Effects of Maxillary Movements on Lips Following Orthognathic Surgery: A Retrospective Non-Randomized Clinical Trial

Introduction  Lips play a fundamental role in facial attractiveness and in decisions pertaining to orthognathic surgery. Objective  To assess the upper lip changes following Le Fort I osteotomy for maxillary advancement and/or impaction. Methods  In the present retrospective non-randomized clinical trial, we evaluated 3 groups of patients who underwent Le Fort I osteotomy of the maxilla. Group 1 (n = 35) underwent maxillary advancement, group 2 (n = 14), maxillary impaction, and group 3 (n = 11) was submitted to both maxillary advancement and impaction. The lip thickness of all patients was measured preoperatively, and the participants in each group were categorized into two subgroups: thin (< 12 mm) and thick (> 12 mm) lip. The primary (before orthognathic surgery) and final (after orthodontic bracket removal) lateral cephalograms of the patients were analyzed using the Dolphin software. Comparisons were made using the paired t -test and linear regression in the IBM SPSS Statistics for Windows software. Results  The length of the upper lip increased by 1 mm ( p  = 0.012) on average following maxillary advancement, and it decreased by 0.43 mm ( p  = 0.24) on average following maxillary impaction. In the maxillary advancement group, the change in angulation of the incisors predicted the incisal display ( p  = 0.03). In the maxillary impaction group, skeletal changes in the vertical dimension predicted changes in upper lip length ( p  = 0.033). Conclusions  Le Fort I osteotomy for maxillary advancement significantly increases the length of the upper lip. The assessment of lip thickness prior to surgery can help predict the postoperative results. Changing the angulation of the incisors can predict the incisal display. In maxillary impaction, skeletal changes in the vertical dimension can predict the changes in the length of the upper lip.

Comparative study of changes in the airway dimensions following the treatment of Class II malocclusion patients with the twin-block and Seifi appliances

BACKGROUND

Functional appliances are frequently used to stimulate mandibular growth in cases of Class II malocclusion with mandibular deficiency. Many studies have reported improved pharyngeal airway passage (PAP) dimensions following functional appliance therapy in children.

OBJECTIVES

The present study aimed to assess changes in the airway dimensions following the treatment of Class II malocclusion patients with the twin-block and Seifi appliances.

MATERIAL AND METHODS

Lateral cephalograms of 37 patients with Class II malocclusion and mandibular deficiency treated with the twin-block appliance (n = 20) or the Seifi appliance (n = 17) were assessed in this before-and-after study. The preoperative and postoperative lateral cephalograms were compared to determine changes in the airway dimensions at the level of the palatal plane (PP), the occlusal plane (OP) and the 2nd-4th cervical vertebrae (C2-C4) in the 2 groups. The results were analyzed with the t test and the one-way analysis of covariance (ANCOVA).

RESULTS

After treatment, significant changes occurred in the point A-nasion-point B (ANB) and sellanasion-point B (SNB) skeletal cephalometric indices in the twin-block appliance group, and in ANB, SNB and incisor-mandibular plane angle (IMPA) in the Seifi appliance group. The airway dimensions at the level of PP, OP and the 3rd cervical vertebra (C3) significantly increased postoperatively as compared to the baseline in the twin-block appliance group (p < 0.05). The increases in the airway dimensions at the level of PP and C3 in the twin-block appliance group were significantly greater than in the Seifi appliance group (p < 0.05).

CONCLUSIONS

The treatment of Class II Division I malocclusion with the twin-block appliance significantly increased the airway dimensions at the level of PP, OP and C3, whereas the Seifi appliance did not cause any significant changes in the airway dimensions.

