Dental Hypotheses
Volume:12 Issue: 3, Jul-Sep 2021

After W.D. Miller proved a causal relationship between microbes and dental caries and periodontitis, the repair and replacement of damaged or lost teeth resulting from microbial activity dominated 20th century dental practice. In this study, I predict that in the 21st century dental practice will shift to the treatment of those dental diseases not caused by microbes. As dentists already treat some nonmicrobial diseases, I will focus on craniofacial malformations, the group of nonmicrobial diseases usually called birth defects. Some examples include dental dysplasias, cleft lip and palate, and malocclusion. In this study, I introduce the word “dysmorphogenesis”(to replace the term birth defect) as it more appropriately ascribes this subset of nonmicrobial diseases results to mistakes during the formation of craniofacial structures. As dysmorphogenic diseases occur during gestation, their diagnosis and especially their treatment require intervention during embryogenesis. Fortunately, decades of research have shown that mutations are involved in malformations during amelogenesis, palatogenesis, and odontogenesis. Knowledge of which genes are involved, together with recent breakthroughs in Crispr gene editing, make interventions during gestation possible. Those dentists performing gene editing procedures I have previously called Biodontists, because creating the Biodontics specialty will take time. The dental profession including dental educators, dental practitioners, and dental manufacturers should begin discussions now on how best to proceed.

The purpose of this review is to establish how the theory of complexity is understood and instituted in dentistry.

The stomatognathic system can be understood as a dynamic, complex, and adaptive system. Each pathological or physiological condition of this system involves physical, chemical, and biological processes in constant, open, and changing interactions with social, emotional, nutritional, political, and economic processes. Against this background, specifically, the following research questions were posed: How do researchers use complexity science in dentistry? How is complexity science described in dentistry articles?.

A brief literature search was implemented, which identified 11 PubMed articles as well as two from the Literatura Latinoamericana y del Caribe en Ciencias de la Salud (LILACS) database and one from the Cochrane Library for a full text review. Studies on complexity in the dental sciences are mostly presented in the form of critical opinion articles, which corresponded to 50% of the reviewed articles. In dentistry, complexity is understood as less of a theory and more as a line of thinking regarding procedures that can become complex at any given time.

This article shows that there are great difficulties in integrating complexity and understanding it in dentistry. There are many aspects from complexity science that still need to be understood in oral health.

Recently, toothpastes containing herbal antimicrobial ingredients have gained popularity due to their reduced side effects. This study aimed to compare the antimicrobial efficacy of two herbal toothpastes and a nonherbal type on pathogens responsible for caries and periodontal disease.

Full and 1:3 concentrations of two herbal toothpastes (Himalaya® and Herbex®) and a nonherbal type as the positive control (Crest® cavity protection) were prepared. Sterile distilled water was considered as the negative control. Streptococcus mutans, Streptococcus sobrinus, Lactobacillus casei, and Actinobacillus actinomycetemcomitans (A.a) were cultivated on agar plates and incubated after adding toothpaste preparations. The diameter of the inhibition zone was measured in millimeters. Two-way analysis of variance and Tukey Post-hoc tests were applied at P <0.05.

The mean margin diameter was higher in full concentration than the diluted 1:3 formula for all examined toothpastes (P <0.001). All three toothpaste types exerted a significant antimicrobial effect compared to the negative control (P <0.05). The antimicrobial effect of Herbex® on S. sobrinus was significantly lower than the positive control, and it was significantly less effective against S. mutans compared to Himalaya (P <0.05). Furthermore, the efficacy of Himalaya® on L. casei and A.a was significantly lower than the positive control (P <0.05). No statistically significant differences were observed in other pair comparisons.

Considering the observed efficacy of herbal toothpastes against cariogenic bacteria and periopathogens, they potentially qualify as complementary agents for self-care oral hygiene procedures.

Myofascial pain dysfunction syndrome (MPDS) can be a consequence of conditions such as temporomandibular disorders. The aim of this study was to compare the effect of diode laser and ibuprofen to reduce pain and inflammation in patients with MPDS.

In this study, 40 patients with MPDS were randomly divided into two groups. One group received ibuprofen 500 mg two times a day for 3 weeks and had placebo laser sessions. The other group received active laser (diode 810 nm CW) as treatment factor and placebo drug. Pain intensity was measured by visual analog scale and maximum painless mouth opening was also measured as a functional index every session and in a 2-month follow-up. Data were collected and analyzed using independent ttest and analysis of variance (a=0.05).

