Prevalence and Features of Maxillary Sinus Septa in Patients with Cleft Lip and Palate: Cone Beam Computed Tomography Imaging Technique

OBJECTIVE

The development of the maxillary sinus is different in patients with cleft lip and palate (CLP) compared to non-CLP individuals. To investigate the prevalence and features of maxillary sinus septa (MSS) in patients with CLP in comparison with the non-CLP population.

DESIGN

Retrospective study.

INTERVENTION

Cone beam computed tomography (CBCT) evaluation.

SETTING

CLP center in Shiraz faculty of dentistry, Iran.

PATIENTS

A total 306 sinuses (88 cleft and 218 noncleft) on 153 images (CLP group: n  =  66; control group: n  =  87) were examined to determine the prevalence of septa and characterize them.

MAIN OUTCOME MEASURES

Sinus septa were characterized according to height, orientation, angle, origin, and location. The chi-square test, Mann-Whitney U test, and Fisher's exact test were used for statistical analysis.

RESULTS

The prevalence of septa was 28.9% and 32.1% in the CLP and control groups, respectively. No significant difference was found between the study groups in terms of prevalence, location, and orientation of MSS. The average height and angle of septa were significantly higher in the control group compared to the CLP group. Inferior origin was significantly more prevalent in the control group than in the CLP group (P = .004).

CONCLUSION

There was no difference in the prevalence of MSS between patients with CLP and non-CLP individuals. However, certain features of the septa were different in patients with CLP.

The Esthetic Perception of Morphological Severity in Scaphocephalic Patients is Correlated With Specific Head Geometrical Features

OBJECTIVE

To investigate the relationship between perception of craniofacial deformity, geometric head features, and 3D head shape analyzed by statistical shape modeling (SSM).

PATIENTS

A total of 18 unoperated patients with scaphocephaly (age  =  5.2  ±  1.1m)-6 were followed-up after spring-assisted cranioplasty (SAC) (age  =  9.6  ±  1.5m)-and 6 controls (age  =  6.7  ±  2.5m).

MAIN OUTCOME MEASURES

3D head shapes were retrieved from 3D scans or computed tomography (CTs). Various geometrical features were measured: anterior and posterior prominence, take-off angle, average anterior and posterior lateral and horizontal curvatures, cranial index (CI) (cranial width over length), and turricephaly index (TI) (cranial height over length). SSM and principal component analysis (PCA) described shape variability. All models were 3D printed; the perception of deformity was blindly scored by 9 surgeons and 1 radiologist in terms of frontal bossing (FB), occipital bulleting (OB), biparietal narrowing (BN), low posterior vertex (LPV), and overall head shape (OHS).

RESULTS

A moderate correlation was found between FB and anterior prominence (r  =  0.56, P < .01) and take-off angle (r  =  - 0.57, P < .01). OB correlated with average posterior lateral curvature (r  =  0.43, P < 0.01) similarly to BPN (r  =  0.55, P < .01) and LPV (r  =  0.43, P < .01). OHS showed strong correlation with CI (r  =   - 0.68, P < .01) and TI (r  =  0.63, P< .01). SSM Mode 1 correlated with OHS (r  =  0.66, p < .01) while Mode 3 correlated with FB (r  =   - 0.58, P < .01).

CONCLUSIONS

Esthetic cranial appearance in craniofacial patients is correlated to specific geometric parameters and could be estimated using automated methods such as SSM.

Evaluation of torsional strength and torque presentation of coated rectangular stainless steel archwires, an in vitro study

OBJECTIVES

An in vitro experimental study was performed to evaluate the torsional strength and torque released by esthetic coated archwires.

MATERIALS AND METHODS

A total of 52 coated (study group) and 52 stainless steel (control group) rectangular archwires from two manufacturers (brand I: Gestenco International AB, Gothenburg, Sweden and brand II: Ortho Technology, Lutz, FL, USA) in two sizes (0.019 × 0.025 and 0.017 × 0.0250-inch) were evaluated. The straight parts on both ends of each preformed archwire were cut in 30 mm segments. A specially designed experimental device was attached to the universal testing machine (Model Z020, Zwick Roell, Ulm, Germany) to measure torsional strength and to calculate the clinically significant torque interval. The groups were compared based on their brand, presence of coating and size using three-way analysis of variance (ANOVA) test at a significance level of 5%.

RESULTS

The results revealed that coating of the wires of brand 1 resulted in a significant reduction of torsional strength in both wire sizes (P-value = 0.0001). For the wires of brand 2, coating of the 0.017 × 0.025-in wire resulted in a significant reduction in torsional strength. However, for the 0.019 × 0.025 in wire size, the presence of coating significantly increased the torsional strength (P-value = 0.0001). Coating did not affect the measured clinical torque interval of the analyzed wires when a torque between 5 and 20 Nmm was applied (P-value = 0.062).

CONCLUSIONS

Mechanical behavior of coated archwires depends mainly on the thickness of their inner core alloy. Reduction in the diameter of the inner alloy resulted in reduced torsional strength. Despite lower mean torsional strength, in the settings of this study, coated and conventional wires demonstrated comparable torque angles if loaded in the typical range of activation.

Three-Dimensional Assessment of Eustachian Tube in Patients With Cleft Palate Versus Controls: A CBCT Study

To compare the morphological characteristics of the Eustachian tube (ET) between patients with cleft palate and healthy controls with the use of cone-beam computed tomography (CBCT).

Retrospective assessment of treated nonsyndromic patients with cleft palate and a control group.

CBCT images of 51 patients with cleft palate who had previously undergone surgery to close the cleft palate and a control group of 51 patients were included in this study. Syndromic patients were excluded.

The cleft group were divided into 3 groups according to the palatoplasty technique, which was done in the infancy period to close the cleft palate (Nadjmi modification of Furlow, Sommerlad, and V-Y pushback). Finally, ET length (ETL), ET angle, and auditory tube angle (ATA) were measured in all patients.

The ETL, ETA, and ATA in the cleft and the normal control groups were 29.73 ± 3.14 and 32.18 ± 3.34 mm, 33.18 ± 2.57 and 35.40 ± 3.93, and 141.64 ± 4.13 and 138.87 ± 4.96, respectively. All 3 features were statistically significant among the groups (All Ps < .05). ETL and ETA were significantly higher in Nadjmi modification of Furlow and Sommerlad palatoplasty techniques compared to the V-Y pushback technique, while there was no significant difference in the ATA between the palatoplasty groups.

Cleft palate can significantly affect the morphological characteristics of the ET. Type of the infancy palatoplasty can influence some of its dimensions.

