Clinical Implications and Microbiology of Bacterial Persistence after Treatment Procedures

Ultrasonic irrigation of the root canal can be performed with or without simultaneous ultrasonic instrumentation. When canal shaping is not undertaken the term passive ultrasonic irrigation (PUI) can be used to describe the technique. In this paper the relevant literature on PUI is reviewed from a MEDLINE database search. Passive ultrasonic irrigation can be performed with a small file or smooth wire (size 10-20) oscillating freely in the root canal to induce powerful acoustic microstreaming. PUI can be an important supplement for cleaning the root canal system and, compared with traditional syringe irrigation, it removes more organic tissue, planktonic bacteria and dentine debris from the root canal. PUI is more efficient in cleaning canals than ultrasonic irrigation with simultaneous ultrasonic instrumentation. PUI can be effective in curved canals and a smooth wire can be as effective as a cutting K-file. The taper and the diameter of the root canal were found to be important parameters in determining the efficacies of dentine debris removal. Irrigation with sodium hypochlorite is more effective than with water and ultrasonic irrigation is more effective than sonic irrigation in the removal of dentine debris from the root canal. The role of cavitation during PUI remains inconclusive. No detailed information is available on the influence of the irrigation time, the volume of the irrigant, the penetration depth of the instrument and the shape and material properties of the instrument. The influence of irrigation frequency and intensity on the streaming pattern as well as the complicated interaction of acoustic streaming with the adherent biofilm needs to be clarified to reveal the underlying physical mechanisms of PUI.

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Passive ultrasonic irrigation of the root canal: a review of the literature.

Ng Y-L, Mann V, Gulabivala K. A prospective study of the factors affecting outcomes of nonsurgical root canal treatment: part 1: periapical health. International Endodontic Journal. Aim To investigate the probability of and factors influencing periapical status of teeth following primary (1! RCTx) or secondary (2! RCTx) root canal treatment. Methodology This prospective study involved annual clinical and radiographic follow-up of 1! RCTx (1170 roots, 702 teeth and 534 patients) or 2! RCTx (1314 roots, 750 teeth and 559 patients) carried out by Endodontic postgraduate students for 2‐4 (50%) years. Pre-, intra- and postoperative data were collected prospectively on customized forms. The proportion of roots with complete periapical healing was estimated, and prognostic factors were investigated using multiple logistic regression models. Clustering effects within patients were adjusted in all models using robust standard error. Results The proportion of roots with complete periapical healing after 1! RCTx (83%; 95% CI: 81%, 85%) or 2! RCTx (80%; 95% CI: 78%, 82%) were similar. Eleven prognostic factors were identified. The conditions that were found to improve periapical healing significantly were: the preoperative absence of a periapical lesion (P = 0.003); in presence of a periapical lesion, the smaller its size (P £ 0.001), the better the treatment prognosis; the absence of a preoperative sinus tract (P = 0.001); achievement of patency at the canal terminus (P = 0.001); extension of canal cleaning as close as possible to its apical terminus (P = 0.001); the use of ethylene-diaminetetra-acetic acid (EDTA) solution as a penultimate wash followed by final rinse with NaOCl solution in 2! RCTx cases (P = 0.002); abstaining from using 2% chlorexidine as an adjunct irrigant to NaOCl solution (P = 0.01); absence of tooth/root perforation (P = 0.06); absence of interappointment flare-up (pain or swelling) (P = 0.002); absence of root-filling extrusion (P £ 0.001); and presence of a satisfactory coronal restoration (P £ 0.001). Conclusions Success based on periapical health associated with roots following 1! RCTx (83%) or 2! RCTx (80%) was similar, with 10 factors having a common effect on both, whilst the 11th factor ‘EDTA as an additional irrigant’ had different effects on the two treatments.

https://www.endoexperience.com/documents/Aprospectivestudyofthefactorsaffectingoutcomesofnonsurgicalrootcanaltreatment-part1-periapic.pdf

A prospective study of the factors affecting outcomes of nonsurgical root canal treatment: part 1: periapical health.

