Does clinical experience affect occlusal caries diagnosis and sealant recommendation? An in vitro study

The purpose of this in vitro study was to evaluate the effect of the length of clinical experience on clinician's diagnosing caries and recommending sealants on the occlusal surfaces of permanent/caries free third molars. The third molars involved in this study had been extracted prior to eruption. There were three study groups: dental students, clinicians with five to ten years experience, and clinicians with fifteen to twenty years of practice. Twenty-four percent of the entire sample diagnosed caries. Clinicians with five to ten years of practice diagnosed occlusal caries significantly more than clinicians with fifteen to twenty years of practice, but not significantly differently than senior dental students. Clinicians recommended sealants significantly more than dental students. The most frequent reason for sealant indication was prevention. The results indicate that clinical experience alone does not impart better caries diagnosis and sealant recommendation criteria.     

Does LLLT stimulate laryngeal carcinoma cells? An in vitro study

Low level laser therapy (LLLT) has been used successfully in biomedicine and some of the results are thought to be related to cell proliferation. The effects of LLLT on cell proliferation is debatable because studies have found both an increase and a decrease in proliferation of cell cultures. Cell culture is an excellent method to assess both effects and dose of treatment. The aim of this study was to assess the effect of 635nm and 670 nm laser irradiation of H.Ep.2 cells in vitro using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide). The cells were obtained from squamous cell carcinoma (SCC) of the larynx and were routinely processed from defrost to the experimental condition. Twenty-four hours after transplantation the cells were irradiated with doses ranging from 0.04 to 0.48J/cm2 for seven consecutive days (5 mW diode lasers: 635nm or 670 nm, beam cross-section approximately 1 mm) at local light doses between 0.04 and 0.48 J/cm2. The results showed that 635nm laser light did not significantly stimulate the proliferation of H.Ep.2 cells at doses of 0.04 J/cm2 to 0.48 J/cm2, However, 670nm laser irradiation led to an increased cell proliferation when compared to both control and 635nm irradiated cells. The best cell proliferation was found with 670nm laser irradiated cultures exposed to doses of doses of 0.04 to 0.48 J/cm2. We conclude that both dose and wavelength are factors that may affect cell proliferation of H.Ep.2 cells.     

Can herbal products be alternative root canal irrigation solutions in primary teeth? An in vitro study

ObjectivesTo evaluate antimicrobial properties and smear layer removal efficiency of various plant extracts and apple cider vinegar (AV).MethodsA total of 112 primary molars roots were randomly divided into two groups (n = 56) for antimicrobial test and infected with E faecalis and Candida albicans then divided again into 7 groups (n = 8) as physiological saline (PS), NaOCI, white tea (WT), Helichrysum arenarium (HA), AV, Citrus lemon (CL), and Anzer thyme (AT). Disinfecting abilities were measured with ImageJ. In the smear layer removal efficiency test, prepared 70 roots were divided into 7 groups (n = 10) as in the antimicrobial test also 2 subgroups were designed as with or without EDTA usage (n = 5). All samples were examined under SEM. Open dentin tubule percentage was evaluated with ImageJ.ResultsHA and CL showed higher antibacterial activity against E. faecalis than PS (p = 0.038, p = 0.009) Antifungal activity of AV against C. albicans was higher than saline (p < 0.001). AV in the coronal third and CL in the middle third removed more smear layer than saline and NaOCI (p < 0.05). In the coronal region, HA and AV showed similar smear layer removal efficacy to NaOCl + EDTA (p > 0.05). CL, HA, and AV presented statistically similar results to NaOCl + EDTA in smear layer removal efficacy in the middle region (p > 0.05).ConclusionsCL and AV have antimicrobial efficacy against E. faecalis and C. albicans respectively and smear layer removal activity.     