Ideal Lifestyle to Have Healthy Lungs: Persian Medicine Viewpoint

Persian medicine introduces six essential principles to maintain health and improve the breathing of the patients with pulmonary diseases. Adherence to each of these principles plays an important role in having healthy lungs. The purpose of this study was to review the scientific evidence of the mentioned recommendations while discussing the Persian medicine recommendations. Accordingly, suggestions related to maintaining lung health were extracted from the main sources of Persian medicine. In addition, similar topics were searched in PubMed, Scopus, Google Scholar, Web of Science, and SID databases. Then, results were expressed separately in each aspect of the six essential principles. These recommendations which are the result of hundreds-of-years-experience of Iranian physicians could be useful; however, future experimental investigations are needed to approve their safety and efficacy along with the possible mechanisms of action.

Association between Lateral Cephalometric Changes in X-Y Coordinate System and Profile Changes among Skeletal Class III Patients after Orthognathic Surgery

BACKGROUND

Since aesthetic issues are the most important causes of referring skeletal class III patients to surgeons, investigating the impact of orthognathic surgeries on improving patient profiles increases the quality of treatment and quality of life.

METHODS

In a retrospective observational-analytical study, 25 patients older than 18 years with class III skeletal malocclusion who had gone under both orthodontic and double-jaw orthognathic treatment were enrolled. Cephalometric imaging interval was before and at least 6 months after surgery. By defining a number of points and coordinate axes (X-Y), a criterion for comparing hard and soft tissue changes was obtained. These measurements were coordinated, linear and angular. The quantitative data were compared with data obtained using the Likert Scale Questionnaire by means of electronic "Google Forms" that was completed by orthodontists (n=5) and maxillofacial surgeons (n=5) to rank improvement in post-surgical profiles for both cephalometry and photography from poor to pleasant. Spearman Correlation Analysis was conducted between the quantitative and qualitative data.

RESULTS

Vertical changes of point B and horizontal changes of point PNS showed correlation with improvement of patient profile. Changes in N-Pog line (R=-0.4), mandibular plane angle (R=-0.4) and nasolabial angle (NLA) (R=0.38) were significantly correlated with improvement of profiles.

CONCLUSION

In orthognathic double-jaw surgery on patients with skeletal Class III, forward movement of maxilla, upward positioning of mandible (decreasing anterior facial height), decreasing mandibular plane angle and increasing nasolabial angle would result in a better profile.

Shear bond strength of orthodontic brackets to porcelain surface using universal adhesive compared to conventional method

BACKGROUND

Considering the increase in demand for orthodontic treatment in adults, bracket bond to restored teeth is a clinical challenge. This study sought to compare the shear bond strength (SBS) of orthodontic brackets to feldspathic porcelain using universal adhesive and conventional adhesive with and without silane application.

MATERIALS AND METHODS

In this in vitro study Fifty-six feldspathic porcelain discs were roughened by bur, and 9.6% hydrofluoric acid was used for surface preparation. Samples were divided into the following four groups (n = 14): Group 1: universal adhesive, Group 2: universal adhesive/silane, Group 3: conventional adhesive, and Group 4: conventional adhesive/silane. Mandibular central incisor brackets were bonded, and SBS was measured by Instron^® machine. To assess the mode of failure, adhesive remnant index (ARI) score was determined. The data were analyzed using SPSS software and two-way ANOVA, Bonferroni test, and Kruskal-Wallis test (P < 0.05 considered significant).

RESULTS

The highest SBS was noted in the universal adhesive/silane group (12.7 MP) followed by conventional adhesive/silane (11.9 MP), conventional adhesive without silane (7.6 MP), and universal adhesive without silane (4.4 MP). In the absence of silane, the conventional adhesive yielded significantly higher SBS than universal adhesive (P = 0.03). In the presence of silane, the two adhesives showed SBS values significantly higher than the values obtained when silane was not applied, while the two adhesives were not significantly different in terms of SBS in the presence of silane (P = 0.53). Based on ARI score, there were statistically significant differences between Groups 1 and 4 (P = 0.00) and Groups 2 and 4 (P = 0.023).

