Avicenna Journal of Dental Research
Volume:13 Issue: 2, Jun 2021

Background: Palatal expansion is one of the most common types of orthodontic treatment, which is administered employing different appliances, and is used for the correction of posterior cross bite. This treatment can elevate the palatal cusp on the maxillary first molar, lead to the rotation of mandible, and increase the height of the lower third of the face. In some cases, the use of bite plane is suggested to avoid vertical dimension changes of the face. This study aimed to assess the effect of removable maxillary expanders on facial vertical dimensions. Methods: In this cross-sectional study, 68 patients referring to Hamedan School of Dentistry and being treated using removable maxillary expander with or without bite plane were examined. Pretreatment and post treatment cephalograms of the patients were analyzed by Dolphin Imaging Software 11.9 version, and the results from 5 cephalometric variables, namely the mandibular plane related to SN line, the angle of mandibular plane related to FH, Y axis, the maxillary plane angulation, as well as the lower facial height were calculated. Patient’s transverse dimension was measured by a caliper on the dental casts along the mesiobuccal cusp of maxillary first molars. Paired t test and independent t-test were adopted for carrying out data analysis. Results: There was no significant difference between the two groups in terms of age and sex at the beginning of treatment. However, maxillary plane angulation and Y axis changed significantly in group with bite plane. (P=0.034, P=0.007). The changes were less than 1.5 degrees. No significant difference was observed between the groups with or without bite plane regarding the changes of cephalometric variables during the treatment. The transverse dimension of the arch was increased significantly in both groups. The changes were similar in two groups. Conclusions: According to the results from this study, the presence of bite plane had no advantage over its absence. However, it seemed necessary to design a randomized clinical trial in this regard.

Acrylic resin teeth wear resistance has an important role in the denture longevity. This study aimed to clarify the effect of glaze coating on wear resistance of three types of artificial acrylic teeth.

In this in vitro study, the wear resistance rate of three of acrylic denture teeth (GENIUS, STON and CLASSIC) was compared with Ivoclar teeth (n=25/group). The wear resistance was measured by estimating the weight loss in pre and post removing glaze coating, following 5000 cycles in the chewing simulator device. Data analysis was made using paired t test, one-way ANOVA and Tukey’s post hoc test.

ANOVA test showed that there was no significant difference between the mean amount of wear of GENIUS, CLASSIC, STON and IVOCLAR teeth in the first stage (P <0.061), but this difference was significant (P <0.001) in the second stage. The result of Tukey post hoc test showed that wear rates of GENIUS were significantly lower than other groups (P<0.001). Comparison between the mean wear rates of each dental group at the first and second stages showed a significant difference between average teeth wear resistance of CLASSIC, STON and IVOCLAR in the first and second stages (P <0.001).

In conclusion, the teeth wear resistance of STON and CLASSIC were similar to IVOCLAR. Also, after removing the glaze coating, the teeth wear resistance decreased in all groups but was not statistically significant for group GENIUS.

Gingival biotype can be influenced by genetic factors, tooth-related factors and biological issues. This study aimed to determine the biotype of facial gingival and related factors.

In this study, 300 patients (128 males and 172 females) with a mean age of 36.2 ± 13.27 were selected by simple random sampling. Patients’ characteristics including age, gender, smoking, dental and keratinized gingival anatomy and oral hygiene parameters were recorded and their associations with gingival biotype were investigated using Transparency method. Collected data were analyzed by SPSS24 using t test, Mann-Whitney, ANOVA, and Pearson correlation coefficient. The P<0.05 was considered significant.

Frequency of thin gingival biotype was higher than that of thick gingival biotype. There was a significant relationship between gingival biotype of upper central incisors areas and age (P < 0.001), vibratory brushing (P=0.019) and keratinized gingival width (P=0.021). There was also a significant relationship between the gingival biotype of lower central incisor area and gender (P=0.036), vibratory brushing (P=0.010), vertical brushing (P=0.009) and keratinized gingival width (P=0.011). Moreover, a significant direct relationship was discovered between Gingival biotype of upper and lower central incisors areas. No relationship was found between frequency and duration of brushing, dental flossing, plaque index, tooth shape, and smoking with gingival biotype (P> 0.005).

Gingival biotype was associated with age, gender and keratinized gingival width, as well as some brushing characteristics such as the brushing method.

This finite element analysis (FEA) evaluated stress distribution in implant-supported overdenture (ISO) and peri-implant bone using one extracoronal (ball) and two intracoronal (locator and Zest Anchor Advanced Generation (ZAAG)) attachment systems.