The effect of commonly used sutures on inflammation inducing pathogens – An in vitro study

IntroductionSutures are a vital part of nearly every surgical procedure designed to close and stabilize wound margins consequently allowing undisturbed wound healing.AimThe aim of this study was to evaluate in vitro antimicrobial effect of 4 commonly used sutures.Materials and methodsThe Direct Contact Test was used to evaluate the antibacterial properties of 4 types of sutures: 2 absorbable and 2 non-absorbable braided sutures, immediately or after aging for 2 or 7 days. The tested bacteria were: Staphylococcus epidermidis, Staphylococcus aureus and Pseudomonas aeruginosa. Three-way ANOVA, two-way ANOVA, one-way ANOVA and Tukey multiple comparison were used for statistical analysis.ResultsThe absorbable Vicryl Plus exhibited a bactericidal effect against the Staphylococcus strains, which was unaffected by aging. With P. aeruginosa, there was only an initial delay in bacterial growth. All other tested sutures did not have antibacterial effects against any of the tested bacteria (p < 0.001).ConclusionsVicryl Plus had sustained bactericidal effect against the Staphylococcus strains but not against P. aeruginosa. None of the other sutures presented any antibacterial properties.     

A non‐staining chlorhexidine mouthwash? Probably not: a study in vitro

Background and aim: Tooth staining is a common side effect of chlorhexidine mouth rinses and caused by the interaction of the di‐cationic antiseptic with dietary chromogens. A product is now available, which claims an anti‐discolouration system (ADS) with one clinical study in support. This study in vitro aims to determine whether two ADS rinses do or do not bind dietary chromogens. Method and materials: Optically clear acrylic specimens were cycled through human saliva (2 min), one of the three chlorhexidine rinses (two ADS and a positive control) (2 min) or water and then soaked in tea (60 min). After each cycle the optical density (OD) of specimens were read on a UV/visible spectrophotometer. The exit point was the cycle at which OD was >2.0. Results: All three rinses exceeded OD 2 at 11 cycles and there was no significant difference in staining for the ADS rinses compared with the positive control rinse. Conclusion: Based on extensive literature for the correlation of this test in vitro with chlorhexidine anti‐plaque activity and propensity to stain in vivo these ADS rinses will have the same anti‐plaque efficacy and potential to cause stain as established chlorhexidine rinse products.     

Does excessive occlusal load affect osseointegration? An experimental study in the dog

AIM: The purpose of this study was to evaluate the effect of excessive occlusal load following placement of titanium implants in the presence of healthy peri-implant mucosal tissues. MATERIALS AND METHODS: Mandibular bilateral recipient sites in six Labrador dogs were established by extracting premolars and molars. After 3 months, two TPS (titanium plasma sprayed) implants and two SLA (sandblasted, large grit, acid etched) implants were placed on each side of the mandible in each dog. Three implants were lost in the initial healing phase, leaving 45 implants for evaluation. Following 6 months of healing, gold crowns were placed on implants on the test side of the mandible. The crowns were in supra-occlusal contact with the opposing teeth in order to create excessive occlusal load. Implants on the control side were not loaded. Plaque control was performed throughout the experimental period. Clinical measurements and standardised radiographs were obtained at baseline and 1, 3 and 8 months after loading. At 8 months, the dogs were killed and histologic analyses were performed. RESULTS: At 8 months, all implants were osseointegrated. The mean probing depth was 2.5+/-0.3 and 2.6+/-0.3 mm at unloaded and loaded implants, respectively. Radiographically, the mean distance from the implant shoulder to the marginal bone level was 3.6+/-0.4 mm in the control group and 3.7+/-0.2 mm in the test group. Control and test groups were compared using paired non-parametric analyses. There were no statistically significant changes for any of the parameters from baseline to 8 months in the loaded and unloaded implants. Histologic evaluation showed a mean mineralised bone-to-implant contact of 73% in the control implants and 74% in the test implants, with no statistically significant difference between test and control implants. CONCLUSION: In the presence of peri-implant mucosal health, a period of 8 months of excessive occlusal load on titanium implants did not result in loss of osseointegration or marginal bone loss when compared with non-loaded implants.     