Epidemiological and Spatiotemporal Descriptive Analysis of Patients with Nonsyndromic Cleft Lip and/or Palate: A 12-Year Retrospective Study in Southern Iran

Objectives

The current study is aimed at evaluating epidemiological characteristics and spatiotemporal distribution of cleft lip and/or palate (CL/P) in the south of Iran.

Methods

Data were extracted from the 1840 medical records of patients who were referred to the Cleft Lip and Palate Center of Shiraz University of Medical Sciences, from January 1, 2011, to September 1, 2022. The collected variables included demographic data (gender, birth date and season, place, birth order, and weight), cleft types and the subtypes, parental information (health status, education level, marital status, and age during the pregnancy), and other basic parameters. The chi-square test at a significance level of 0.05 was used to analyze collected data. The geographic information system (GIS) analysis was also used for analyzing the spatial distribution of CL/P patients.

Results

Based on our inclusion criteria, 1281 nonsyndromic patients were included in this study. The most common type was cleft lip and palate (CLP) with 48.32%, whereas cleft palate (CP) and cleft lip (CL) accounted for 40.75% and 10.93% of the patients, respectively. There was a progressive increase in the frequency of all types of clefts, and most of them were male (P ≤ 0.001). The urban population outnumbered the rural ones in all provinces. Parents were mostly healthy (>80%) with low educational status (47.5%). Most born CL/P patients were from consanguineous marriages (58.9%), especially between first-degree relatives. A majority of CL/P patients (73.1%) were born in the first two gestations with a birth weight of 2500-4000 g (77.4%). Most infants with CL/P (84.3%) were born from mothers who had at least one of the predisposing factors.

Conclusion

In this study, the frequency of cleft types and subtypes was similar to the existing literature. However, high rate of consanguineous marriage, especially between first-degree relatives, was the most notable feature of this population.

Characteristic changes of the palatal rugae following orthodontic treatment

Background

Because of the individuality of the palatal rugae, they are applicable for human identification purposes the same as the fingerprints. Therefore, it is important to assess the effect of different factors on rugae characteristics. We assessed the characteristic changes of the palatal rugae following extraction and expansion during orthodontic treatments. Before and after orthodontic treatment dental casts of 30 patients were scanned by 3Shape Trios 3D intraoral scanner, and superimposed in Geomagic X 2018 software. Displacement of 13 reference points was analyzed in three dimensions. The length of the palatal rugae was also measured. SPSS version 22.0 was applied for data analysis, using independent t test, sample t test, and chi-square test.

Results

The alterations in the mean palatal rugae length were significant in the first right and third right ridges after extraction, and right and left second ridges after expansion treatment (P < 0.05). Changes in coordinates in the X, Y, and Z axes were significant at 8 points on the rugae after extraction, and 5 points after expansion treatment (P < 0.05). The changes in the sum of means of displacements were significant at all 13 points after extraction and expansion treatments (P < 0.05).

Conclusions

The palatal rugae do not remain stable during expansion and extraction orthodontic treatments. Some changes occurred in length, and the most medial and most lateral points on each ridge were displaced. The length of the incisive papilla did not change during treatment; thus, it can serve as a stable landmark. If we consider palatal rugae as an individual landmark, we can refer the patients after orthodontic treatment for scanning of their palatal rugae to document their post treatment pattern; but it should be noted that treatment relapse may change it again.

Comparison of the mechanical properties and surface topography of as-received and as-retrieved Copper-Nickel-Titanium arch wires: An ex-vivo study

AIM

The mechanical and surface characteristics of Copper NiTi wires following intraoral aging in an important topic. This ex-vivo study is designed to assess the three most important mechanical properties; torsional stiffness, 3-point bending and surface hardness of the as-received Copper NiTi orthodontic archwires and compare them to the retrieved ones.

MATERIAL AND METHODS

In this study, 50 round CuNiTi (0.016 inch) and 50 rectangular (0.018×0.025 inch) CuNiTi orthodontic wires (American Orthodontics, Tanzo Copper Nickel Titanium, Sheboygan, WI) were tested. The groups were as follow: 25 as-received 0.016 inch round CuNiTi archwires (group 1), 25 as-retrieved 0.016 inch round CuNiTi archwires (group 2), 25 as-received 0.018×0.025 inch rectangular CuNiTi archwires (group 3), and 25 as-retrieved 0.018×0.025 inch rectangular CuNiTi archwires (group 4). The physical properties of all of the samples were examined using Vickers hardness, bending and torsional tests. The Kolmogorov-Smirnov test was applied to assess the normal distribution of data. An independent t-test was used to compare the variables between the groups.

RESULTS

The results showed that the hardness does not significantly differ between the as-received and as-retrieved archwires in both 0.016 and 0.018×0.025 inch archwires (P< 0.05). The bending test of the round wires showed that the values of the activation forces in the as-received ones were significantly higher than those of the as-retrieved (P=0.00). The torsional and bending test results of rectangular wires showed that the amounts of forces exerted from the as-retrieved archwires were significantly higher than the new archwires (P=0.00).

CONCLUSIONS

Round CuNiTi archwires could be retied in the succeeding visits. However, the bending activation that declines significantly should be took into consideration. On the other hand, since bending and torsion activation of CuNiTi rectangular archwires increased after intraoral use, these wires should be retied cautiously.

The effect of multiple enamel conditioning on enamel micro-hardness

BACKGROUND

White spot formation is one of the common side effects in orthodontic treatments and multiple enamel conditioning might happen even during on session of fixed orthodontic treatments. The aim of the present study was to evaluate the impact of multiple enamel conditioning with different methods on enamel micro-hardness (MH).

MATERIALS AND METHODS

In this In vitro experimental study, the buccal surfaces of 105 extracted premolars were evaluated in seven groups: One control and six experimental groups. The enamel conditioning was performed in three ways: Etching with phosphoric acid 37%, etching with phosphoric acid 37% followed by primer application and conditioning with self-etch primer. The conditioning process in each way was also performed twice consecutively. The specimens were submitted in pH cycling model with demineralization and re-mineralization solutions for 14 days. Afterward Vickers MH test was applied with 0.981N force on the teeth for 10 s indentation time. Data were analyzed using One-Way ANOVA and Tukey HSD (honestly significant difference) test for multiple comparisons. A value of P < 0.05 was considered statistically significant.

RESULTS

MH analysis showed statistically significant differences between the control group and the other conditioned groups (P < 0.05). The groups conditioned with acid-etch and primer, particularly twice, showed the lowest amount of MH in comparison to other groups. Self-etch primer had the least effect on MH of the enamel. Single time etching without using primer, made no considerable difference when compared to multiple etching.

CONCLUSION

Etching process and covering the enamel with primer decrease enamel MH. Using self-etch primer is a more conservative method of enamel conditioning.

