Journal of Dental Research, Dental Clinics, Dental Prospects
Volume:15 Issue: 2, Spring 2021

This study aimed to evaluate the effects of repeated sterilization cycles on the surface alterations of various nickel-titanium instruments, including ProTaper Next (PTN), TF Adaptive (TFA), HyFlex CM (HCM), and 2Shape (2S).

Twenty-four new NiTi files of four different alloys were selected. The instruments in each group were divided into two equal groups, as follows: control and sterilization. The first group was chosen as the control without applying any sterilization procedure, while in group 2, five cycles of sterilization procedures were applied. The surface topographies were evaluated using scanning electron microscope (SEM) and atomic force microscope (AFM). The root mean square (RMS) and maximum height (MH) values and three-dimensional images were recorded. The data were analyzed with the Shapiro-Wilk test, one-way ANOVA, and post hoc Tukey tests. The statistical significance level was set at P≤0.05.

Before the experiment, HCM demonstrated the highest RMS value, and 2S showed the lowest. After the procedures, the RMS and MH values deteriorated on the surface of PTX, TFA, and 2S (P<0.001). The HCM was not affected by sterilization processes (P>0.05).

The initial irregularity on the surface did not affect the rate of alteration. The HCM files demonstrated superior surface properties after several cycles of sterilization. The PTN, TFA, and 2S presented similar surface responses after five cycles of autoclave sterilization.

Contamination of dentin surface is one of the common problems in restorative dentistry. The aim was to investigate the effects of different surface contaminators on the dentin shear bond strength (SBS) of universal adhesive system (UAS) applied in etch-and-rinse (ER) and self-etch (SE) strategies.

One hundred forty-four maxillary anterior sound human teeth were divided into six groups based on the types of surface contaminators: no surface contaminator (control) and experimental groups contaminated with blood, saliva, aluminium chloride (ALC), ferric sulphate (FS), and caries disclosing agent (CDA). Then, each group was further subdivided into two, based on the application strategy of UAS (ER and SE). After applying the adhesive according to the manufacturer’s instructions, and bonding cylindrical composite samples, the SBS was measured. The data were analysed using two-way ANOVA, Tukey’s HSD test and t test (P<0.05).

The SBS in all contaminated groups, except for CDA, was significantly lower in both ER and SE strategies compared to control group (P<0.05). A comparison between the application strategies revealed that ER and SE were only significantly different in the FS contaminated group (P<0.05).

All tested contaminators, except CDA, significantly decreased SBS of UAS in both ER and SE strategies.

The present study evaluated the antimicrobial efficacy of composite resins containing nano-silver (NAg) particles used in fixed orthodontic retainers.

Nano-composite resin samples with 1%, 2%, and 5% concentrations of NAg were prepared. The antimicrobial effectiveness of NAg was assessed against Streptococcus mutans, Streptococcus sanguis, and Lactobacillus acidophilus by the biofilm inhibition test (three-dayold biofilms), eluted components test (on days 3, 15, and 30), and disk-diffusion agar test after 48 hours. Measures of central tendency and index of dispersion were used to determine colonyforming units. Kruskal-Wallis test and Mann-Whitney U test were also used.

The biofilm inhibition test showed a significant decrease in the colonies of S. mutans (87.64%, 96.47%, and 99.76% decrease), S. sanguis (98.13%, 99.47%, and 99.93% decrease), and L. acidophilus (81.59%, 90.90%, and 99.61% decrease) at 1%, 2%, and 5% concentrations of Nag, respectively, compared to the control groups. The colony-forming unit (CFU)/mL of tested microorganisms continuously decreased with increased NAg concentration. In the eluted component test, no significant differences were noted in the 3rd, 15th, and 30th days between the different concentrations of Nag-containing composite resin disks and control samples. According to the disk-diffusion agar test, there was no growth inhibition zone for the composite resin disks containing 1% and 2% concentrations of Nag. However, the growth inhibition zone was seen with a 5% concentration, with a diameter of 9.5±0.71 mm for S. mutans, 8.5±0.71 mm for S. sanguis, and 8±1.41 for L. acidophilus.

The incorporation of NAg into composite resins has antibacterial effects, possibly preventing dental caries around fixed orthodontic retainers.

The potent anti-inflammatory and immunosuppressive properties of glucocorticoids (GCs) might influence the progression of some disorders, such as periodontitis. Hence, this study aimed to investigate the influence of dexamethasone (DEX) on the alveolar bone loss (ABL) of healthy and periodontally compromised molars in rats.

Thirty male rats were randomly assigned to two groups: physiological saline solution (PSS) and DEX. The animals received subcutaneous injections of either 0.5 mL of PSS) (group PSS) or 2 mg/kg of DEX (group DEX) from one day before experimental periodontitis (EP) induction until euthanasia. EP was induced through ligature placement around the mandibular lower first molars at day 0. Contralateral molars remained unligated. Ten animals per period were euthanized on days 3, 7, and 14. Morphometric analysis was performed to access the ABL. Data were statistically analyzed with ANOVA followed by post hoc Tukey tests (P≤0.05).