Does rotational strain at screw tightening affect the attainment or maintenance of osseointegration?

OBJECTIVES: This study investigated whether rotational strain affects osseointegration. MATERIAL AND METHODS: A total of 135 male rats were divided into five groups: 2-w rotation, 4-w rotation, 8-w rotation, 12-w rotation and control. Two hundred and seventy implants were inserted in rat tibia. The control group received no strain, while the 2-w, 4-w, 8-w and 12-w rotation groups received rotational strain at 2, 4, 8 and 12 weeks after implant placement, respectively. Removal torque (N cm) was measured in vivo. Bone contact rate (%) was calculated histomorphologically. Immunostaining for osteonectin (ON), osteopontin (OPN) and osteocalcin (OCN) was performed. The removal torque and bone contact rate were analyzed using one-way analyses of variance and the Scheffé method. RESULTS: At 4 weeks, the torque was significantly higher in the 2-w rotation group (1.30+/-0.44 N cm) than in the control group (0.79+/-0.67 N cm). From 8 to 16 weeks, the strained groups showed no significant differences from the control group. From the bone contact rates, bone formation was larger in the 4-week rotation group (62.9+/-10.7%) than in the control group (42.1+/-17.9%) at 8 weeks. The 4-week rotation group showed higher bone contact rate (61.1+/-11.3%) compared with the other strained groups and maintained this higher value until 16 weeks, showing no significant difference from the control group (72+/-5.2%). At the implant-bone interface, OPN was widely distributed and OCN was detected at a low level; however, ON could not be observed in any group. CONCLUSIONS: The bone contact rate changed when rotational strain was exerted at different periods after implant placement. However, the removal torque and distribution of extracellular matrix proteins were not adversely affected by the rotational strain.     

Do alveolar corticotomy or piezocision affect TAD stability? A preliminary study

The aim of this study was to evaluate the occurrence of interradicular temporary anchorage devices (TAD) loss installed to anchor canine retraction performed in association to alveolar corticotomy (AC) versus piezocision (PZ) surgeries. One hundred maxillary self-drilling TAD were installed in 50 patients who needed first maxillary premolars extractions. One week later, AC or PZ surgeries were performed surrounding the canine and the extraction sites. A group without any adjunct surgery to accelerate tooth movement was used as control. TAD stability was evaluated throughout the 6 months of canine retraction. A total of 7, 8 and 9 TAD were lost in the AC, PZ and control groups, respectively. No significant difference in TAD stability among the groups was observed (p > 0.05). Despite the increased inflammatory response due to AC or PZ, TAD stability was not compromised.     

Effect of locator abutment height on the retentive values of pink locator attachments: An in vitro study

Statement of problem

Currently, no guidelines exist to help in the selection of Locator abutments for implants at different heights.

Comparison of volumetric analysis of lateral compaction & three different vertically compacted thermoplasticized obturation techniques using spiral CT – An in vitro study

The objective of endodontic obturation is to provide a complete seal along the length of root canal system. This study was conducted to compare volumetrically, the laterally compressed gutta percha with three different vertically compacted thermoplasticized obturating systems using spiral CT, an in vitro study. Materials and methods included preparation of access cavities in 20 single rooted mandibular first premolars, followed by cleaning and shaping. Obturation was done with different thermoplasticized obturation systems: Group A – cold lateral; Group B – Calamus dual; Group C – E & Q Plus; Group D – Obtura II. Volume analysis was done using spiral computed tomography (CT). The percentage difference was calculated & statistically analyzed using one-way ANOVA and multiple comparisons between groups using Tukey's HSD test. The results of study has shown the statistical significance between all the groups with the p-value <0.0001. Multiple comparisons between different groups show statistical significance in all groups except Group C and Group D. With this significance in results, it can be concluded that Calamus dual showed the highest volume of obturation, followed by Obtura II and E & Q Plus. The least volume of obturation was observed in cold lateral condensation technique.     