The adjunctive effect of autologous platelet concentrates on orthodontic tooth movement: A systematic review and meta-analysis of current randomized controlled trials

OBJECTIVE

To evaluate the effectiveness of autologous platelet concentrates (APCs) as adjuncts on accelerating orthodontic tooth movement (OTM) of the human subjects undergoing orthodontic treatment and to critically appraise the available literature.

METHODS AND MATERIALS

Five electronic databases (PubMed, Scopus, Web of Science, Embase, and Cochrane Central Register of Controlled Trials) were searched from 2000 up to May 2021 to retrieve eligible randomized controlled trials (RCTs) investigating patients who underwent orthodontic treatment that involved OTM of maxillary and mandibular incisors and canines. All the enrolled cases were treated with APCs and had no local or systemic interfering factors. The quality of the included studies was assessed using the modified JADAD scale. The effect sizes were assessed using mean difference (MD). The heterogeneity analysis was conducted using (I²) statistic at α=0.10.

RESULTS

Finally, seven RCTs were included in the qualitative, and two RCTs were included in the quantitative analysis. The meta-analysis was performed regarding the effect of injectable platelet-rich fibrin (I-PRF) on the rate of canine tooth movement in millimeters at different intervals of the 1^st, 2^nd, and 3^rd months. In the 1^st month, I-PRF (WMD:0.12mm, CI95% -5.01 to 5.24, I²=90%) did not significantly affect OTM. In the 2^nd month, I-PRF (WMD:0.66mm, CI95% 0.60 to 0.73, I²=10%) significantly increased the OTM. However, in the 3^rd month, I-PRF did not significantly increase the OTM (WMD:0.54mm, CI95% -1.38 to 2.47, I²=67%).

CONCLUSIONS

According to the low certainty of evidence about this topic, providing a definite conclusion is not possible. However, applying I-PRF seems to be efficient in accelerating the OTM of the canines. Further high-quality studies with larger sample sizes will be indispensable to validate this conclusion.

Use of nano-hydroxyapatite serum and different finishing/polishing techniques to reduce enamel staining of debonding after orthodontic treatment : A randomized clinical trial

PURPOSE

The aim of this study was to assess the effect of nano-hydroxyapatite serum and different finishing, polishing techniques on color alterations of enamel caused by debonding procedures after comprehensive orthodontic treatment by use of a spectrophotometer.

METHODS

This randomized clinical trial recruited 20 participants with previous non-extraction orthodontic treatment and acceptable hygiene to evaluate enamel staining after orthodontic debonding. The usage of a carbide bur alone, as the conventional method, and the combination use of carbide burs and Sof-Lex discs (3M™ ESPE, St. Paul, MN, USA) were compared to each other followed by 10 days application of nano-hydroxyapatite after debonding. Then the enamel staining was evaluated by a reflectance spectrophotometer in three periods: immediately, and 2 and 4 months after debonding.

RESULTS

The comparison of the groups showed a significant interaction between Sof-Lex groups and the control side after the first interval of the study (p = 0.042). Application of nano-hydroxyapatite demonstrated no significant difference in color parameters between upper and lower arches of the participants at all intervals of this study (p > 0.05). The mean total color change (ΔE) in all groups and between all intervals had been clinically perceptible (ΔE > 3.3).

CONCLUSIONS

The applied concentrations of nano-hydroxyapatite had no significant effect in reducing tooth color changes after debonding in orthodontic treatment. Sof-Lex discs can significantly reduce tooth color changes in a short time.

Farsi version of the CLEFT-Q: translation, cultural adaptation process and reliability

Background

The purpose of this study was the translation and cultural adaptation of the CLEFT-Q to Farsi and evaluating the reliability of it.

Methods

The English version of the CLEFT-Q was translated to Farsi following the guidelines set forth by the International Society for Pharmacoeconomics and Outcomes Research (ISPOR). To calculate the reliability, 50 participants filled out the Farsi version of the questionnaire twice at 2-week intervals.

Results

The difficulties during the translation and cultural adaptation process were as follows: 7.56% of items from the independent forward translations, 62.18% of items from the comparison between two forward translations, and 21% of items from the comparison between post-back translation and the original version. The internal consistency and stability of the Farsi version of the CLEFT-Q were 0.979 and 0.997, which both were categorized as excellent.

Conclusion

The Farsi version of the CLEFT-Q is a valid and reliable tool currently available for Farsi-speaking families around the world.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01957-7.

In Vitro evaluation of immediate cytotoxicity of resterilised orthodontic bands on HGF-1 cell line

OBJECTIVES

The aim of this study was to evaluate the immediate cytotoxic effects of orthodontic molar bands, on HGF-1 cell line, after multiple times of sterilization following size selection procedure.

MATERIAL AND METHODS

48 stainless steel orthodontic molar bands were divided into 4 groups according to times of sterilization (1, 2, 4 and 8 times). A liquid extract containing the ions released from each band was prepared and the HGF-1 cell line was exposed to the extracts. 2 control groups (positive and negative) were designated. An MTT assay was performed, and the absorbance was read at 492nm in a microplate reader (Antos 2020, Austria).

RESULTS

There was no significant difference in pure optical density (OD) among the 4 groups (P=0.749) however a statistically significant difference was seen between the positive control group and other 4 groups (P<0.001).

CONCLUSION

The stainless-steel orthodontic bands used in this study were inert as manufactured and even multiple times of sterilization did not decrease the biocompatibility of these bands for clinical use. The present study shows that clinicians can sterilize the tried-in molar bands for at least 8 times without any risk of cytotoxicity for patients.

Evaluation of flexural strength and antibacterial effect of orthodontic acrylic resins containing Galla chinensis extract

Objective:

To evaluate different concentrations of Galla chinensis extract (GCE) added to poly(methyl methacrylate) (PMMA), which is widely used for fabrication of removable orthodontic appliances, regarding the effectiveness of this herbal extract on antimicrobial effect and flexural strength of PMMA.

Methods:

Acrylic resin samples containing 0.4%, 0.8% and 1.6% GCE were prepared. Flexural strength was investigated via three-point flexural strength test for the 15 acrylic resin blocks of each concentration. Disk diffusion test was used to evaluate antibacterial effects of incorporating the same concentrations of GCE into acrylic resin. All these three groups were compared with the control group, with no added GCE, regarding flexural strength and antibacterial properties.

Results:

Comparison of flexural strength between the three study groups and the control group showed significant differences between the groups (P=0.018). However, there was no significant difference between the groups containing GCE. There were significant differences in antimicrobial activity between the four groups (P=0.026).

Conclusion:

Within the limitations of this study, it is suggested that incorporation of GCE into PMMA would be beneficial for antimicrobial activity and flexural strength of PMMA, but further studies on other physical properties and antimicrobial effects on other bacterial strain would be beneficial prior to clinical investigations.

