Success rates of single-thread and double-thread orthodontic miniscrews in the maxillary arch.

AIM: There is limited research on the clinical performance of double-thread orthodontic miniscrews. This study aimed to compare the stability of double-thread and single-thread orthodontic miniscrews and identify the potential associations between patient-related and location-related factors with miniscrew stability. METHODS: This retrospective cohort study involved 90 orthodontic miniscrews (45 single-thread, 45 double-thread) with identical dimensions (8 mm length, 1.6 mm diameter). The screws were inserted in various locations within the upper jaw of 83 patients (54 females, 29 males; mean age = 15.1 ± 2.4 years). Failure was defined as excessive mobility or loss of miniscrew after placement. The data recorded were patient age, gender, insertion site, side of insertion (buccal or lingual), duration of force application, and failure occurrence. RESULTS: The overall success rate within the sample was 92.2%. Double-thread miniscrews exhibited a significantly higher success rate than single-thread miniscrews (P = 0.049), with 97.8% and 86.7% success rates, respectively. Gender, age, insertion location, and side of insertion did not show significant associations with failure (P > 0.05). Log-rank analysis revealed a significant difference between the two groups (P = 0.046), indicating a higher probability of survival for the double-thread design. CONCLUSIONS: The overall success rate of orthodontic miniscrews was high in the present sample. Double-thread miniscrews placed in various locations within the maxillary arch demonstrated superior stability and survival rates compared to their single-thread counterparts. Therefore, double-thread miniscrews may be preferred when bone quality is inadequate, such as in young patients.

Antimicrobial photodynamic therapy against Lactobacillus casei using curcumin, nano-curcumin, or erythrosine and a dental LED curing device.

This study aimed to investigate the photodynamic effects of curcumin, nanomicelle curcumin, and erythrosine on Lactobacillus casei (L. casei). Various concentrations of curcumin (1.5 g/L, 3 g/L), nano-curcumin (3 g/L), and erythrosine (100 µM/L, 250 µM/L) were tested either alone or combined with light irradiation (PDT effect) against L. casei in planktonic and biofilm cultures. The light was emitted from a light-emitting diode (LED) with a central wavelength of 450 nm. A 0.12% chlorhexidine digluconate (CHX) solution served as the positive control, and a solution containing neither photosensitizer nor light was the negative control group. The number of viable microorganisms was determined using serial dilution. There was a significant difference in the viability of L. casei in both planktonic and biofilm forms (P < 0.05). In the planktonic culture, the antibacterial effects of CHX and PDT groups with curcumin 3 g/L and erythrosine 250 µM/L were significantly greater than the other groups (P < 0.05). For L. casei biofilms, the greatest toxic effects were observed in CHX and PDT groups with curcumin 3 g/L, erythrosine 250 µmol/L, erythrosine 100 µmol/L, and nanomicelle curcumin 3 g/L, with a significant difference to other groups (P < 0.05). The antibacterial effects of all photosensitizers (except erythrosine 250 µmol/L at planktonic culture) enhanced significantly when combined with light irradiation (P < 0.05). PDT with curcumin 3 g/L or erythrosine 250 µmol/L produced comparable results to CHX against L. casei at both planktonic and biofilm cultures. Alternatively, PDT with erythrosine 100 µmol/L or nanomicelle curcumin 3 g/L could be suggested to kill L. casei biofilms.

Frontal Sinus Fractures: An Evaluation of Patient Demographics, Mechanisms of Injury, Classification, and Management Strategies in Patients Referred to a Trauma Center, From 2014 to 2019.