Chlorhexidine-modified glass ionomer for band cementation? An in vitro study

OBJECTIVE: To compare the mean retentive strength, predominant site of band failure, amount of cement remaining on the tooth at deband and survival time of orthodontic micro-etched bands cemented with chlorhexidine-modified (CHXGIC) or conventional glass ionomer cement (GIC). DESIGN: In vitro study. SETTING: Dental Materials Laboratory. MATERIALS AND METHODS: One-hundred-and-twenty intact, caries-free third molars were collected from patients attending for third molar surgery. These were stored for 3 months in distilled water and decontaminated in 0.5% chloramine. To assess retentive strength, 80 teeth were randomly selected and 40 were banded with each cement. Testing was undertaken using a Nene M3000 testing machine at a cross-head speed of 1 mm/min. Following debanding, the predominant site of failure was recorded as cement-enamel or cement-band interface. The amount of cement remaining on the tooth surface following deband was assessed and coded. Survival time for another 40 banded specimens, 20 cemented with each cement, was assessed following application of mechanical stress in a ball mill. MAIN OUTCOME MEASURES: Retentive strength, predominant site of failure, amount of cement remaining on the tooth surface, survival time. RESULTS: Mean retentive strength for bands cemented with CHXGIC (0.32 MPa, SD 0.09) or GIC (0.28 MPa, SD 0.07) did not differ significantly (p=0.05). All bands failed at the enamel-cement interface. There was no significant difference in the amount of cement remaining on the tooth surface after deband for each cement type (p=0.23). The mean survival time of bands cemented with CHXGIC or GIC was 7.0 and 6.4 hours, respectively (p=0.23). CONCLUSIONS: There was no significant difference in mean retentive strength, amount of cement remaining on the tooth after deband or mean survival time of bands cemented with CHXGIC or GIC. Bands cemented with either cement failed predominantly at the enamel-cement interface. The results suggest that CHXGIC may have comparable clinical performance to GIC for band cementation.     

Bonding with self-etching primers--pumice or pre-etch? An in vitro study

The purpose of this study was to compare the shear bond strengths (SBSs) of orthodontic brackets bonded with self-etching primer (SEP) using different enamel surface preparations. A two-by-two factorial study design was used. Sixty human premolars were harvested, cleaned, and randomly assigned to four groups (n = 15 per group). Teeth were bathed in saliva for 48 hours to form a pellicle. Treatments were assigned as follows: group 1 was pumiced for 10 seconds and pre-etched for 5 seconds with 37 per cent phosphoric acid before bonding with SEP (Transbond Plus). Group 2 was pumiced for 10 seconds before bonding. Group 3 was pre-etched for 5 seconds before bonding. Group 4 had no mechanical or chemical preparation before bonding. All teeth were stored in distilled water for 24 hours at 37°C before debonding. The SBS values and adhesive remnant index (ARI) score were recorded. The SBS values (± 1 SD) for groups 1-4 were 22.9 ± 6.6, 16.1 ± 7.3, 36.2 ± 8.2, and 13.1 ± 10.1 MPa, respectively. Two-way analysis of variance and subsequent contrasts showed statistically significant differences among treatment groups. ARI scores indicated the majority of adhesive remained on the bracket for all four groups. Pre-etching the bonding surface for 5 seconds with 37 per cent phosphoric acid, instead of pumicing, when using SEPs to bond orthodontic brackets, resulted in greater SBSs.     

Does lag screw fixation of condylar fractures result in adequate stability? A finite element analysis

The great incidence and controversies related to the diagnosis, treatment, surgical accesses, and type of osteosynthesis materials confer an outstanding role to condylar fractures among facial fractures. Plate configurations, with diverse formats and sizes, may be used to surgically resolve condylar fractures. With the purpose of improving the advantages and minimizing the disadvantages of fixation techniques, the neck screw was developed aiming at the needed stabilization to render a correct fixation through a system of dynamic compression. This is achieved by increasing the contact between the fractured bone stumps, as well as assisting at the time of fracture reduction. The present paper aims at comparing the fixation and stability of mandibular condylar fractures using the neck screw and an overlaid “L”-shaped-4-hole-2 mm plate on the one hand, with a system in which the neck screw and the “L”-shaped plate form a single structure, having been joined by a welded point, on the other hand. The results with the neck screw are satisfactory, and, thus, it is an alternative for the reduction and fixation of fractures of the mandibular condyle, whether or not a plate is joined to the structure, provided it is correctly prescribed and with adequate surgical sequence and technique.     