Effect of high concentration nano-hydroxyapatite serum on shear bond strength of metal brackets following three different enamel surface preparation methods: An in vitro study

OBJECTIVE

White spot lesion (WSL) is one of the most important complications of fixed orthodontic treatment. Many methods have been studied to prevent this problem. This study is aimed to investigate the effect of high concentration nano-hydroxyapatite (nHAP) on shear bond strength (SBS) of metal brackets and Adhesive Remnant Index (ARI) score in different preparation methods.

MATERIAL AND METHODS

Sixty human premolars, which were extracted for orthodontic reasons were included in this in vitro study. The teeth were randomly divided into 4 groups of 15 each: one control group and three nHAP groups. After applying nHAP for 2 to 3 minutes daily for 10 days, the groups 2 to 4 underwent sandblasting using 50μm aluminium oxide and 30 seconds etching, 60 and 30 seconds etching, respectively, and the brackets were then bonded to the teeth. After debonding, SBS and ARI scores were recorded. Data were analysed using the ANOVA test and posthoc test for pairwise comparisons.

RESULTS

No significant difference was observed in SBS between the control group and the nHAP groups. The sandblasted teeth showed significantly higher SBS than the 30 seconds etching after nHAP application (P=0.02). The teeth etched for 60 seconds showed a significantly higher ARI score than the 30 seconds etched teeth with (P=0.003) or without (P<0.001) nHAP application.

CONCLUSIONS

The use of nHAP before bracket bonding can be considered as a caries preventive method since it did not compromise the SBS. Sixty seconds etching is recommended for less likely damage to the enamel after debonding.

Prevalence of Malocclusion and Occlusal Traits in Children with Autism Spectrum Disorders

Background

The purpose of this cross-sectional study was to evaluate the prevalence of malocclusion in children with autism spectrum disorders (ASDs) and to determine the most common occlusal traits.

Materials and Methods

The present cross-sectional study was conducted among 7–15 years old children with ASDs and randomly selected healthy children with the same demographic characteristics. Molar relationship, lip incompetence, overbite, overjet, midline deviation, crossbite, and crowding/spacing were recorded. A descriptive analysis was performed for all variables. A comparison of the presence or absence of malocclusion traits between children with and without ASDs was assessed using the chi-square test. Univariate and multivariate logistic regressions were used to calculate odds ratio (OR) and 95% confidence intervals (95% CI) to assay various parameters between autism and non-autism group.

Results

A total of 96 patients were assessed, 47 patients in the ASD group, and 49 in the control (non-ASD) group. The results showed no significant difference between the ASD and control groups in terms of the overall prevalence of malocclusion (P>0.05). However, the prevalence of increased overjet and Class II molar relationship was significantly higher in the ASD group compared to the control group (P=0.03). Patients in the control group showed a higher prevalence of midline deviation (P=0.001).

Conclusion

Despite a higher prevalence of overjet and Class II molar relationship in children with ASDs, the prevalence of malocclusion was not higher in this group of patients.

Effect of mini-screw-facilitated micro-osteoperforation on the rate of orthodontic tooth movement: a single-center, split-mouth, randomized, controlled trial

Objective

The present study aimed to evaluate the effect of MOP over a 3-month period and to determine the influence of the number of perforations on the rate of canine retraction. In addition, the amount of pain and discomfort caused by the MOP method was evaluated.

Trial design

A single-center, split-mouth, triple-blind, randomized, controlled trial was conducted.

Methods

The clinical trial was conducted from December 2018 to July 2019 in the Orthodontic Clinic, Shiraz Dental School. Twenty-eight patients (range from16.3 to 35.2 years) who need fixed orthodontic treatment were recruited and randomly assigned to MOP1 and MOP2 groups. In each patient one side of the mouth worked as a control side which received no MOPs. Four months after first premolars extraction, patients in MOP1 group received 3 MOPs on the buccal surface of alveolar bone in the experimental side to accelerate canine retraction whereas patients in MOP2 group received 3 buccal MOPs and 3 palatal MOPs in the experimental side. The amount of canine retraction was measured every 28 days at three intervals on both sides of the mouth. Pain perception was also measured on the day of MOP procedure and subsequently at 24 h. Randomization was performed using online software RANDOM.ORG; the recruited patients were divided into two parallel groups with a 1:1 allocation ratio then the side of MOPs intervention in each subject was randomly determined with coin tossing. Triple blinding design was employed.

Results

The result of the intra-examiner reliability using ICC was 0.97 (P <  0.001), indicating excellent repeatability and reliability of the measurements. The baseline characteristics between the groups were similar (P > 0.05). There was a significant difference in the rate of canine retraction between the MOP groups and the contralateral control sides, as well as between the MOP1 and MOP2 groups (P <  0.05).

Conclusion

The MOP procedure was effective in accelerating orthodontic tooth movement, although the amount of acceleration was not clinically significant in the case of canine retraction. An increase in the number of MOPs resulted in a significant acceleration of the canine retraction.

Trial registration

The trial was registered 30 November 2018 at the Iranian Registry of Clinical Trials (IRCT20181121041713N1).

Dentoskeletal effects of class II malocclusion treatment with the modified Twin Block appliance

Background

The purpose of this study was to prospectively assess the dentoskeletal effect of a modified Twin Block appliance for treatment of class II malocclusions.

Material and Methods

Lateral cephalograms of 25 Class II malocclusion patients were compared to evaluate skeletal, dentoalveolar and soft tissue changes pre- and post-treatment with a modified Twin Block appliance. A total of 33 angular and linear variables were used for analysis. The differences were calculated at the start and end of treatment. The paired T test was performed to compare the cephalometric measurements before and after treatment.

Results

Compared the pre- and post- treatment measurements, there was a significant increase in SNB (P<0.001), CO-Gn (P<0.001), ANS-Me (P=0.001), Mandibular base (P<0.001), Lower 1 to NB (°) (P=0.004), Lower 1 to NB (mm) (P<0.001), and Z-angle (P=0.001) following functional therapy with modified Twin Block appliance. On the other hand, a significant decrease was observed in ANB (P<0.001), NA-Pog (P<0.001), overjet (P<0.001), and overbite (P=0.007), Upper 1 to palatal plane (P=0.007), UL-E-line (P<0.001), LL-E-line (P=0.001), and H-angle (P=0.002) after treatment with modified Twin Block appliance.

Conclusions

The modified Twin-Block improves facial esthetics in Class II malocclusion by a combination of changes in skeletal as well as dentoalveolar structures. The increase of mandibular unit length was observed to be due to a true mandibular growth not just a repositioning of the mandible. The modified appliance, however, did not show any superior effects in terms of less dental compensation compared to the conventional Twin–Block appliance.

Key words:Dentoskeletal effect, Modified Twin Block, Class II malocclusion.