This retrospective study aimed to present demographic data, mechanisms of injury, anatomical locations, and management strategies in patients with frontal sinus fractures. The study included 91 patients with frontal sinus fractures attending the Rajaee Hospital of Shiraz between 2014 and 2019. The data recorded for each patient included age, sex, injury mechanism, fracture classification, associated craniofacial fractures, nasofrontal duct injury, cerebrospinal fluid leak, and treatment approach. The mean age of patients was 31.0±14.0 years, with male predominance (95.6%). Car crashes represented the most frequent mechanism of frontal sinus fracture, involving 31 subjects (34%). Isolated anterior and posterior table fractures were seen in 32 (35.2%) and 5 (5.5%) patients. Fifty-four patients (59.3%) presented both tables' involvement. Frontal sinus injuries occurred frequently (74.7%) with other facial fractures. Nasofrontal duct injury was found in 7 patients (7.7%), and 13 (14.3%) exhibited cerebrospinal fluid leakage. Fifty patients (55%) were treated with observation alone; 16 (17.5%) underwent sinus preservation, 12 (13.2%) experienced sinus obliteration, and 13 (14.3%) endured cranialization. Fisher's exact test revealed no significant association between the classification of fracture and the mechanism of injury (P=0.591). However, a significant association was observed between the fracture classification and the treatment applied (P=0.023). Frontal sinus fractures were most often caused by car crashes in young adults. Combined anterior and posterior table fractures were more commonly found than isolated anterior or posterior table involvement. Most frontal sinus fractures were treated conservatively without DDS surgical operation.

Mandibular Canal Branching Assessed With Cone-Beam Computed Tomography.

This study aimed to evaluate the prevalence and type of mandibular canal branching in a sample of the Iranian population through cone-beam computed tomography (CBCT) images. This cross-sectional study was performed on CBCT records of 300 patients (112 males and 188 females; mean age 30.14 ± 10.96 y). The presence of mandibular canal branch (MCB) was evaluated by reconstructing multiple panoramic views and buccolingual cross-sections, according to Naitoh's classification. The prevalence of MCB, the type of MCB, and the demographic information of all patients were recorded. The maximum number of branching and the maximum type of branching were also registered for each patient. Mandibular canal branching was observed in 131(43.7%) of 300 CBCT images without side or sex differences ( P > 0.05). The most frequent type was dental, followed by the retromolar, forward, and buccolingual types, respectively. There was a statistically higher frequency of retromolar canal in females than in males (odds ratio: 1.14 ± 4.25; P = 0.013). About 46% of patients with MCB had more than one accessory canal and 29% displayed more than one type of MCB. The coincidence of dental and retromolar canals in a patient was the most prevalent combination. Considering the relatively high prevalence of MCB (43.7%), it is recommended to keep in mind the possibility of anatomical variations of the inferior alveolar nerve during dental procedures to avoid postsurgical complications. The high possibility of observing multiple numbers and types of branching in the patients should also be considered during preoperative assessments.

Clinical and radiographic effectiveness of mineral trioxide aggregate (MTA) partial pulpotomy with low power or high power diode laser irradiation in deciduous molars: a randomized clinical trial.

This study investigated the clinical and radiographic effectiveness of MTA partial pulpotomy with low power or high power diode laser irradiation in primary molars. In this randomized single-blind clinical trial, 63 mandibular second molars were assigned into three groups (n = 21). After pulp amputation and achieving hemostasis, MTA was placed over pulp stumps in group 1 (MTA). The patients in groups 2 (LLLT-MTA) and 3 (DL-MTA) underwent low level (660 nm, 200 mW) and high power (810 nm, 1 W) diode laser radiation prior to MTA placement, respectively. The occurrence of clinical failure (spontaneous pain, tenderness upon percussion, swelling, fistula, mobility) and radiographic failure (periodontal ligament widening, external or internal root resorption, periapical or furcal radiolucency) was recorded up to 18 months after therapy. MTA and LLLT-MTA groups showed clinical success rate of 100% throughout the experiment. The clinical success rate of DL-MTA group was 95.2%, 95.2%, and 87.5% after 6, 9, and 18 months. The radiographic success rates were 90.5%, 90.5%, and 87.5% in the MTA group; 100%, 95.2%, and 88.2% in the LLLT-MTA group, and 85.7%, 76.2%, and 68.7% in the DL-MTA group, at 6-, 9-, and 18-month follow-ups, respectively. No significant differences were found in the frequency of clinical or radiographic failure among the groups at any interval (p > 0.05). MTA partial pulpotomy was a suitable technique for vital pulp therapy in deciduous teeth. The addition of low power or high power diode laser radiation to the procedure did not cause a significant difference in success rate values.