Does malocclusion affect masticatory performance?

This purpose of this study was to evaluate the largely untested assumption that malocclusion negatively affects masticatory performance. A sample of 185 untreated subjects (48% male and 52% female) from 7 to 37 years of age, representing subjects with normal occlusion (n = 38), Class I (n = 56), Class II (n = 45), and Class III (n = 46) malocclusion, were evaluated. Masticatory performance was evaluated objectively using artificial (CutterSil, median particle size and broadness of the distribution) and real foods (number of chews for jerky and almonds), and subjectively using a visual analog scale. The results showed no significant differences in age or the body mass index (Wt/Ht2) between the occlusion groups. Subjects with normal occlusion had significantly smaller particle sizes (P = .001) and broader particle distributions (P < .001) than subjects with malocclusion. Compared with the normal occlusion group, the median particle sizes for the Class I, II, and III malocclusion groups were approximately 9%, 15%, and 34% larger, respectively. There were also significant group differences in their subjective ability to chew fresh carrots or celery (P = .019) and firm meat (P = .003). Class III subjects reported the greatest difficulty, followed by Class II subjects, Class I subjects, and subjects with normal occlusion, respectively. We conclude that malocclusion negatively affects subjects' ability to process and break down foods.     

Does plate adaptation affect stability? A biomechanical comparison of locking and nonlocking plates.

PURPOSE: The purpose of this investigation was to determine whether the degree of plate adaptation and effects of locking influenced the mechanical behavior of the plate/screw/substrate system for 2.0-mm monocortical superior border plates and 2.4-mm reconstruction plates secured at the inferior border intended to stabilize simulated mandibular angle fractures. MATERIALS AND METHODS: A total of 130 polyurethane synthetic mandible replicas (Synbone, Landquart, Switzerland) were used in this investigation. Five controls each, for incisal edge and molar loading, as well as 5 samples each for 2.4-mm locking and nonlocking reconstruction plates and 2.0-mm locking and nonlocking monocortical superior border plates, intimately adapted (0.0-mm offset), 1.0-mm offset and 2.0-mm offset were subjected to loading at the incisal edge and molar region with an Instron 1331 (Instron Corp, Canton, MA) servohydraulic mechanical testing unit. Load/displacement data were recorded, and yield load, yield displacement, and stiffness were determined. Mean and standard deviation values were calculated. Statistically significant differences were determined for the effects of locking and degree of plate adaptation using a 1-way analysis of variance (P <.05). For differences within categories and among groups, a Sheffé multiple-comparison test was performed. First-order polynomial best-fit curves were created for each group to further evaluate and compare the mechanical behavior. RESULTS: There were no statistically significant differences (P <.05) for yield load, yield displacement, and stiffness within the 2.4 and the 2.0 locking categories for both molar and incisal edge loading. For the 2.4 nonlocking category, there were statistically significant differences for yield load, yield displacement, and stiffness between the 0.0-mm offset group and both the 1.0-mm and 2.0-mm offset groups for both molar and incisal edge loading but not between the 1.0-mm and 2.0-mm groups. For the 2.0 nonlocking category, there were statistically significant differences for yield load, yield displacement, and stiffness between both the 0.0-mm and 1.0-mm offset groups and the 2.0-mm offset group for both molar and incisal edge loading but not between the 0.0-mm and 1.0-mm groups. CONCLUSIONS: The degree of adaptation (amount of offset) affected the mechanical behavior of the nonlocking systems evaluated. It did not affect the locking systems. Failure occurred as an "all-or-nothing" pattern.