Difficulty of palatal impacted canine treatment in different sagittal and vertical skeletal malocclusions: A retrospective 3D evaluation

OBJECTIVE

To evaluate the difficulty of impacted canine treatment in different kinds of sagittal and vertical malocclusion using the KPG index, a novel 3D classification system for canine impaction.

MATERIALS AND METHODS

In this cross-sectional study, 74 cone-beam computed tomography (CBCT) images of subjects with palatally impacted canines were collected from one dental radiographic clinic. Impacted canines were assessed and KPG index of difficulty of treatment was calculated for each tooth. Lateral cephalograms corresponding with each CBCT were also traced and analysed. To assess the relationship between the level of treatment difficulty and type of malocclusion, the Chi² test was used. The Kruskal-Wallis H test was used to assess the difficulty score between the three classes of malocclusion.

RESULTS

There was no correlation between different sagittal skeletal measurements and treatment difficulty of impacted teeth (P>0.05). A positive correlation was shown between KPG index and linear measurements of A to Pn and facial angle (FH-N Pog) (P<0.05). Difficulty of treatment did not differ among various patterns of vertical growth.

CONCLUSION

Treatment of impacted canines is more difficult in patients with maxillary prognathism and it is recommended that these patients be more meticulously evaluated prior to treatment.

Evaluation of Smile Characteristics in Three Different Sagittal Malocclusions Before and After Nonextraction Orthodontic Treatment

Introduction:

To investigate the smile esthetics variables in three malocclusion classifications of angle to find out if the final smile esthetics was correlated with the initial types of malocclusion.

Materials and Methods:

This cross-sectional study was performed on 90 adult patients (18–28 years old) with three classes of malocclusion (n = 30 for each class), who were just treated by an orthodontist based on standard edgewise (0.018 inch). A standardized smile mesh analysis was used to evaluate seven smile characteristics.

Results:

Orthodontic treatment improved all the smile characteristics in the three groups. All groups showed an increase in smile width, smile index, and vertical indices; while, the transverse indices decreased. Significant increase was observed in four smile measurements in patients with Class II malocclusion. Comparing the smile characteristic changes among the three groups revealed that the changes induced by orthodontic treatment were significantly higher in patients with Class II malocclusion.

Conclusion:

The smile esthetics in all the three types of malocclusion benefited from the orthodontic treatment; however, the changes were more significant in Class II malocclusions. None of the three malocclusion types showed significant difference between the pre- and post-treatment smile characteristics.

Photogrammetric Evaluation of Soft Tissue Profile and Frontal Photographs in Repaired Bilateral Cleft Lip and Palate

OBJECTIVE

To evaluate the soft tissue profile and frontal photographs of 8- to 12-year-old patients with repaired complete bilateral cleft lip and palate (BCLP).

METHODS

The profile and frontal photographs obtained from 31 nonsyndromic BCLP children (aged 8-12 years: 14 boys and 17 girls) were analyzed and compared with an age- and sex-matched normal population (18 boys and 32 girls). In each patient, 12 soft tissue angular and proportional parameters on the frontal photograph and 12 angular parameters for the profile photographs were developed and measured. Student t test was used to compare the mean value of the parameters between both sexes.

RESULTS

In the frontal view, there was a significant difference between the 2 study groups in the facial symmetry angle (P < .001), lower facial height proportion (P < .001), upper lip proportion (P < .001), and interalar width/distance between the inner canthus of the eyes (P < .001). In the profile view, there was a significant difference between the control group and the patients with cleft lip and palate in terms of nasofrontal angle (P < .001), nasal angle (P < .001), angle of the inferior facial third (P = .032), head position angle (P < .001), facial convexity angle (P < .001), total facial convexity angle (P < .001), and vertical nasal angle (P < .001).

CONCLUSION

In comparison with the normal population, the face of patients with repaired BCLP showed several soft tissue deformities, especially in the nasofrontal region, even after a surgical repair.

Characteristics of Palatal Rugae Patterns as a Potential Tool for Sex Discrimination in a Sample of Iranian Children

STATEMENT OF THE PROBLEM

Palatal rugae have been considered equivalent to fingerprints, as they are unique to each individual. It has been shown that palatal rugae are associated with specific racial groups and are known to aid sex identification. Due to the lack of any published data on palatal rugae morphology on Iranian children, the present study was performed.

PURPOSE

The present study aimed to investigate differences in the morphology of individual palatal in a sample of Iranian children. Additionally, it is intended to develop discriminant function to identify sex, based on rugae morphology.

MATERIALS AND METHOD

A total of 120 pre-orthodontic casts were evaluated for different rugae patterns using the Thomas and Kotze classification. The casts were equally distributed between sexes with an age range of 6-12 years. Rugae length, shape, and associated morphology were recorded and the independent t-test and Chi-square test were used to compare the mean and relationship between the attributes. The discriminant function analysis was applied to the data in order to determine the applicability of palatal rugae patterns as an aid for sex identification.

RESULTS

While the total rugae count showed an insignificant difference between the males and females, the rugae count on the right side of the palates showed a significant difference (p= 0.046). The primary rugae were most common in both sexes, followed by the secondary and fragmentary rugae. The most prevalent rugae shape between both sexes was the wavy rugae followed by the curve and straight shapes in males and the straight and curve shapes in females. A significant difference was observed in the number of the curve rugae between the sexes. Discriminant function analysis allowed sex differentiation with an accuracy of 60.8%.

CONCLUSION

Palatal rugae shapes are unique to each individual and could be used as a potential tool for sex identification. Further research on a larger sample is required to fully confirm the application of this method (e.g. in forensic medicine) as a complementary technique for sex identification.

A qualitative study of children's quality of life in the context of living with cleft lip and palate

Background and objective

Quality-of-life measures have been expanded to help in assessing the physical and psychosocial effects of oral health. Although, in the case of children undergoing oral surgery, the oro-facial status is generally measured by studies, it is essential to carry out investigations into the level of quality of life (QoL) after surgery to assess the actual effect of these surgeries on children’s lives. Hence, our study is aimed at evaluating the QoL in these children.

Methods

The study was performed using qualitative content analysis method. Eighteen caregivers of 4–6 year old children with a history of unilateral cleft lip and palate participated in in-depth interviews about the children’s experiences with different problems affecting their daily lives. The results were divided into codes, sub-categories and categories through an inductive process in which the researchers moved from the specific to the general.

Result

A number of problems were identified, particularly insufficient functional and socio-emotional well-being including, difficulty in eating and speaking, dento-facial problems, shame, anxiety, insufficient peer interaction and dissatisfaction with their own appearance.