Does the application of whitening dentifrices during at-home bleaching affect the bond strength of resin composite to dentin?

AIM: This study aimed to evaluate the effect of using whitening dentifrices during at-home bleaching on the shear bond strength (SBS) of resin composite to dentin, and investigate whether the increased polymerization time would improve SBS. METHODS: Ninety-six bovine incisors were divided into 4 groups of 24, according to the whitening treatment applied as follows: group 1, at-home bleaching + brushing with a regular dentifrice; group 2, at-home bleaching + brushing with a whitening dentifrice containing ozone; group 3, at-home bleaching + brushing with a commercial whitening dentifrice; and group 4 (control), no whitening/brushing treatment. Each group was divided into two subgroups (n = 12) to assess the effect of curing time (20 versus 80 s) on SBS. A self-etch adhesive was bonded to dentin, and after 2-day water storage, SBS was determined. RESULTS: SBS was significantly affected by the whitening treatment (P = 0.03), but increasing the curing time had no significant effect on SBS (P = 0.137). Bond strength in group 1 was comparable to the control group (P > 0.05). The specimens in group 3 displayed significantly lower SBS than either group 4 or group 1 (P > 0.05). No significant difference was observed between the SBS of group 2 compared to any other group (P > 0.05). There was no significant association between the treatment group and failure type (P > 0.05). CONCLUSION: The bonding interface was not negatively influenced by the at-home bleaching procedure. However, using a commercial whitening dentifrice during at-home bleaching produced a significant detrimental effect on SBS. Extending the curing time would have no beneficial effect on adhesion to a whitened dental substrate.

The Efficacy of 4% Articaine Versus 2% Lidocaine in Inducing Palatal Anesthesia for Tooth Extraction in Different Maxillary Regions.

PURPOSE: This study was conducted to ascertain the efficacy of buccal injection of articaine compared to lidocaine in inducing palatal anesthesia in different maxillary regions. MATERIALS AND METHODS: This double-blinded, randomized clinical trial included 300 patients who referred for extraction of 1 maxillary tooth. The patients were categorized into 3 strata according to the extraction area (anterior, premolar, molar), and then randomly assigned to 2 groups based on the administered medication. The first group received buccal infiltration by 0.6 mL of 2% lidocaine, whereas the second group was buccally administered using 0.6 mL of 4% articaine. After a waiting period of 2 minutes, the failure or success in achieving palatal anesthesia was assessed by the instrumentation technique. In cases of failed anesthesia, an additional 0.6 mL of the same anesthetic was given, and the procedure was repeated if palatal anesthesia was not attained after a 2-minute delay. If pain remained 2 minutes after the third injection, a supplemental palatal infiltration was administered and the extraction was attempted. RESULTS: The success rate of buccal infiltration in achieving palatal anesthesia was 82.7% in the articaine group and 1.3% in the lidocaine group. There was a significant difference in the success rate and drug volume required to induce palatal anesthesia between the 2 groups (P < .001), but no significant difference was found between different maxillary regions, using either of the medications (P > .05). CONCLUSIONS: Articaine can be considered as a suitable alternative to lidocaine for eliminating painful palatal infiltration in the extraction of maxillary teeth.

Does the application of GaAlAs laser and platelet-rich plasma induce cell proliferation and increase alkaline phosphatase activity in human dental pulp stem cells?

