

Leakage mean values within the 30-day period were as follows: Vitremer (0.3 mm), Ketak N100 and Clip F (0.6 mm) and Bioplic (1.7 mm). Within the 60-day period, leakage means were 1.1 mm, 1.5 mm, 2.2 mm and 2.6 mm, respectively.

Conclusions:

None of the materials was capable of preventing marginal leakage within the 30- and 60-day period. In both time intervals, Bioplic presented the highest mean of leakage and Vitremer the lowest.

Performance of RaCe Instrumentation System in Curved Root Canals: A Comprehensive Analysis by Three Study Methods

In this study, curved maxillary molar root canals were instrumented with RaCe rotary system to evaluate: 1. the occurrence of canal transportation using a radiographic platform; 2. the action of the instruments on the dentin walls, centering ability and canal enlargement by analysis of digital images; and the percentage of regular dentin surfaces and debris within the canal by histological analysis. Ten mesiobuccal roots of extracted human maxillary molars were embedded in acrylic resin and sectioned at the middle and apical thirds. Root canal shaping was performed using the RaCe rotary system at 250 rpm and 1 Ncm torque. Each instrument set was used five times according to a crown-down technique in the following sequence: 40/0.10, 35/0.08, 25/0.06, 25/0.04, 25/0.02 (working length - WL), 30/0.02 (WL) and 35/0.02 (WL). Each instrument was inserted until resistance was felt and then pulled back, followed by brushing movements towards all canal walls. Each specimen was assessed by three study methods: radiographic platform, digitized image assessment and histological analysis. The radiographic platform showed lack of apical transportation. No statistically significant difference (Wilcoxon test, p>0.05) was found between the middle and apical thirds regarding instrument action on dentin walls, centering ability, area of root canal enlargement, percentage of regular dentin surfaces and debris within the root canal. It may be concluded that RaCe system is a suitable method for the preparation of curved root canals, regarding the maintenance of root canal original path, action on dentin walls, canal enlargement and removal of debris from the root canal lumen.

Cleaning capacity promoted by motor-driven or manual instrumentation using ProTaper Universal system: Histological analysis

Aim:

The aim of this study was to assess the cleaning capacity of the Protaper system using motor-driven or manual instrumentation.

Materials and Methods:

Ten mandibular molars were randomly separated into 2 groups (n = 5) according to the type of instrumentation performed, as follows: Group 1 - instrumentation with rotary nickel-titanium (Ni-Ti) files using ProTaper Universal System (Dentsply/Maillefer); and, Group 2 - instrumentation with Ni-Ti hand files using ProTaper Universal (Dentsply-Maillefer). Afterwards, the teeth were sectioned transversely and submitted to histotechnical processing to obtain histological sections for microscopic evaluation. The images were analyzed by the Corel Photo-Paint X5 program (Corel Corporation) using an integration grid superimposed on the image.

Results:

Statistical analysis (U-Mann-Whitney - P < 0.05) demonstrated that G1 presented higher cleaning capacity when compared to G2.

Conclusions:

The rotary technique presented better cleaning results in the apical third of the root canal system when compared to the manual technique.

Morphometrical analysis of cleaning capacity of a hybrid instrumentation in mesial flattened root canals

The cleaning capacity of hybrid and rotary instrumentation techniques in mesial flattened canals of mandibular first molars was evaluated by morphometrical analysis in this study. Twenty human mandibular first molars were randomly assigned into two groups, according to instrumentation technique, as follows: group 1, instrumentation with ProTaper Starter Kit (Dentsply/Maillefer) rotary system; group 2, manual instrumentation using K files (Dentsply/Maillefer) by crown-down technique in middle and apical thirds, cervical preparation with Gates-Glidden #1 and #2 (Dentsply/Maillefer) burs, and to finalise the preparation, ProTaper F2 and F3 rotary files. Serial transverse cross-sections (5 µm) of the apical third, stained with hematoxylin and eosin, were analysed at 100× original magnification. The images were submitted to morphometrical analysis with an integration grid to determine the percentage of root canal area with debris. Statiscal analysis (t-Student, P < 0.05) showed significant difference between the techniques (P < 0.05), although neither completely cleaned the root canal.

Assessment of canal walls after biomechanical preparation of root canals instrumented with Protaper Universal rotary system

Objective:

The aim of this study was to examine the instrumented walls of root canals prepared with the ProTaper Universal™ rotary system.

Material and Methods:

Twenty mesiobuccal canals of human first mandibular molars were divided into 2 groups of 10 specimens each and embedded in a muffle system. The root canals were transversely sectioned 3 mm short of the apex before preparation and remounted in their molds. All root canals were prepared with ProTaper Universal™ rotary system or with Nitiflex™ files. The pre and postoperative images of the apical thirds viewed with a stereoscopic magnifier (×45) were captured digitally for further analysis. Data were analyzed statistically by Fisher's exact test and Chi-square test at 5% significance level.

Results:

The differences observed between the instrumented and the noninstrumented walls were not statistically significant (p<0.05).

Conclusions:

The Nitiflex™ files and the ProTaper Universal™ rotary system failed to instrument all the root canal walls.