Conclusion

The most critical problems derived from the participants’ experiences were insufficient functional and socio-emotional well-being that contributed to the reduced QoL among these children. Long term multidisciplinary interventional strategies such as psycho-social supportive programs are required to improve the QoL of these children. These interventions should be considered from the early stages of treatment, or even early stages of diagnosis.

Peptide-biofunctionalization of biomaterials for osteochondral tissue regeneration in early stage osteoarthritis: challenges and opportunities

Osteoarthritis is a degenerative joint disease characterized by the progressive deterioration of articular cartilage, synovial inflammation and changes in periarticular and subchondral bone, being a leading cause of disability.

The Application of Palatal Rugae for Sex Discrimination in Forensic Medicine in a Selected Iranian Population

BACKGROUND

Palatal rugae have been shown to be associated with racial and geographical variations and are known to be useful in sex identification. The present study aimed to assess palatal rugae patterns in a sample Iranian population and to compare the results with those from other studied populations.

METHODS

During summer 2017, 130 pre-orthodontic plaster casts from patients aged 17-25 years (65 males and 65 females) were obtained from the Department of Orthodontics, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran. The castes were evaluated using the classification given by Thomas and Kotze followed by recording the rugae lengths and shapes. The data were analyzed with the SPSS statistical software package (version 15.0) using the unpaired t test and Chi-square test. P<0.05 were considered statistically significant. Additionally, discriminant function analysis was applied to determine the applicability of palatal rugae patterns as a tool to aid sex identification.

RESULTS

The rugae count showed an insignificant difference between the Iranian males and females. The primary rugae were most common in both sexes followed by the secondary and fragmentary. Significant differences were observed between the sexes and the number of primary rugae in males (P=0.03) and fragmentary rugae in females (P=0.04) on the left side of the palate. A significant difference in the straight and diverging unification types was observed, which was highest in males (P=0.01) and females (P=0.03), respectively. Discriminant function analysis enabled sex identification with an accuracy of 70%.

CONCLUSION

Palatal rugae is shown to be an appropriate tool for sex identification in an Iranian population. Further studies with a larger sample size are required for a comprehensive outcome.

Impact of oral clefts on the oral health-related quality of life of preschool children and their parents

Objective

To assess the oral health-related quality of life (OHRQoL) of preschool children with cleft lip and palate (CLP) and their relatives.

Materials and Methods

In this cross-sectional study, 55 2-5-year-old children with the history of CLP were randomly selected from those referred to Shiraz Lip and Palate Cleft Research Center and treated with single-stage closure (Push back palatoplasty). Furthermore, same number of children with the same age who attended the Shiraz School of Dentistry for routine dental care were selected as control group using randomized sampling. Children's demographic data were obtained from their parents. Farsi version of the Early Childhood Oral Health Impact Scale (F-ECOHIS) was used for evaluating these children's QoL.

Results

We found a significant difference in OHRQoL between children with CLP and children without CLP in the overall score of F-ECOHIS and all of subscales. In the impact on children subscale, the difference between these groups was remarkable in limitations' domain. As for difficulties faced by children, question on "difficulty in pronouncing words" had the highest average score. Furthermore, in impact on family, in parental distress domain, the difference between these groups was remarkable. For difficulties faced by family, financial impact got the highest average score. No significant difference was found between boys and girls with CLP in all subscales. While according to the score of total F-ECOHIS in unilateral and bilateral CLP children, there was statistically significant difference in these groups.

Conclusion

Since oral clefts affect the QoL of children and their families even after the usual treatments, the implementation and maintenance of multidisciplinary interventional strategies are required for establishment of facial esthetics, oral function, and psychological support for such individuals.

Bolton discrepancy in an Iranian population and its relation with maxillary lateral incisors' size

Background

Bolton's two main ratios describing the proportional size of upper and lower teeth, could contribute to estimating the excess or deficiency of tooth size necessary to obtain an ideal occlusion. However, the mean Bolton values are not the same among different societies. Determining the prevalence of tooth size deviations from population-specific Bolton indices might help local orthodontists to have a more concise treatment plan.

Objective

The study aimed to define the prevalence of clinically significant tooth size discrepancies (TSD) in an Iranian population and to evaluate the influence of lateral incisors' size on this discrepancy.

Methods

This cross-sectional study was conducted on study casts of orthodontic patients attending Imam Reza Dental Clinic from September 2008 to December 2016. The sample comprised of 150 randomly selected pre-treatment study casts (64 males and 86 females from 17 to 28). The mesiodistal diameter of all permanent teeth from the first molar on the right to the first molar on the left was measured using 2 similar digital calipers, and Bolton analysis was calculated. Subjective visual estimation of Bolton discrepancy was also performed. SPSS v18.0, Wilcoxon signed ranks test, Pearson correlation and Receiver Operating Characteristic (ROC) curve analysis were used for statistical analysis. A p<0.05 was considered statistically significant.

Results

In the sample group, 34.7% had anterior Bolton index (ABI) and 20.7% had total Bolton index (TBI) greater than 2 Standard Deviations (2SDs) of Bolton's means, and about half of them required correction of the ABI considering the actual size of discrepancies (mm). The sensitivity of estimating clinically significant tooth size discrepancy more than 2SDs of Bolton's ABI and the visual judgment was 96.0% and a cut-off point of -0.12mm was obtained.

Conclusion

Bolton's analysis should be routinely performed in all orthodontic patients, and visual estimation of TSD would be suggested as a screening method in the first visit prior to measurements and set-ups.

Impact of different rectangular wires on torsional expression of different sizes of buccal tube

Background

Torsions in rectangular wires are the essential part of corrections in the finishing stage of treatment. Moreover the greatest amounts of torques are applied in the molar areas. a clinically effective moment is between 5 and 20 Nmm. In this study we have decided to evaluate the impact of different tube sizes and different dimensions of wires with different modulus of elasticities on the amount torsional bond strength of molar tubes.

Material and Methods

60 human impacted molar teeth were collected. A buccal tube was bonded on the buccal surface of all the samples by using light cured adhesive resin. After that, the teeth were mounted in a hard acrylic block. According to the size of buccal tube and the rectangular wires to be tested 4 groups will be designed. Torsional force was applied by instron machine. The torque angle at 5Nmm and at 20Nmm point will be calculated: which means, how many degrees of torque is required to reach the maximum 20Nmm moment from the minimum 5Nmm.One-way ANOVA was used to compare torque angle in all of the groups.

Results

The least amount of clinically significant angle was 2.2 ᵒ in the 0.017×0.025 SS and the largest amount of it was 23.7 ᵒ in the 0.017×0.025 TMA in 0.018×0.025 slot molar tube. But, this angle was 19.9 ᵒand 13.6 ᵒ in 0.019×0.025 SS and 0.019×0.025 TMA archwire in 0.022×0.028 molar tube.

