Dental Research Journal
Volume:17 Issue: 6, Nov-Dec 2020

In December 2019, a series of unusual pneumonia has been reported in Wuhan, China. This pneumonia was related to beta‑coronavirus cluster which was named COVID‑19. The aim of this study is to review the published paper on COVID‑19 protections guide lines and attempt to summarize different suggested guide lines in order to help dental/oral healthcare to have better protection against COVID ‑19

An electronic literature search was conducted via google scholar, PubMed, and dental associations’ of different countries’ website using the key word “COVID‑19, Dental team, Guide lines and Recommendation”.A total of seven guidelines were found suitable to be included in this review.

Individuals with ‘possible’ or ‘confirmed’ COVID‑19 should not be seen for routine dental care. Multi‑step approach should begin before the patient arrives on the office and includes guidance regarding their arrival and it should be completed duration of the affected patient’s presence in the practice. Accurate travel history, fever or history of fever, acute respiratory infection and severe respiratory infection without fever requiring hospitalization should be checked by staff via patients telephoning to make an appointment and finally the primary infection control goal is to prevent transmission of disease. These treatment guidelines are based on very limited evidence from the literature and should be revised as soon as more evidence about the infection control advices for dental team regarding COVID‑19.

The aim of this study was to assess the fracture resistance of pulpotomized primary molars restored with incremental and bulk‑fill composite application techniques.

In this in‑vitro experimental study, 36 extracted primary molars were nonrandomly (selectively) divided into three groups of 12 each. All teeth underwent conventional pulpotomy treatment, and mesio‑occluso‑distal cavities were prepared in such a way that the buccolingual width of the preparation was two‑thirds of the intercuspal distance, and the depth of the buccal and lingual walls was 4 mm. The teeth were then restored as follows: Group 1 (control) was restored with amalgam, Group 2 was restored with Tetric N‑Ceram composite using the incremental technique, and Group 3 was restored with Tetric N‑Ceram composite using the bulk‑fill technique. The restored teeth were subjected to thermocycling and then underwent fracture resistance testing in a universal testing machine at a crosshead speed of 1 mm/min. Fracture resistance of groups was compared using the one‑way ANOVA and Tukey’s honestly significant difference test.

The mean fracture resistance was 1291.47 ± 603.88 N in the amalgam, 1283.08 ± 594.57 N in the Tetric N‑Ceram incremental, and 1939.06 ± 134.47 N in the Tetric N‑Ceram bulk‑fill group. The difference in this regard between Group 3 and Groups 1 and 2 was statistically significant (P = 0.019 and P = 0.035, respectively).

Bulk‑fill composite is recommended for reinforcing the remaining tooth structure after the primary molar pulpotomy procedure. Time‑saving characteristics of this material are clinically important for reducing appointment time for children.

Endodontically treated teeth with extensive structural damage present higher fragility due to the low amount and worse quality of the reminiscent tissues of the crown.

The present in vitro study evaluated the effect of different intraradicular retainers and cementation agents on the fracture resistance of devitalized teeth. Incisive teeth (n = 40) of bovine mandibles were used. After preparation of the root canals, they were immersed in polyether, in a polyvinyl chloride cylinder containing acrylic resin, to simulate the periodontal ligament. The specimens were randomly divided into four groups (n = 10), according to the type of retainer (anatomical or main with accessory posts) and resin cement used (conventional resin cement – RelyX ARC or self‑adhesive resin cement – RelyX U200). The specimens were stored in distilled water at 37°C and submitted to fracture resistance testing. ANOVA and Tukey’s test were applied for data analysis, with significance level set at 5%.

There was no interaction between cement type and intraradicular retainers (P = 0.56) or even between the types of cement used (P = 0.65). However, in the variation of the types of retainers, the group using main with accessory posts presented greater resistance to the fracture than the anatomical post (P = 0.04).

Different cementing agents have no effect on the fracture strength of devitalized teeth, unlike the use of posts, in which the use of accessory post proved more resistant when compared to the anatomical post.