Blood extracts containing platelet products are gaining popularity in promoting healing and pulp regeneration. This study was designed to evaluate the effect of platelet-rich plasma (PRP) and gallium-aluminum-arsenide (GaAlAs) laser on proliferation and differentiation of human dental pulp stem cells (hDPSCs). In this ex vivo study, hDPSCs isolated from impacted mandibular third molars were cultured in Dulbecco's Modified Eagle's medium )DMEM(with 10% fetal bovine serum (FBS). After reaching the desired confluence, the cells were distributed into 4 groups, namely, control, PRP, laser, and PRP+laser for MTT assay and alkaline phosphatase (ALP) test. In the PRP and PRP+laser groups, 10% PRP was added to each well on the plate. In the laser and PRP+laser groups, as for the proliferation test, laser irradiation was carried out for 45 s, while 135 s was designated for ALP test. After 1, 3, and 5 days, cell proliferation and ALP activity were assessed using MTT and ALP colorimetric assay, respectively. Two-way ANOVA was utilized to analyze data. In PRP and PRP+laser groups, cell proliferation and viability increased until day 3 but began to decline afterwards until the 5th day. In the laser group, the increase in proliferation and viability was observed till day 5 which was less than the control group. Laser and control groups exhibited significantly higher cell viability and proliferation than both PRP and PRP+laser groups. ALP activity was more pronounced in PRP+laser, PRP, and laser in descending order; however, all were less than that of the control group. Only in the control group did the ALP activity augment during the 5-day period. Laser irradiation could induce pulp cell proliferation and demonstrated a better performance than PRP in this regard.

Low level laser therapy, Er,Cr:YSGG laser and fluoride varnish for treatment of dentin hypersensitivity after periodontal surgery: A randomized clinical trial.

This clinical trial aimed to compare the effects of low-level laser therapy (LLLT), Er,Cr;YSGG laser, and fluoride varnish, as compared to the placebo laser on decreasing dentin hypersensitivity (DH). This randomized, double-blinded clinical trial included 60 jaw quadrants in 24 patients who underwent periodontal surgery. The quadrants were randomly assigned to 4 groups and received treatments as follows. Group 1: LLLT with a combination of red and infrared wavelengths, group 2: Er,Cr:YSGG laser (0.25 W and 0.5 W), group 3: fluoride varnish, and group 4: placebo laser. The sensitivity response to the cold spray was recorded using visual analogue scale (VAS) at baseline, immediately, and 1 week post-treatment. The data were analyzed by repeated measures analysis at the significance level of P<0.05. There was a significant reduction in DH after treatment by low-level lasers, Er,Cr:YSGG laser, or fluoride varnish compared to the baseline data (P<0.05), but the placebo group displayed no significant alteration in DH (P=0.069). At 1 week, the VAS score in the Er,Cr:YSGG laser group was significantly lower than that of the LLLT (P= 0.043) and placebo (P<0.001) groups. Furthermore, the subjects who received fluoride varnish exhibited significantly lower DH compared with the placebo group (P = 0.023). Er,Cr:YSGG laser was the most effective strategy in dealing with DH, as it caused the greatest pain reduction over the study period and showed a significant superiority over LLLT and placebo groups. Alternatively, the application of fluoride varnish could be recommended for attenuating DH following periodontal surgery.

The validity of laser fluorescence (LF) and near-infrared reflection (NIRR) in detecting early proximal cavities.

OBJECTIVES: Diagnosing cavitated proximal lesions is important for therapeutic decisions. This clinical study aimed to determine the validity of laser fluorescence (LF) and near-infrared reflection (NIRR) techniques for detecting early proximal cavities. MATERIALS AND METHODS: The study included 43 proximal surfaces in 15 females who had limited radiolucent lesions in their bitewing radiographs. The approximal areas of interest were assessed by DIAGNOdent Pen (LF) and the Proxi interchangeable head of VistaCam iX intraoral camera (NIRR). Finally, orthodontic separators were placed in the contact points to provide enough space between the teeth. The sensitivity, specificity, and accuracy of diagnosing cavitated proximal surfaces were calculated for LF and NIRR against direct visual and tactile examination as the reference standard. RESULTS: On the basis of the reference standard, 34 surfaces (79.1%) were not cavitated, whereas 9 surfaces (20.9%) were cavitated and in need of restoration. The sensitivity, specificity, and accuracy of LF were 44.4%, 61.8%, and 58%, and those of NIRR were 88.9%, 14.7%, and 30%, respectively. CONCLUSIONS: The VistaCam iX Proxi was more sensitive and DIAGNOdent Pen was more specific in detection of proximal cavities. However, none of the techniques was accurate enough to be recommended as a sole approach for proximal caries detection. CLINICAL RELEVANCE: LF showed an overall superior diagnostic performance to NIRR for diagnosing proximal cavitation in permanent posterior teeth. Within the limitations of this study, neither VistaCam iX Proxi nor DIAGNOdent Pen could be considered a suitable device for diagnosing proximal cavities.