CONCLUSION

Based on the current results, SBS of bracket to porcelain mainly depends on the use of silane rather than the type of adhesive. Both universal and conventional adhesives yield significantly higher SBS in the presence of silane compared to that in the absence of silane.

Shear Bond Strength of Orthodontic Brackets to Composite Restorations Using Universal Adhesive

STATEMENT OF THE PROBLEM

The dental adhesives may have the potential to increase the bond strength of orthodontic brackets to composite resin and it would be highly desirable if adequate bracket-composite bond strength could be yielded by using these adhesives without the need for surface roughening.

PURPOSE

The purpose of this study was to measure the shear bond strength (SBS) of metal brackets to composite restorations by use of a universal adhesive compared with a conventional adhesive.

MATERIALS AND METHOD

In this in vitro, experimental study, 45 composite discs measuring 6 mm in diameter and 4 mm in thickness were fabricated and assigned to three groups (n=15). In the group 1, discs were etched with 37% phosphoric acid for 15 seconds and Scotchbond Universal was then applied. Discs were roughened by diamond bur in the group 2 and were subjected to the application of Scotchbond Universal. In the group 3, conventional adhesive (Single Bond 2) was applied after roughening the discs by diamond bur. Metal brackets were then bonded to discs and after thermocycling, the SBS was measured by an Instron machine. The mode of failure and adhesive remnant index (ARI) score were determined using stereomicroscope. Data were analyzed by SPSS version 18, one-way ANOVA, and the Kruskal Wallis test.

RESULTS

The surface roughening plus universal adhesive group showed the highest SBS (11.90 MPa) but according to one-way ANOVA, the difference in this regard among the three groups was not statistically significant (p= 0.94). Most samples showed ARI score of 4.

CONCLUSION

Universal adhesive can provide sufficient bond strength as high as that provided by conventional adhesives for orthodontic bracket bonding to composite restorations even in absence of surface roughening by bur.

Prevention of white spot lesions using three remineralizing agents: An in vitro comparative study

Background. Enamel demineralization around orthodontic brackets is an important clinical problem. This study sought to compare the efficacy of sodium fluoride (NaF), casein phosphopeptide amorphous calcium phosphate fluoride (CPP-ACP-F; MI Paste Plus) and a water-based cream (Remin Pro), which contains hydroxyapatite and fluoride for prevention of enamel demineralization.

Methods. Fifty-six sound human premolars extracted for orthodontic purposes were collected. After cleaning, the crowns were mounted in acrylic resin and all the surfaces were coated with nail varnish except for a 3×4-mm window on the buccal surface. The samples were randomly divided into four groups of 14 and subjected to pH cycling for 14 days, during which the teeth were immersed in artificial saliva for 21 hours and in demineralizing agent for three hours daily. Before transferring the samples from the saliva to the demineralizing solution, the remineralizing agent (0.05% NaF, MI Paste Plus or Remin Pro Paste, depending on the group) was applied on the samples once a day for five minutes. No remineralizing agent was used in the control group. Surface microhardness of samples was measured by Vickers microhardness tester at baseline and after the intervention. The data were analyzed using one-way ANOVA, ANCOVA, Bonferroni test and Tukey test. Statistical significance was set at P<0.05.

Results. The mean microhardness was significantly different between the test and control groups (P<0.0001). Other differences were not significantly different (P>0.05).

Conclusion. The results showed that 0.05% NaF was more efficient than Remin Pro and MI Paste Plus for prevention of white spot lesions (WSLs). Remin Pro and MI Paste Plus were not significantly difference from the control group in this regard.

Cephalometric changes in nasopharyngeal area after anterior maxillary segmental distraction versus Le Fort I osteotomy in patients with cleft lip and palate

OBJECTIVE

The present study was designed to compare the effects of two surgical methods, anterior maxillary segmental distraction (AMSD) versus conventional Le Fort I osteotomy, on cephalometric changes of velopharyngeal area of patients with cleft lip and palate.