Low-level laser group showed a significant reduction in pain and a significant increase in mouth opening. In ibuprofen group, neither pain intensity nor maximum mouth opening had significant improvement.

Treatment with low-level laser improved mouth opening and pain intensity significantly in patients with MPDS. Therefore, low-level laser can be a good treatment modality for these patients.

To assess the fracture strength of repaired implant-supported cement-retained monolithic zirconia restorations with porcelain and composite resin.

Nighty monolithic zirconia crowns were cemented over the implant abutments, and divided into three groups (n =30): control, screw access hole preparation in the crown and its restoration with composite resin (HC), and screw access hole preparation in the crown and its restoration with feldspathic porcelain (HP). Fracture strength was measured by a universal testing machine. Data were analyzed (a<0.05).

The maximum fracture strength was in the control group (764.23 ± 108.41 N), whereas the minimum was in HC group (686.25 ± 101.86 N). The mean fracture strength in HC group was significantly lower than that in the control group (P =0.008). No significant difference was noted between other groups (P >0.05).

Repaired implant-supported monolithic zirconia crowns with feldspathic porcelain provided a fracture strength comparable to that in the control group.

The study evaluated the effectiveness of different tube voltages of the cone-beam computed tomography (CBCT) device on the diagnosis of vertical root fractures in teeth with single root canals and posts.

Sixty single-canal and single-rooted extracted human mandibular premolars were selected, all of which were intact and contained no fractures. After disinfection, teeth crowns were sectioned and teeth canals were prepped and obturated by a method similar to the rotary technique. Root fractures were created in half of the teeth by applying controlled buccolingual force. Prefabricated metal posts were subsequently placed in all teeth using AH26 sealer. All teeth, both intact and fractured, were mounted in bovine ribs and X-rayed randomly using a CBCT device (Planmeca Romexis, Helsinki, Finland) with three tube voltages (min =66 kVp, mid =80 kVp, and max =92 kVp). Three experienced maxillofacial radiologists observed and commented on the images. Research data were analyzed using SPSS-25 software.

Images taken by kVp min were removed from further statistical analysis due to a lack of diagnostic information. For mid (80) and max kVp (92), the sensitivity values were 86.6% and 60 % (P=0.04), and the specificity values were 33.3% and 30%, respectively (P=0.45). Overall, observers’opinions were more alike concerning images taken with kVp mid than kVp max.

Apparently, images taken by a tube voltage of 80 kVp are more efficient in the diagnosis of root fractures.

This research was carried out to compare the effects of 0.525% and 5.25% NaOCl, 2% H2O2, and 16-mg/mL propolis on additional silicone impression materials contaminated with Candida albicans at 5- and 10-minute exposure times, to evaluate the hypotheses of this study that propolis can be used for disinfecting of dental impressions.

A total of 122 silicone impressions were prepared. Two samples were considered the negative controls, and the rest were contaminated with C. albicans fungal species and disinfected with 0.525% NaOCl, 5.25% NaOCl, 2% H2O2, 16-mg/mL propolis, and 96% ethyl alcohol for 5 and 10 minutes (10 samples for each interval in each group). The data were analyzed with Kruskal–Wallis and Mann–Whitney U tests in all the groups at 5- and 10-minute intervals.

All the disinfecting agents significantly decreased C. albicans colony counts at both intervals compared to the control groups (P =0.00). The differences in the disinfecting effects were significant between the four study groups (P =0.00). The most significant effects were related to NaOCl at both intervals and concentrations and 2% H2O2 at the 10-minute interval (P =0.001), followed by 2% H2O2 at the 5-minute interval and propolis (P =0.001). Concerning propolis (P =0.001) and 2% H2O2 (P =0.004), the effect of exposure time was significant.

All the disinfecting agents in the present study can be used to disinfect impressions contaminated with C. albicans; however, concerning propolis, although it resulted in significant decreases in C. albicans colony counts, the elimination of the remaining colonies was ineffective.

Dental students’confidence is a crucial factor affecting the success of endodontic teaching. The aim of this study was to determine the dental students’confidence level in performing endodontic treatment.

A total of 150 dental students of Isfahan University of Medical Sciences participated in this descriptive study by census sampling. A self-administered questionnaire, including demographic data, endodontic experience, confidence in performing different stages of endodontic treatment, and suggestions for improving the quality of endodontic training, was distributed among the fourth to sixth year students. Data were analyzed with SPSS version 20.0 (IBM Corp., Armonk, New York, USA), using ttest, ANOVA, and linear regression analysis (a=0.05).