A randomized clinical trial comparing the efficacy of low-level laser therapy (LLLT) and laser acupuncture therapy (LAT) in patients with temporomandibular disorders.

This study compared the efficacy of low-level laser therapy (LLLT) versus laser acupuncture therapy (LAT) in patients with temporomandibular disorders (TMDs). In this randomized, double-blind clinical trial, 45 TMD patients were randomly divided into three groups. In group 1 (LLLT), a GaAlAs laser was applied on painful masticatory muscles and TMJs (810 nm, 200 mW, 30 s per point, Gaussian beam, spot size 0.28 cm2, 21 J/cm2) two times a week for 5 weeks. In group 2 (LAT), the laser was emitted bilaterally on acupuncture points (ST6, ST7, LI4) with the same settings as the LLLT group. Group 3 (placebo) underwent treatment with sham laser. The patients were evaluated before treatment (T1), after 5 (T2) and 10 (T3) laser applications, and 1 month later (T4). The mandibular range of motion as well as pain intensity in masticatory system was recorded at each interval. There was no significant difference in mouth opening between the groups (p > 0.05), but the amount of lateral excursive and protrusive movements was significantly greater in LLLT and LAT groups than the placebo group at some intervals (p < 0.05). The overall pain intensity and pain degree at masticatory muscles (except temporal muscle) and TMJs were significantly lower in both experimental groups than the placebo group at most intervals after therapy (p < 0.05). Both LLLT and LAT were effective in reducing pain and increasing excursive and protrusive mandibular motion in TMD patients. LAT could be suggested as a suitable alternative to LLLT, as it provided effective results while taking less chair time.

Does the Winter or Pell and Gregory Classification System Indicate the Apical Position of Impacted Mandibular Third Molars?

PURPOSE: The present study investigated the relationship of impacted mandibular third molars to the cortical plates and inferior alveolar canal (IAC) using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: The present study included CBCT images of 386 lower third molars in 226 patients, for whom the initial panoramic radiographs had revealed a close relationship between the third molars and IAC. The coronal images were prepared to determine the position of apex about the buccal and lingual cortexes and IAC. The impacted third molars were categorized using the Winter and the Pell and Gregory classifications. The relationship between the third molars and buccal/lingual cortexes and IAC was determined in the different classes of the Winter and the Pell and Gregory systems. RESULTS: The mesioangular position was more prevalent in the present sample. Most teeth were Class I concerning the ascending ramus and level C in depth. Generally, the impacted mandibular third molars showed a lingual position and were in contact or intersecting into the IAC. A significant association was found between the type of tooth impaction using the Winter and the Pell and Gregory classifications and the position of the third molar teeth concerning the cortical plates and IAC. CONCLUSIONS: The possibility of the buccal position of the tooth and the chance of an intersection of the apex into the IAC was greater in teeth that were mesioangular and were Class III concerning the ascending ramus and level C in depth. These data should be considered during the preoperative assessment of third molars to reduce postoperative complications.

The Electrical Activity of Masseter and Anterior Temporal Muscles in Patients With Unilateral Cleft Lip and Palate.