Dentin‑bonding agents should have good biocompatibility as they come into close and prolonged contact with vital dentin. The present study aimed to evaluate and compare the cytotoxicity of total etch and self‑etch dentin bonding systems with two different dentin thickness on L929 cell line.

In this in vitro study 80 Class I cavities were prepared on the occlusal surfaces. The teeth were randomly divided to two groups of 40 each based on two RDT 0.5 mm and 1.5 mm. Samples were further subdivided into four subgroups of 10. Group 1: Adper Scotch bond Multi-Purpose (SBMP), Group 2: Adper Single Bond Plus (SBP), Group 3: Adper Scotch bond SE (SSE) and Group 4: Adper Easy One (EO). Group 1 and 2 were total-etch and Group 3 and 4 were self-etch. The cavities were sealed after applying of dentin bonding. Then crowns were immersed in culture medium for 24 hours and the cytotoxicity of resultant toxic extraction was measured with 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in 4 serial dilutions (neat,1/2 ,1/10 ,1/100). Data were analyzed by Two-way ANOVA and t-test.

For all the dilutions, cytotoxicity was significantly higher with 0.5 mm remaining dentin thickness (RDT) relative to 1.5 mm RDT (P ≤ 0.05). In neat dilution for both RDTs, cytotoxicity was different among all the four dentin bondings. Expression in decreasing order of cytotoxicity was SBP > SBMP > SSE > EO for both RDTs in neat dilution (P < 0.05). For all the dilutions, cytotoxicity was significantly lower for self‑etch bonding systems in comparison with total‑etch bonding systems (P < 0.05).

In the present study, lower cytotoxicity was found with an increase in the dilution of toxic extract and also cytotoxicity decreased with an increased dentin thickness. The adhesive systems had degrees of cytotoxic effects on cultured L929 compared to the control, except for the EO group.

Given the importance of primary dental caries, assessment of new preventive/ therapeutic materials is necessary. In light of the scarcity of such studies on the role of new agents in primary dentition, this study assessed the efficacy of three commercial toothpastes with different ingredients on remineralization of early caries in the primary dentition.

Thirty‑nine intact primary canines were used in this in vitro experimental study. The baseline microhardness of enamel was measured. Particular demineralizer was used for 96 h and then secondary microhardness was measured. Then, samples were divided into three groups treated by toothpastes with sodium fluoride, chitosan, and casein phosphopeptide‑amorphous calcium phosphate and sodium monofluorophosphate (CPP‑ACP+SMFP). Each group was incubated and pH‑cycled. Subsequently, they were demineralized and remineralized using toothpastes. Eventually, tertiary microhardness was measured. Percent of enamel microhardness recovery (EMHR%) and efficacy of toothpastes in remineralization were established. Data were analyzed using paired t‑test, repeated‑measures test, Kruskal–Wallis, and Mann–Whitney U‑test (α = 0.05, 0.017).

Demineralization significantly reduced microhardness from 316.2 to 248.5 Vickers hardness number (VHN) (P = 0.000). All toothpastes succeeded to remineralize the enamel significantly (P = 0.000). The efficacies of toothpastes differed significantly (P < 0.05). Mean EMHR percentages of toothpastes incorporating NaF, chitosan, and CPP‑ACP+SMFP were 75.1%, 52.5%, and 55.8%, respectively. The highest increases in enamel microhardness were observed after using NaF‑containing toothpaste (~53 VHN) which was significantly superior to other toothpastes (P ≤ 0.001). However, there was no statistically significant difference between EMHR percentages of toothpastes including chitosan and CPP‑ACP+SMFP (P = 0.739).

Although all three toothpastes could increase the microhardness of primary enamel, NaF toothpaste was superior to others. Toothpastes having chitosan and CPP‑ACP+SMFP acted rather similarly.

High percentage of biomechanical complications such as screw loosening in dental implants can be related to implant–abutment (I/A) connection properties which affect the behavior of implant assembly against functional loads in the oral cavity. The aims of the present study were to compare the reverse torque values (RTVs) and failure loads of three abutment types with internal Morse taper connection.