The response rate was approximately 88%, and the highest and lowest confidence scores (standard deviation) were reported for establishing proper communication with patients with 4.0 (34.67) and finding all root canals with 3.0 (23.88). The confidence score of male students was significantly higher than female students (P<0.05). There was no significant association between the total score of confidence and difficulty level of the first endodontic treatment and educational level (P>0.05). The multiple linear regression showed a significant correlation between the difficulty level of the first endodontic treatment and confidence (b=−2.1, P=0.02, 95% CI: −3.9–−0.2).

Given the low confidence level of students in some skills, the following are suggested to be taught practically and theoretically. Female students should be provided with a technique to improve confidence. Moreover, the first tooth for endodontic treatment should be selected more thoughtfully.

The key for long-term success in root canal therapy is the effective debridement with chemical irrigants before obturation. The purpose of this study was to compare the antimicrobial effect of sodium hypochlorite and chlorhexidine along with activation using sonic and an ultrasonic device in teeth when used in teeth infected with Enterococcus faecalis.

A total of 90 single rooted mandibular premolar were infected with E. faecalis and placed in the incubator for 24 hours .The specimens were divided into six groups as follows: Group I: positive control; Group II: negative control; Group III: sodium hypochlorite + passive ultrasonic activation for 20, 40, and 60 seconds; Group IV: chlorhexidine + passive ultrasonic activation; Group V: sodium hypochlorite + endoactivator; and Group VI: chlorhexidine + endoactivator activation. After disinfection, dentinal shavings were collected using H file and subcultured in brain heart infusion agar (BHI) broth further streaked in brain heart agar plates to check the colony counting.

Bonferroni post hoc test was done to compare the significant difference between different experimental groups. Group III showed a significant difference in the antimicrobial activity compared to Group IV, V, and VI with P <0.05. One-way analysis of variance (ANOVA) analysis was done to analyze the intergroup comparison of the bacterial count at various time intervals (20, 40, and 60 seconds). It was observed that there was a statistically significant difference with P <0.01 between the time interval of different experimental groups.

Within the limitation of this study, sodium hypochlorite along with passive ultrasonic irrigation showed a reduction in E. faecalis count compared to the other irrigating protocols used in the study and the results were statistically significant.

The objective of the present study was to evaluate and compare the bond strength of orthodontic brackets bonded to permanent teeth with a conventional acid-etching and self-etching primer systems. Also, the study aims to evaluate the mode of bond failure after debonding the brackets.

It was an experimental study. Fifty extracted permanent premolars were collected, checked, and cleaned. Teeth were split equally into two groups, group A and B. Orthodontic brackets were bonded using conventional acid-etching and self-etching primer systems for group A and B, respectively. Shear bond strength (SBS) was measured with a universal testing machine, and the mode of bracket-adhesive failure was determined by using adhesive remnant index (ARI). Data were analyzed with a statistical software. Independent sample t-test was used to compare the SBS and Mann–Whitney U test was used to assess whether there is a significant difference of ARI score between the groups.

Although the SBS with self-etching primer was within clinically acceptable range, the overall mean SBS for group A (14.71 MPa) was significantly greater than group B (9.24 MPa) (P =0.024). There was no significant difference in ARI scores between conventional acid-etching and self-etching groups (P =0.801).

The SBS of the conventional acid-etching was significantly higher than the self-etching primer. The SBS of self-etch was within the acceptable range to withstand the forces of mastication. The majority of the brackets recorded ARI score of 1 indicating a cohesive failure with no significant difference between acid-etch and self- etch groups.

The dental clinic has for a long time been considered as a risky place for infection dissemination. Due to aerosol generating procedures, the risk of cross-transmission in dental clinics has recently risen. Open dental clinics should undergo present-time reassessment concerning infection control, in particular, to consider the implications of the SARS-CoV-2 pandemic for today’s advanced technological and medical practices. It might be necessary to make urgent and appropriate modifications to the design of air circulation systems in the dental environment to prevent microbial transmission.

In order to minimise cross-transmission in multi-chair dental operatories, we have designed two model ventilation systems with 12 and 36 air change/hour capacities and with laminar airflow direction. The conditioned air directly blows into the dental treatment units, especially into the aerosol generating area, where the contamination is more concentrated. We hypothesise that these new designs could serve to isolate dental treatment units to function separately like closed dental operatories while keeping them open to each other.

Thorough physical and biological investigations will be required to determine how these designs can be applied effectively in terms of the required spatial separation of dental treatment units in the open multi- chair dental operatories.