This study aimed to determine the electrical activity of masseter and anterior temporal muscles in patients with unilateral cleft lip and palate (CLP) and compare it with healthy volunteers. The study involved 20 female patients (mean age 20 ±â€Š4 years) with unilateral cleft lip and palate who had undergone lip and palate surgery in childhood and finished the first-phase orthodontic therapy with level and align teeth. Twenty age- and sex-matched volunteers with no cleft lip and palate were involved as controls. Electromyographic (EMG) signals of masseter and anterior temporal muscles were recorded at rest position, during swallowing and during maximum bite force (MBF). EMG signals at different test conditions were compared between the cleft and noncleft sides of CLP patients and between CLP patients and healthy individuals. The EMG potentials of masseter (rest, swallowing, MBF) and temporal (rest, MBF) muscles were significantly higher in the cleft than the noncleft side of CLP patients (P value <0.001). Generally, patients with unilateral cleft lip and palate experienced a significant increase in the electrical activity of the masseter and temporal muscles in both sides compared to the control group (P <0.05). In conclusion, patients with unilateral cleft lip and palate exhibit overall greater masticatory muscle activity compared to healthy individuals. The asymmetric masticatory function in subjects with unilateral cleft lip and palate may be associated with severe consequences such as asymmetric facial growth, implying the importance of early diagnosis and orthodontic treatment to achieve a favorable environment for balanced facial growth in CLP affected patients.

Is Low-Level Laser Therapy Effective for Treatment of Neurosensory Deficits Arising From Sagittal Split Ramus Osteotomy?

PURPOSE: This study investigated the effectiveness of low-level laser therapy (LLLT) for treating neurosensory impairment after bilateral sagittal split osteotomy (BSSO). MATERIALS AND METHODS: This randomized, double-blinded, split-mouth trial included patients requiring BSSO. After surgery, 1 side of each patient was randomly assigned to laser therapy and the other side served as the control. At 24, 48, and 72 hours after surgery, LLLT was accomplished by intraoral application of a 660-nm laser around the surgical site (200 mW, 10 seconds, 2 J, 1.5 J/cm2) followed by extraoral irradiation by an 810-nm laser (200 mW, 10 seconds, 2 J, 7 J/cm2) along the distribution of the inferior alveolar nerve. Subsequently, extraoral irradiation was repeated 2 times per week for 3 weeks along the path of the inferior alveolar nerve, lower lip, and chin. On the control side, the treatment was similar to the laser side but with laser simulation. The main outcome was assessing nerve damage by a "2-point discrimination test" before and up to 60 days after surgery. RESULTS: The sample consisted of 16 patients. No significant difference was found between the laser and control sides before and after surgery and on postoperative days 15 and 30 (P > .05). The 2-point discrimination distance was significantly shorter on the laser side than on the control side on postoperative days 45 and 60 (P < .05). CONCLUSION: LLLT was effective in the treatment of neurosensory disturbances arising from BSSO. Therefore, LLLT can be recommended to accelerate the recovery of sensory aberrations in patients undergoing BSSO.

Is Low-Level Laser Therapy Effective in the Management of Pain and Swelling After Mandibular Third Molar Surgery?

PURPOSE: This study evaluated the effect of low-level laser therapy (LLLT) on decreasing pain and swelling after removal of impacted third molars. PATIENTS AND METHODS: This randomized, double-blinded, split-mouth study included patients presenting 2 symmetrically impacted mandibular third molars. In each participant, one side was randomly assigned to laser treatment and the other side received placebo. LLLT was performed by intraoral application of a 660-nm laser (200 mW, 6 J per point at 4 points) followed by extraoral application of an 810-nm laser (200 mW, 6 J per point at 3 points). Irradiation at the 810-nm wavelength was repeated on days 2 and 4 after surgery. On the control side, the treatment protocol was similar to the experimental side, but with laser simulation. The main outcomes were the degree of pain during the next 7 days and the edema coefficients on days 2, 4, and 7 after surgery. Data were analyzed using generalized linear models to determine the effect of group and time on pain level and edema coefficients. RESULTS: The final sample consisted of 40 patients. Pain level was significantly lower in the laser than in the placebo side at all time points during the experiment (P < .05). Swelling was significantly lower in the laser than in the placebo group on days 2, 4, and 7 after surgery (P < .05). CONCLUSION: LLLT proved effective in decreasing the intensity of pain and swelling after removal of impacted third molars and can be recommended to alleviate patients' symptoms after surgery.