Higher ABL was observed in both groups on days 7 and 14 than on day 3 (P≤0.05). Concerning periodontitis, higher ABL was observed in group DEX on days 3, 7, and 14 days than group PSS at the same time intervals (P≤0.05). Also, even in the contralateral unligated molars, group DEX exhibited higher ABL on days 3, 7, and 14 days than group PSS at the same time intervals (P≤0.05).

Collectively, it can be concluded that DEX aggravates EP and induces spontaneous ABL in the healthy periodontium.

This study aimed to evaluate the incidence and severity of orthodontically induced inflammatory external apical root resorption (OIIEARR) and the relationship between OIIEARR and possible risk factors such as orthodontic treatment type, treatment duration, gender, and age of the patients. A further aim was to determine the prevalence of OIIEARR in different tooth groups.

The study sample consisted of 1356 orthodontically treated patients (857 females and 498 males; mean age: 14.4±2.8 years). OIIEARR was evaluated using pre- and post-treatment panoramic radiographs for all the tooth groups. Teeth with severe resorption were also assessed. Patient- and treatment-related risk factors for OIIEARR were assessed statistically using Pearson’s chi-squared test, independent-samples t test, and one-way ANOVA.

The incidence of severe root resorption following orthodontic treatment was 14.8%. Males exhibited a higher incidence of root resorption compared to females. Orthodontic treatment duration and treatment with extractions were positively correlated with OIIEARR (P<0.05). OIIEARR was observed most frequently in maxillary incisors, followed by mandibular incisors.

Orthodontic treatment with extraction, prolonged treatment duration, and large movements of the incisors should especially be taken into consideration for OIIEARR risk. Routine radiographic follow-up during orthodontic treatment is recommended.

Maxillary bone atrophy with a considerable amount of pneumatization and anterior expansion of the maxillary sinus might be a situation limiting oral rehabilitation with osseointegrated implants. Therefore, the present study aimed to biomechanically evaluate two rehabilitation techniques for maxillary bone atrophy: all-on-four and long trans-sinus implants.

Two three-dimensional models consisting of atrophic maxilla with four implants were simulated. In the M1 model, two axially inserted anterior implants and two tilted implants, 15 mm in length, placed tangential to the maxillary sinus’s anterior wall were used. In the M2 model, two axially inserted anterior implants and two trans-sinus tilted implants, 24 mm in length, were used. For the finite element analysis (FEA), an axial load of 100 N was applied on the entire extension of the prosthesis, simulating a rehabilitation with immediate loading. The peri-implant bone and the infrastructure were analyzed according to the Mohr-Coulomb and Rankine criteria, respectively.

Results:

The results were similar when the stresses on peri-implant bone were compared: 0.139 and 0.149 for models 1 and 2, respectively. The tension values were lower in the model with trans-sinus implants (27.99 MPa).

It was concluded that the two techniques exhibited similar biomechanical behavior, suggesting that the use of long trans-sinus implants could be a new option for atrophic maxilla rehabilitation.

Regenerative endodontic treatment (RET) is a clinically advanced procedure for necrotic immature teeth. However, root canal walls of these teeth are brittle especially in the cervical region and need reinforcement. This in vitro study is conducted to evaluate the effect of intra-orifice barrier materials on the fracture resistance of immature teeth treated with regenerative procedure.

Forty-eight maxillary central incisors were used. Twelve intact teeth were selected for the control group. Remained teeth were prepared using peeso drills to simulate immature teeth and assigned into three groups according to the intra-orifice barrier material placed over MTA (n=12); Composite resin (CR), ProRoot MTA and Resin-modified glass ionomer cement (RMGIC). Fracture strength test was applied using a universal testing machine. One-way ANOVA and Tukey post hoc tests were used at P=0.05.

A significant difference was obtained among groups (P<0.05). MTA showed the lowest fracture resistance (P<0.05). However, no significant difference was found among RMGIC, CR, and control groups (P>0.05).

Intra-orifice restorative materials have reinforcement affect in immature teeth treated with regenerative endodontic procedure. RMGIC or CR can be regarded as a viable choice to reduce the occurrence of cervical root fracture of immature teeth treated with a regenerative therapy.

The replacement of missing teeth utilizing dental implants and digital dental technologies has gained significant popularity in daily clinical practice over the last decade. Partially dentate patients present more anatomical references to guide the implant position and prosthetic reconstruction as compared to completely edentulous arches. Therefore, the management of edentulous maxilla using implant digital dentistry represents a challenging clinical situation where a thorough treatment plan is paramount to achieve a final prosthetic result that meets both functional and esthetic requirements. This case report discusses the oral rehabilitation of an edentulous maxilla and partially dentate mandible using a digital workflow for both the surgical and prosthetic phases of the implant therapy. Protocols for clinical assessment, treatment planning, and restorative management are described to provide a predictable and prostheticdriven treatment for implant-supported prostheses.