In this experimental in vitro study, eighteen implants (4.5 mm × 10 mm bone level implants, Implantium, Dentium Co, Seoul, South Korea) were divided into three groups with different abutments: two‑piece (TP) abutment, one‑piece (OP) abutment, and screw abutment (SA), mounted in stainless‑steel blocks according to ISO 14801. After completion the torque/detorque protocol, a compressive load (1 mm/min) was applied at 30° off‑axis until failure. Mean reverse torque/tightening torque (RT/TT) values and failure loads were analyzed with one‑way ANOVA test and Tukey’s honest significant difference (α = 0.05). Failure modes were evaluated by radiography and stereomicroscopy.

RT/TT values in the TP group were lower than those in other groups (P < 0.001). Highest failure loads were observed in SA group (P = 0.002). In radiographic evaluation, all specimens showed deformation in I/A interface.

I/A connections with larger surface areas may lead to higher RTVs (e.g., OP and SA groups). Use of an additional screw and indexed area in TP group did not reduce the bending resistance under static loading.

The aim of this study was to assess the discoloration of coronal tooth structure irrigated with different irrigation solutions and filled with calcium silicate‑based materials containing bismuth oxide or calciumzirconia complex as radiopacifier.

In this ex vivo study, 72 bovine enamel‑dentin blocks were prepared and divided into three groups. The dentinal cavities in each group were irrigated with 5.25% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX), or normal saline for 30 min. After that, irrigation solutions were removed using a cotton pellet. Each group was then randomly divided into two subgroups according to the cavity‑filling materials (ProRoot mineral trioxide aggregate [MTA] and RetroMTA). The color assessments were performed before filling the cavities and 1 month and 6 months after filling the cavities. Data were analyzed with two‑way ANOVA. The level of statistical significance was set at P < 0.05.

The effect of irrigation solution on the color change of calcium silicate‑based materials was not statistically significant at none of the time intervals (P = 0.334 and P = 0.252, respectively, for ProRoot MTA and RetroMTA). ProRoot MTA caused a significantly higher color change compared with RetroMTA exposed to different irrigation solutions at each time interval (P < 0.001). Color change of both materials exposed to each irrigation solution significantly increased over time (P < 0.05).

Under the condition of this ex vivo study, irrigation of dentin with NaOCl and CHX and then removing the excess solution might be ineffective in increasing the tooth color change potential of either bismuth oxide or zirconium‑containing calcium silicate‑based materials. Furthermore, calcium silicate‑based material, which contained bismuth oxide, caused higher tooth discoloration.

The aim of this study was to compare conventional and microwave‑assisted decalcification of sheep bone with and without teeth and to detect any difference in tissue detail preservation, staining quality, and rate of decalcification.

In this method analysis study, twenty‑four specimens consisting of 12 blocks of mandibular molars with their surrounding bone and 12 blocks of mandibular osseous tissue were allocated into two microwave or routine decalcification groups using 5% nitric or formic acid as decalcifying agents. In addition to decalcification rate, a number of variables were used to assess staining quality and tissue detail preservation which were compared between the two groups using Mann–Whitney test (P < 0.05).

Time to complete decalcification was significantly reduced in the microwave‑treated samples as compared to the conventional method, regardless of the decalcifying agent (P = 0.025). For both acids, most variables related to staining quality and tissue detail preservation were similar between the techniques (P > 0.05). Patchy staining in bone samples and tissue tears in bone + teeth specimens were more common in the routine method when using nitric acid (NAc) (P = 0.046) and formic acid (FAc) (P = 0.046), respectively. In comparing acids, the performance of FAc was slightly inferior to that of NAc, especially for specimens containing both tooth and bone.

The use of microwave technology can accelerate decalcification of bone and teeth of sheep mandibles and at the same time preserve tissue structure and staining quality. Further studies are required to help select the best demineralizing agent, especially in specimens containing bone and teeth.

This study aimed to evaluate the relationship of the level of salivary peptides human neutrophil defensin (HNP) 1–3 in children with and without early childhood caries (ECC).