Effect of low-level laser therapy on tooth sensitivity induced by in-office bleaching.

This study aimed to investigate the effect of low-level laser therapy (LLLT) on tooth sensitivity induced by in-office bleaching. Sixty-six patients enrolled in this randomized clinical trial. Following the in-office procedure with 40% hydrogen peroxide, the participants were randomly divided into three groups. The patients in group 1 received irradiation from a low-level red laser (LLRL; 660 nm, 200 mW, 15 s, 12 J/cm(2)), whereas participants in group 2 were subjected to a low-level infrared laser (LLIL; 810 nm) under similar conditions as in group 1. In group 3 (placebo), the laser treatment was the same as that in groups 1 and 2, but without energy output. The degree of tooth sensitivity was recorded at 1, 24, and 48 h after bleaching using a visual analog scale (VAS). The change in tooth shade was measured 30 days after tooth whitening. The intensity of tooth sensitivity was not significantly different between groups at 1 h after bleaching (p > 0.05). At 24 h after therapy, pain level was significantly lower in the LLIL group compared to the LLRL and placebo groups (p < 0.05). At 48 h after bleaching, VAS scores in the LLIL and LLRL groups were comparable to each other (p > 0.05) and both were significantly lower than that of the placebo group (p < 0.05). There was no significant difference in the efficacy of tooth whitening among groups (p > 0.05). LLLT with an infrared diode laser could be recommended as a suitable strategy to reduce the intensity of tooth sensitivity after in-office bleaching.

Effect of Different Surface Treatments and Thermocycling on Bond Strength of a Silicone-based Denture Liner to a Denture Base Resin.

AIM: The aim of this study is to evaluate the effects of three different surface treatments and thermocycling on the tensile strength of a silicone lining material to denture resin. MATERIALS AND METHODS: A total of 96 cube-shaped specimens were fabricated using heat-cured polymethyl methacrylate (PMMA) denture base resin. Three millimeters of the material was cut from the midsection. The specimens were divided into four groups. The bonding surfaces of the specimens in each group received one of the following surface treatments: no surface treatment (control group), airborne particle abrasion with 110 pirn alumina particles (air abrasion group), Er:yttrium aluminum garnet laser irradiation (laser group), and air abrasion + laser. After the lining materials were processed between the two PMMA blocks, each group was divided into two subgroups (n = 12), either stored in distilled water at 37°C for 24 hours or thermocycled between 5 and 55°C for 5,000 cycles. The specimens were tested in tensile and shear strength in a universal testing machine. Data were analyzed with two-way analysis of variance and Tamhane's post hoc tests (α = 0.05). The mode of failure was determined, and one specimen in each group was examined by scanning electron microscopy. RESULTS: Surface-treated groups demonstrated significantly higher tensile strengths compared to the control group (p < 0.001). Nonetheless, no significant differences were found between surface-treated groups (p > 0.05). The tensile strength was significantly different between thermocycled and water-stored specimens (p = 0.021). CONCLUSION: Altering the surface of the acrylic denture base resin with air abrasion, laser, and air abrasion + laser increased the tensile strength. Thermocycling resulted in decrease in bond strength of silicone-based liner to surface-treated acrylic resin. CLINICAL SIGNIFICANCE: Pretreatment of denture base resins before applying the soft liner materials improves the bond strength. However, thermocycling results in decrease in bond strength of soft denture liner to surface-treated acrylic resin.

A randomized clinical trial of the effect of low-level laser therapy before composite placement on postoperative sensitivity in class V restorations.