In this in vitro study, the mandible was modelled in the form of an arc-shaped bone block with 33 mm height and 8 mm width. Two titanium implants were modelled at the site of canine teeth, and three attachments (ZAGG, locator, and ball) were placed over them. Next, 100 N load was applied at 90° and 30° angles from the molar site of each quadrant to the implants. The stress distribution pattern in the implants and the surrounding bone was analyzed, and the von Mises stress around the implants and in the crestal bone was calculated.

While minimum stress in peri-implant bone following load application at 30° angle was noted in the mesial point of the locator attachment, maximum stress was recorded at the distal point of the ball attachment following load application at 90° angle. Maximum stress around the implant following load application at 90° angle was noted in the lingual point of the ball attachment while minimum stress was recorded in the lingual point of the locator attachment following load application at 90° angle.

According to the results, the locator attachment is preferred to the ZAAG attachment, and the ball attachment should be avoided if possible.

Periodontitis is an inflammatory disease of the tooth-supporting structures that can lead to periodontal destruction and tooth loss. It is also a common complication of diabetes mellitus (DM) and tobacco smoking. In this regard, this study aimed to assess the effect of smoking on periodontal disease in diabetic patients.

This case-control study was conducted on 80 diabetic patients who were referred to the clinics of the Department of Periodontics of Ardabil University of Medical Sciences from October 2015 to April 2016. Participants were enrolled in this study in four groups (n=20). Groups 1 and 2 included smoker diabetic patients and 20 non-smoker diabetics, respectively. In addition, groups 3 and 4 served as the control groups and included healthy smoker and non-smoker individuals, respectively. The plaque index (PI), clinical probing depth (CPD), clinical attachment level (CAL), and bleeding on probing (BOP) were measured in the four groups.

The four groups were significantly different regarding the PI and CPD (P<0.05). The mean PI was higher in group 1 compared to groups 2 and 3. The highest mean CAL was recorded in group 1. Finally, non-diabetic smokers experienced the lowest mean BOP compared with other groups.

DM and tobacco smoking are the known major risk factors for periodontal disease, and the interaction effect of the two factors can aggravate the periodontal status in diabetic patients. Thus, dentists can take an important step in the healthcare system by encouraging their patients to control their DM and quit smoking.

The combination of chlorhexidine (CHX) and fluoride is believed to enhance the effects of both constituent elements, and reduce their possible side effects. This study aimed to evaluate the effect of CHX containing sodium fluoride on dental plaque, gingival inflammation, and tooth discoloration.

In this double-blind clinical study, 40 patients were selected and randomly divided into two groups. One group was given CHX 0.12%, and the other one was provided with sodium fluoride 0.05%-CHX 0.12% mouthwashes. Plaque index (PI), gingival index (GI), and discoloration index (DI) were measured at the beginning of the study and then after two weeks. Data were analyzed using chisquared and independent t test.

PI and GI were significantly reduced in the group with CHX + sodium fluoride compared to the one with CHX (P<0.001); however, the difference between two groups in terms of DI was not statistically significant (P =0.08). Both groups showed complications, but their differences were not statistically significant (P=0.5).

Mouth wash containing CHX + sodium fluoride was more effective in dental plaque control and gingival inflammation than the one only including CHX, although complications were not statistically significant between the two groups.

Information on tooth emergence is a key indicator for demonstrating maturity in the diagnosis of certain growth disturbances and an estimation of the chronological age of the children with unknown birth records in forensic dentistry. The association of dental and skeletal maturity with chronologic age among different populations has been investigated by several researchers. Early eruption of permanent molar appears to be a unique finding at such an early chronological age. The present report aimed to present a case of early eruption of mandibular second permanent molar in a seven-year-old girl.

Case Report: 

A seven-year-old girl was referred to the department of pediatric dentistry of Hamadan University with the chief complaint of an extra palatal tooth. Apart from the supernumerary tooth, mandibular second molars and premolars were fully erupted. Radiographic evaluation revealed a closure of the apex of the maxillary and mandibular incisors along with the first molars. For further investigations, the patient was referred to pediatric endocrinologist in order to rule out any systemic disease; however, patient’s test results did not show any systemic or hormonal problems. This case is one of the rare cases of early eruption of mandibular second molars at seven with no underlying problems. To our knowledge, no case of early eruption of second permanent molar has been reported in a seven-year-old child and early eruption of second molar appears to be a unique finding at such an early chronological age.

Any change in sequence or timing of the normal tooth eruption is not common, and it needs prepared eyes and adequate knowledge to diagnose and examine it in a timely manner.