Review of contemporary irrigant agitation techniques and devices

A scanning electron microscopic evaluation of four root canal irrigation regimens

Ceramic dental biomaterials and CAD/CAM technology: state of the art.

Mechanical effectiveness of root canal irrigation

Statement of problem. Acrylic resin complete dentures exhibit certain unavoidable dimensional changes. Processing shrinkage and expansion due to water uptake are 2 important aspects influencing dimensional accuracy. Purpose. This study investigated linear dimensional changes and water sorption of dentures processed by dry and wet heat with different rates of cooling. Methods. Fine crosses marked on tinfoil inserts were placed at the incisive papilla and tuberosity regions of edentulous maxillary casts and incorporated into the dentures during polymerization by 3 processing techniques. A traveling microscope was used to measure the distances between the reference points to determine dimensional changes. Water uptake and content were determined by the mass changes of the dentures with an electronic balance. Data of linear dimensional change and water sorption were analyzed by multivariate analysis of variance and analysis of variance, respectively. Bonferroni simultaneous confidence intervals (95%) were applied for multiple comparison. Results. Dry heat–processed and water bath–processed acrylic resin dentures did not exhibit significant differences in shrinkage (0.42% to 0.58%) at water saturation. Amounts of water sorption of dentures processed by dry and wet heat (0.50 and 0.48 mass%, respectively) were not significantly different, and their associated expansion did not entirely compensate for the processing shrinkage. The initial water content of dry heat–processed dentures (1.77 mass%) was unexpectedly slightly higher than that of wet heat–processed dentures (1.68 mass%). The rate at which the dentures cooled did not affect their initial water content and subsequent water uptake. Conclusions. Water uptake of dry and wet heat–processed acrylic resin dentures after deflasking was in both cases low, and the dentures did not reveal significant differences in shrinkage at water saturation. Air oven–processed and water bath–processed acrylic resin dentures show similar dimensional shrinkage at water saturation. (J Prosthet Dent 1999;81:300-4.)

Effect of processing method on the dimensional accuracy and water sorption of acrylic resin dentures

Acrylic Resin Reinforced With Chopped High Performance Polyethylene Fiber--Properties and Denture Construction

Statement of problem Discoloration of provisional prosthodontic materials may result in patient dissatisfaction and additional expense for replacement. Purpose The purpose of this study was to determine the color stability of 5 provisional prosthodontic materials before and after immersion in distilled water or coffee for 20 days or exposure to ultraviolet (UV) light for 24 hours. Material and methods A total of 105 disc-shaped specimens (20±0.1 mm by 1±0.05 mm) were fabricated with 5 provisional prosthodontic materials: polyethyl methacrylate resins (Trim II), polymethyl methacrylate resins (Duralay; Alike), and bis-acryl methacrylate resin (Luxatemp; Integrity), according to manufacturers' instructions (n=21). Seven specimens of each material were randomly selected and immersed individually in distilled water (60°C) or coffee (37°C) for 20 days or exposed to UV irradiation for 24 hours, respectively. Color was measured as CIE L ∗ a ∗ b ∗ with a colorimeter before and after the immersion or UV exposure. Color change (ΔE) was calculated and data were analyzed with 1-way ANOVA and the Tukey multiple comparisons test (α=.05). Results For specimens immersed in water, the color change of bis-acryl-methacrylate–based provisional materials (Integrity and Luxatemp) was significantly less than that of 3 methyl/ethyl methacrylate–based provisional materials (Trim II, Alike, and Duralay) ( P P P Conclusion Luxatemp and Integrity (bis-acryl-methacrylate–based resins) demonstrated acceptable color stability and were the most color-stable provisional prosthodontic materials tested compared to the methyl/ethyl methacrylate–based resins.

Tak W Chow

Papers

Ceramic dental biomaterials and CAD/CAM technology: state of the art.

Mechanical effectiveness of root canal irrigation

Effect of processing method on the dimensional accuracy and water sorption of acrylic resin dentures

Acrylic Resin Reinforced With Chopped High Performance Polyethylene Fiber--Properties and Denture Construction

Color stability of provisional prosthodontic materials.