This study aimed to investigate the efficacy of low-level laser irradiation when applied just before placement of resin composite on reducing postoperative sensitivity of class V lesions. In this randomized clinical trial, 31 patients with 62 class V cavities were included (two teeth in each participant). The teeth were randomly assigned into laser and placebo groups. After cavity preparation, the teeth in the experimental group were subjected to irradiation from a low-power red laser (630 nm, 28 mW, continuous wave, 60 s, 1.68 J), which was applied for 1 min on the axial wall of the cavity. In the control group, the same procedure was performed but with laser simulation. Then, a self-etch adhesive was applied and the cavities were restored with a microhybrid resin composite. Before treatment and on days 1, 14, and 30 after treatment, tooth sensitivity to a cold stimulus was recorded using a visual analogue scale. Data were analyzed by Friedman and Wilcoxon signed-rank tests (p < 0.05). Pain scores after restorative procedures were significantly lower in the laser group compared to the placebo application (p < 0.05). Although both groups experienced a significant improvement in pain and discomfort throughout the follow-up periods (p < 0.001), the changes in visual analogue scale (VAS) scores between baseline and each follow-up examination were significantly greater in the laser than the placebo group (p < 0.05). Low-level laser therapy (LLLT) before placement of resin composite could be suggested as a suitable approach to reduce postoperative sensitivity in class V restorations.

A comparative study of toluidine blue-mediated photodynamic therapy versus topical corticosteroids in the treatment of erosive-atrophic oral lichen planus: a randomized clinical controlled trial.

Recently, photodynamic therapy (PDT) has been suggested as a new treatment option that is free from side effects for erosive-atrophic oral lichen planus (OLP). The purpose of this study was to compare the effect of toluidine blue-mediated photodynamic therapy (TB-PDT) with local corticosteroids on treatment of erosive-atrophic OLP. In this randomized clinical trial, 25 patients with keratotic-atrophic-erosive oral lichen planus were allocated randomly into two groups. Group 1 (experimental): topical application of toluidine blue with micropipette was applied, and after 10 min, the patients were treated with a 630-nm GaAlAs laser (power density: 10 mW/cm(2)) during two visits. Group 2 (control) used mouthwash diluted with dexamethasone (tab 0/5 in 5 ml water) for 5 min, and then, it was spat out, and after 30 min, the mouth was rinsed with 30 drops of nystatin 100,000 units for 5 min and again spat out. Demographic data, type, and severity of the lesions and pain were recorded before and after treatment and then at the 1-month follow-up visit. Response rate was defined based on changes in intensity of the lesions and pain. In the experimental and control groups, sign scores of changes significantly reduced after treatment respectively (p = 0.021) and (p = 0.002), but between the two groups, no significant difference was observed (p = 0.72). In the experimental (p = 0.005) and control groups (p = 0.001), the intensity of lesions significantly reduced after treatment and there was a significant difference between the two groups (p = 0.001). The mean amount of improvement in pain was significantly greater in the control group compared with the experimental group (p < 0.001) (α = 0.05). Our study showed that TB-PDT with laser was effective in the management of OLP.

Comparison of the effect of low level laser therapy with alvogyl on the management of alveolar osteitis.

BACKGROUND: This study investigated the efficacy of low level laser therapy (LLLT) for managing alveolar osteitis (AO). MATERIAL AND METHODS: Sixty patients with alveolar osteitis of mandibular third molars were randomly divided into three groups. In group 1, socket irrigation was followed by alvogyl placement, and the treatment was repeated 48 hours later. In group 2, socket was irradiated with a low power red laser for 3 consecutive days (200 mW, 30 seconds on each of the buccal and lingual surfaces and 30 seconds at the middle of the socket, 6 J per area). The subjects in group 3 underwent treatment with a low power infrared laser with the same parameters as group 2. A visual analogue scale (VAS) was used to record the degree of pain at the morning (T0, before intervention) and at 6 (T1) and 12 (T2) hours later for 3 days. RESULTS: Pain was significantly lower in the alvogyl group than the other groups at T1 and T2 points on day 1 and at T0 and T1 points on day 2 (p<0.05). At T2 point on day 2 and on day 3, VAS became significantly lower in the red laser group compared to the other groups (p<0.05). The infrared laser was not more efficacious than the other groups at any of the treatment intervals, but it reduced VAS to an acceptable level. CONCLUSIONS: LLLT displayed good results in this study for treatment of alveolar osteitis and should be further investigated as an alternative to alvogyl for AO management.