Conclusions

The 0.017×0.025 SS archwire in 0.018×0.025 molar tube had the lowest clinically significant angle. The largest amount was seen in group 0.017×0.025 TMA in 0.018×0.025 slot molar tube.

Key words: Torsional efficacy, rectangular wires, buccal tubes, torque angle.

Impact of Nano Hydroxyapatite, Nano Silver Fluoride and Sodium Fluoride Varnish on Primary Teeth Enamel Remineralization: An In Vitro Study

Introduction

Dental caries is still prevailing worldwide, although different anti caries products have been introduced. Each remineralizing agent has its own shortcomings. Therefore, looking for new agents to have benefits of previous ones with lesser side effects is worthwhile.

Aim

To determine the remineralization ability of NaF varnish, nano-Hydroxyapatite Serum (n-HAP) and Nano Silver Fluoride (NSF) on enamel of primary anterior teeth.

Materials and Methods

Incipient caries were induced in primary sound anterior teeth by storing each specimen in demineralization solution for 72 hours. Then they were randomly divided into four groups of 15 samples each: (1) NaF varnish; (2) n-HAP repairing serum; (3) NSF and (4) no treatment (control). Surface Microhardness (SMH) was assessed with Vickers micro hardness tester before and after demineralization and after 10 days of pH-cycling. A total of 12 random specimens from groups 1 to 4 (3 random samples of each group) were examined by Atomic Force Microscopy (AFM). The SMH values were analysed with one-way and repeated measures ANOVA. Level of significance was set at p=0.05.

Results

Post lesion SMH values significantly decreased in all groups (p<0.001). Post treatment SMH values significantly increased in comparison to post lesion ones (p<0.001) except for control group which was not different statistically (p=0.86). The highest SMH values were observed in NSF group (mean 222.90 ± 28.79). Statistically significant differences were shown between all groups (p<0.05). However, NaF varnish and n-HAP groups were not statistically different (p=0.165). AFM images demonstrated protective layers in all treated groups.

Conclusion

The results of this in vitro study suggest that NSF could have the greatest remineralization efficacy. NaF varnish and n-HAP serum were similar in remineralizing initial caries. Future clinical studies are recommended for selection of the most appropriate remineralizing agent in primary teeth.

Prevalence and Characteristics of Developmental Dental Anomalies in Iranian Orofacial Cleft Patients

STATEMENT OF THE PROBLEM

Individuals with oral clefts exhibit considerably more dental anomalies than individuals without clefts. These problems could initially be among the symptoms of their disease and/or they may be the side effect of their treatments. Pushback palatoplasty could cause some interference during the development of teeth and result in tooth defects.

PURPOSE

The study was performed to assess the prevalence and characteristics of developmental dental anomalies in orofacial cleft patients who attended Shiraz Orthodontics Research Center-Cleft Lip and Palate Clinic. We managed to compare dental anomaly traits based on gender and cleft side.

MATERIALS AND METHOD

Eighty out of 121 cleft patients were included in this cross-sectional study. All the patients used pushback palatoplasty in their palate closure surgeries. Intraoral photographs, panoramic and intraoral radiographs, cone-beam computed tomography (CBCT) and dental and medical histories were examined and recorded by two observers. Data were analyzed using SPSS PC version 20.0. The differences in the side of cleft and dental anomalies were compared using the Mann-Whitney test.

RESULTS

The mean age of patients was 14.27 years (SD=5.06). The most frequent cleft type was unilateral cleft lip and palate (50%) followed by bilateral cleft lip and palate (43.75%), cleft palate (2.5%) and cleft lip (1.25%). Male predominance (70%) was observed. 92.5 percent had at least one developmental dental anomaly. The most prevalent anomalies were hypodontia (71.25%) followed by microdontia (30%), root dilacerations (21.25%) and supernumerary teeth (15%).

CONCLUSION

The most prevalent cleft types were unilateral and bilateral cleft lip and palate with male and left side predominance. Hypodontia, microdontia, dilacerations and supernumerary teeth were the most prevalent developmental dental anomalies among Iranian southwestern cleft patients. The surgical technique used to repair their cleft palate may have played a role in developmental dental defects.

Synergic effect of salivary pH baselines and low pH intakes on the force relaxation of orthodontic latex elastics

Background:

Latex elastics are still in common use due to their low cost and high flexibility to improve sagittal discrepancies or interdigitation of teeth. Mechanical properties of elastics are influenced by several environmental factors such as pH changes. This study evaluated similar latex elastics to define the influence of synergic effect of intermittent low pH and various baselines pH of saliva.

Materials and Methods:

Four groups of latex elastics (3-M Unitek, 3/16 inch) were tested (n = 15 in each group). Two groups of elastics were immersed in two tanks of artificial saliva with different pH levels of 7 and 5, and two groups were immersed in two tanks of artificial saliva with intermittent drop of pH to 4. The force was measured when the elastics were stretched to 25 mm. These measurements were taken in 0, 4, 8, 12, 24, 36, and 48 h for each group. Repeated measures analysis of variance (RMANOVA) and post-hoc Tukey's test were used to assess the findings. The level of significance was 0.05%.

Results:

The interaction between pH and time analyzed with RMANOVA showed no significant differences (P > 0.05) except in 36 h (P = 0.014). The Tukey's analysis showed that each comparison between any two groups did not indicate significant differences (P > 0.05) except between Groups 1 and 3 and between Groups 2 and 3 (P < 0.05).

Conclusion:

No significant correlation was seen between fluctuation of pH and force degradation in latex elastic band except in 36 h.

Stress distributions of a bracket type orthodontic miniscrew and the surrounding bone under moment loadings: Three-dimensional finite element analysis

Objectives:

To evaluate the effect of moments and the combination of forces and moments on the mechanical properties of a bracket type miniscrew, resembling engagement of a rectangular wire by three-dimensional (3D) finite element study.

Materials and Methods:

By solid work software (Dassaunlt systems solid works, concord, Mass), a 3D miniscrew model of 6, 8, 10 mm lengths was designed and inserted in the osseous block, consisted of the cortical, and cancellous bones. The stress distributions, maximum stresses, and deflections of the miniscrew were evaluated for all parts using ANSYS (Work Bench, 2014).

Results:

As the magnitudes of the load increased from 100 to 200, 400 and 800 grf-mm, the peak of stresses in the 6 mm long miniscrew were increased from 7.7 to 61.5 Mpa. The maximum values of Von Mises in the cancellous bone were tremendously lower in comparison to the cortical bone by one hundredth. As the length of the miniscrew in contact with the bone was increased, the amounts and patterns of stress distribution in the cortical bone and the miniscrew did not change significantly.

Conclusions:

As the moment magnitude increased, the pick stresses increased linearly. The existence of cancellous bone was not significantly responsible for the stress distribution. The pattern of stress distribution did not change by the length of the miniscrew.