The present study aimed to assess the effect of botulinum toxin type A (BTX-A) for the management of gummy smile and evaluate its stability after administrating BTX-A clinically and using electromyography.

The investigators designed and implemented a prospective clinical study on 10 patients with a gummy smile. Patients with different types of gummy smile were injected with BTX-A in the levator muscles of the upper lip and were followed for six months. The effect of BTX-A was evaluated clinically and using electromyography preoperatively and after two weeks and three and six months. Statistical analyses were carried out using repeated measures ANOVA and post hoc Bonferroni tests for pairwise comparisons.

The sample consisted of 10 patients with an anterior gummy smile (n=3), posterior gummy smile (n=2), mixed gummy smile (n=3), and asymmetrical gummy smile (n=2). There were significant differences (P<0.001) between the mean gingival display and compound muscle action potential at two-weeks and three-month follow-ups. The maximum result was obtained at the two-week interval. The mean gingival display and C-MAP values increased slightly at the three-month postoperative interval and gradually increased to the baseline values at six-month follow-up.

BTX-A is an effective, minimally invasive, and temporary treatment modality for gummy smiles. The electromyographic study is a convenient method for assessing changes in the upper lip muscle contractility to quantify the effect of BTX-A in the treatment of gummy smile.

Calcium-enriched mixture (CEM) cement has been introduced and marketed as a biomaterial for use in furcal perforation repair and apexogenesis procedures, in which the compressive strength that indicates the material’s resistance against crushing is of utmost importance. This study evaluated the effect of various liquid-to-powder ratios on CEM cement’s compressive strength.

One gram of the cement was mixed with 0.5, 0.34, and 0.25 mL of demineralized water and transferred to stainless steel molds (6 and 4 mm in height and diameter, respectively). Five cells in the mold were considered for each group. The compressive strength test was conducted using the universal testing machine after incubating for seven days under 95% humidity at 37°C. One-way ANOVA was applied for data analysis at P≤0.05 significance level.

The mean compressive strength in the liquid-to-powder ratios of 0.5, 0.34, and 0.25 were 3.4456, 3.2960, and 3.3485, respectively, with no significant differences between them.

Under this study’s limitations, changing the liquid-to-powder ratio did not affect CEM cement’s compressive strength.

The present randomized clinical trial aimed to determine the additive clinical and microbiological benefits of diode laser (DL) with modified Widman flap (MWF) to manage chronic periodontitis.

Seventy-two sites in 36 healthy non-smoking patients diagnosed with chronic periodontitis were randomly assigned to the test group (MWF + active DL) or control group (MWF + sham DL). Clinical (probing pocket depth [PPD], clinical attachment level [CAL]) and microbiological (colony-forming units [CFUs]) measurements were recorded at baseline and 6- and 6-month postoperative intervals.

Compared to baseline, 6-month results showed significant changes in clinical and microbiological parameters in both groups. However, the intergroup comparison revealed significantly lower PPD (1.90±0.48 mm vs. 2.35±0.41 mm), CAL (4.43±0.57 mm vs. 4.93±0.58 mm), and CFUs for Porphyromonas gingivalis (6.32±0.18 vs. 8.88 ±1.88), Prevotella intermedia (7.62±1.86 vs. 8.12±1.78), and Aggregatibacter actinomycetemcomitans (6.43±1.44 vs. 7.24±1.22) in the test group after six months.

Within the limitations, the present study confirmed the useful role of DL with MWF to manage chronic periodontitis.

 This study aimed to evaluate and compare changes in the mandibular trabecular bone pattern using the fractal dimension (FD) and lacunarity analysis in tobacco users with healthy controls.

 This study was carried out on digital panoramic radiographs of 225 subjects divided into three groups: smokeless tobacco users (SLTs), smokers, and control (n=75). ImageJ program with FracLac plugin was used to assess the FD and lacunarity of mandibular trabecular bone on the digital panoramic radiographs.

The differences in the mean FD values of the study and control groups were statistically significant (P<0.001). Mean FD was lower in the case groups than the control group, with SLTs having the least FD value. A significant difference in lacunarity was noted between SLTs and controls (P<0.001). On the contrary, there was no significant difference in lacunarity between smokers and controls.

FD values were lower in tobacco users, suggesting that tobacco users have a less complex trabecular bone pattern than healthy controls. Higher lacunarity values in SLTs indicated a more heterogeneous bone pattern. These findings signify that FD and lacunarity analysis on digital panoramic radiographs can serve as promising predictive tools to assess bone quality for osteoporotic changes in tobacco users, thereby facilitating prompt referral for further management.