This in vitro study was conducted among 86 children of age 3–6 years who were divided into two groups: Group 1 – children with ECC (n = 43) and Group 2 – children without ECC (n = 43). Saliva samples were collected, and salivary peptide HNP1–3 levels were analyzed using enzyme‑linked immunosorbent assay. The data collected were subjected to appropriate statistical analysis. Independent sample t‑test was used to compare the mean salivary peptide levels of HNP1–3 in children with and without ECC. One‑way ANOVA was used for intragroup comparison of the mean peptide levels between the ages. P < 0.05 was considered statistically significant.

The mean age of the children in Group 1 and Group 2 was 5.12 ± 0.851 and 4.88 ± 0.879 years, respectively. A statistically significant decrease was seen in salivary peptide HNP1–3 levels in children with ECC (1.44 ng/ml) when compared to children without ECC (6.04 ng/ml) with P < 0.001. There were no statistically significant differences in the gender‑ and age‑based comparisons.

A decrease in salivary peptide HNP1–3 levels might be a biological factor for predisposition to ECC and hence can be used as a predictive and a preventive tool in caries prevention.

A longitudinal study design was conducted to assess the mandibular cortical shape index (CI) in panoramic radiographs retrospectively. An association between age and a deterioration of different radiological parameters on panoramic radiographs was stated in cross‑sectional studies. As longitudinal studies are rare, this one is designed to assess radiological changes over time.

In this longitudinal study, The archive of the dentomaxillofacial radiology department was searched for panoramic radiographs of patients who have two radiographs with a time lapse of at least 15 years between both. The radiographs were then examined and the CI was categorized into three categories: normal, mild, and severely eroded. The following factors were examined to determine if they had an effect on possible changes of the CI using the Chi‑square test:The time period between both radiographs, the gender and the age of the subjects when both radiographs were made also compared using the Kolmogorov–Smirnov test.

Ninety radiographs met the inclusion criteria. The mean age, when the 1st radiograph and the 2nd radiograph were made, was 48.7 and 66.9 years, respectively. A deterioration of the CI over time was observed and only 31.1% of the radiographs remained in the same CI category while 57.8% dropped down by one category and 11.1% dropped down by two. The change of CI was significant (P < 0.001 using the McNemar’s test).

In this longitudinally designed study, a deterioration of the CI over time when assessing the nonstandardized panoramic radiographs could be confirmed. This study shows that 68.9% of the patients had CI deterioration of at least one category over the average time of 17.96 years. This is the first study to quantify the CI deterioration over time to our knowledge.

Oral pathology, a branch of dentistry which is often termed as a nonclinical branch deserves a better description as fundamental knowledge of oral pathology is essential to become a successful dental clinician. This study was conducted to analyze the approach toward Oral Pathology and Histology as a subject and profession among dental undergraduates.

A questionnaire‑based, cross‑sectional study was conducted among 200 students which included the 3rd year, 4th year and interns studying in a Dental College in Gurugram, Haryana. The questionnaire comprised 14 close‑ended questions, divided under three parameters which included demographic characteristics, students’ perception about the Oral Pathology and Histology as a subject, and willingness to choose it as a career option. The data recorded was subjected to statistical analysis using the Chi‑square test. The level of statistical significance was set at P ≤ 0.05.

Among all the participants, 53 (26.5%) were males and 147 (73.5%) were females. It was found that 33.5% of the total students find the subject interesting, but 24.5% students reported their main focus on just passing this subject. Although they reported liking toward the subject, majority of them (64%) did not express their interest to pursue it as their postgraduation specialty.

The present scenario of Oral Pathology and Histology as a subject is alarming and in that scenario it should be our prime concern to change the attitude of students toward the subject who perceive it as a nonclinical subject having a lesser scope for practice with a need to broaden the scope of the specialty and to make it more practical.

Tricho–dento–osseous (TDO) syndrome is a multisystem congenital disorder that is known by bone, skin, and hair abnormalities. Primitive studies show different varieties of manifestations related to this disorder, which involve sclerotic bones, nail involvement, enamel hypoplasia, mandibular prognathism, and taurodontism. Although exploring different TDO cases revealed genetic mutations in all of them, they have many variations in phenotypic view. In this study, we report a case whose primary diagnosis was alopecia and came for extraction of her third molars, but after clinical and radiographic examination, it was found that the cause of her disease was something different.