Augmenting the bioactivity of polyetheretherketone using a novel accelerated neutral atom beam technique

Polyetheretherketone (PEEK) is an alternative to metallic implants in orthopedic applications; however, PEEK is bioinert and does not osteointegrate. In this study, an accelerated neutral atom beam technique (ANAB) was employed to improve the bioactivity of PEEK. The aim was to investigate the growth of human mesenchymal stem cells (hMSCs), human osteoblasts (hOB), and skin fibroblasts (BR3G) on PEEK and ANAB PEEK.

METHODS

The surface roughness and contact angle of PEEK and ANAB PEEK was measured. Cell metabolic activity, proliferation and alkaline phosphatase (ALP) was measured and cell attachment was determined by quantifying adhesion plaques with cells.

RESULTS

ANAB treatment increased the surface hydrophilicity [91.74 ± 4.80° (PEEK) vs. 74.82 ± 2.70° (ANAB PEEK), p < 0.001] but did not alter the surface roughness. Metabolic activity and proliferation for all cell types significantly increased on ANAB PEEK compared to PEEK (p < 0.05). Significantly increased cell attachment was measured on ANAB PEEK surfaces. MSCs seeded on ANAB PEEK in the presence of osteogenic media, expressed increased levels of ALP compared to untreated PEEK (p < 0.05) CONCLUSION: Our results demonstrated that ANAB treatment increased the cell attachment, metabolic activity, and proliferation on PEEK. ANAB treatment may improve the osteointegration of PEEK implants. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1438-1446, 2017.

Impact of nanohydroxyapatite on enamel surface roughness and color change after orthodontic debonding

Background

The aim of this prospective in vitro study was to evaluate the effect of nanohydroxyapatite (nanoHAP) serum on the enamel surface roughness and tooth color stability after orthodontic debonding procedure.

Methods

The crowns of 30 premolars were embedded in acrylic blocks with a 4 mm × 5-mm-sized window on the middle third of buccal surfaces. Primary roughness values were evaluated by an atomic force microscope (AFM). After bracket debonding, and polishing procedures, the second roughness parameters were recorded. Specimens were then randomly assigned to two equal groups. NanoHAP serum and HAP toothpaste were applied for 10 days in the first and second groups, respectively. Then, after the third AFM, initial color parameters were measured. Following 1-week immersion in the coffee solution, second color assessment was performed. The fourth AFM was registered after 2 months of aging process.

Results

All roughness parameters were elevated following debonding procedure. There was no statistically significant reduction in roughness parameters after 10 days of nanoHAP serum or HAP toothpaste application. Both groups showed significant color change after immersion in the coffee solution.

Conclusions

NanoHAP serum with the protocols used in this study could not restore enamel surfaces to their original condition.

Histological evaluation of two designs of shoulder surface replacement implants

AIMS

To assess the extent of osteointegration in two designs of shoulder resurfacing implants. Bony integration to the Copeland cylindrical central stem design and the Epoca RH conical-crown design were compared.

PATIENTS AND METHODS

Implants retrieved from six patients in each group were pair-matched. Mean time to revision surgery of Copeland implants was 37 months (standard deviation (sd) 23; 14 to 72) and Epoca RH 38 months (sd 28; 12 to 84). The mean age of patients investigated was 66 years (sd 4; 59 to 71) and 58 years (sd 17; 31 to 73) in the Copeland and Epoca RH groups respectively. None of these implants were revised for loosening.

RESULTS

Increased osteointegration was measured under the cup in the Copeland implant group with limited bone seen in direct contact with the central stem. Bone adjacent to the Epoca RH implants was more uniform.

CONCLUSION

This difference in the distribution of bone-implant contact and bone formation was attributed to the Epoca implant's conical crown, which is positioned in more dense peripheral bone. The use of a central stem may not be necessary provided there is adequate peripheral fixation within good quality humeral bone.

TAKE HOME MESSAGE

Poor osteointegration of cementless surface replacement shoulder prosthesis may be improved by implant design.

The Effects of Different Miniscrew Thread Designs and Force Directions on Stress Distribution by 3-dimensional Finite Element Analysis

STATEMENT OF THE PROBLEM

The use of miniscrew as an absolute anchorage device in clinical orthodontics is growing increasingly. Many attempts have been made to reduce the size, to improve the design, and to increase the stability of miniscrew.

PURPOSE

The purpose of this study was to determine the effects of different thread shapes and force directions of orthodontic miniscrew on stress distribution in the supporting bone structure.

MATERIALS AND METHOD

A three-dimensional finite element analysis was used. A 200-cN force in three angles (0°, 45°, and 90°) was applied on the head of the miniscrew. The stress distribution between twelve thread shapes was investigated as categorized in four main groups; buttress, reverse buttress, square, and V-shape.

RESULTS

Stress distribution was not significantly different among different thread shapes. The maximum amount of bone stress at force angles 0°, 45°, and 90° were 38.90, 30.57 and 6.62 MPa, respectively. Analyzing the von Mises stress values showed that in all models, the maximum stress was concentrated on the lowest diameter of the shank, especially the part that was in the soft tissue and cervical cortical bone regions.

CONCLUSION

There was no relation between thread shapes and von Mises stress distribution in the bone; however, different force angles could affect the von Mises stress in the bone and miniscrew.

A comparison of force decay: elastic chain or tie-back method?

AIM

To evaluate the amount of initial force and to compare the amount of force decay between the elastomeric chain and tie-back method over a period of time.

METHODS

Twenty five-unit elastomeric chains (15 mm) stretched 100%, and twenty elastic modules in tie-back method stretched twice their original diameter were held in place by a series of pins 30-mm apart in acrylic blocks. The blocks were stored in 37 °C distilled water. The force of all samples was measured at baseline, 24 and 48 hours, and once a week thereafter for 4 weeks with a force gauge. The groups were tested with a multivariate analysis of repeated measurement at the 95% confidence level.

RESULTS

The tie-back method with mean force of 577.50 grams (standard deviation [SD] 28.63) had a lower initial force than the elastomeric chain with mean force of 650.00 grams (SD 34.47). The elastomeric chain showed a substantial force decay of 355.50 grams (SD 53.2) at 24 hours, but the force decay in the tie-back method was less (mean 154 grams, SD 56.50). The force decay of the elastomeric chain and tie-back at 48 hours were 446.50 grams (SD 35.4) and 209 grams (SD 57.1), respectively. The difference between the force decay of the two groups at both 24 and 48 hours was statistically significant (P<.05).

CONCLUSION

Using the tie-back method of space closure, which has more appropriate initial force and slower force decay, may have a clinical value, approaching a more light and continued force. However, more studies are required to test these findings in vivo.