MATERIALS AND METHODS

This study was conducted on 20 CLP in two groups. The first group had classic Le Fort I maxillary advancement and the second group had AMSD with a modified hyrax as an intraoral tooth-borne distractor. In the second group, 1 week after the surgery, activation of hyrax screw was started with the rate of 2 times a day for about 10 days. Initial and final lateral cephalograms were traced and analyzed by OrthoSurgerX software.

RESULTS

The changes in variables evaluating velopharyngeal status showed a significant difference between the two groups. In Group A (conventional), the mean of nasopharyngeal area and Nasopharynx floor length showed a significant increase (P < 0.05) after the surgery, while in Group B (DO), the trend of changes was vice-versa. The changes in SNA, overjet, and soft-tissue convexity were similar in both groups.

CONCLUSION

AMSD can improve facial profile, almost similar to the conventional Le Fort I advancement, while there is a significant decrease in nasopharyngeal; hereby there is no increase in the velopharyngeal sphincter.

Ion Release and Galvanic Corrosion of Different Orthodontic Brackets and Wires in Artificial Saliva

INTRODUCTION

To investigate the galvanic corrosion of brackets manufactured by four different companies coupled with stainless steel (SS) or nickel-titanium (NiTi) wires in an artificial saliva solution.

MATERIALS AND METHODS

A total of 24 mandibular central incisor Roth brackets of four different manufacturers (American Orthodontics, Dentaurum, Shinye, ORJ) were used in this experimental study. These brackets were immersed in artificial saliva along with SS or NiTi orthodontic wires (0.016'', round) for 28 days. The electric potential difference of each bracket/ wire coupled with a saturated calomel reference electrode was measured via a voltmeter and recorded constantly. Corrosion rate (CR) was calculated, and release of ions was measured with an atomic absorption spectrometer. Stereomicroscope was used to evaluate all samples. Then, samples with corrosion were further assessed by scanning electron microscope and energy-dispersive X-ray spectroscopy. Two-way analysis of variance was used to analyze data.

RESULTS

Among ions evaluated, release of nickel ions from Shinye brackets was significantly higher than that of other brackets. The mean potential difference was significantly lower in specimens containing a couple of Shinye brackets and SS wire compared with other specimens. No significant difference was observed in the mean CR of various groups (p > 0.05). Microscopic evaluation showed corrosion in two samples only: Shinye bracket coupled with SS wire and American Orthodontics bracket coupled with NiTi wire.

CONCLUSION

Shinye brackets coupled with SS wire showed more susceptibility to galvanic corrosion. There were no significant differences among specimens in terms of the CR or released ions except the release of Ni ions, which was higher in Shinye brackets.

The Effect of Root Coating with Titanium on Prevention of Root Resorption in Avulsed Teeth: An Animal Study

Introduction:

Tooth avulsion is a real dental emergency. If immediate replantation is not performed, the avulsed tooth may be lost due to inflammatory or replacement resorption. This animal study aimed to evaluate the bone response to the titanium coating of the root surface as an artificial barrier, and prevention of resorption of avulsed teeth.

Methods and Materials:

This experimental study was conducted on four male dogs. The dogs were randomly divided into two groups for assessment at two and eight weeks. Four teeth were extracted in each animal. The root surfaces of the test group were coated with a titanium layer using the Electron Beam Deposition system. After 24 h, replantation of the teeth was performed. Two animals were sacrificed after two weeks and the remaining dogs were killed after eight weeks. The presence of inflammation, inflammatory resorption, replacement resorption, periodontal regeneration, periapical granuloma and ankylosis were evaluated through histological analyses.

Results:

Inflammatory root resorption was not present in any tooth except one tooth in the coated group after eight weeks. Replacement resorption was noted just in three of the non-coated teeth after two weeks and two teeth after eight weeks. The McNemar's test revealed that the frequency of replacement resorption in the non-coated group was significantly higher than the coated group (P=0.031).

Conclusion:

Based on the results of this study, it seems that coating the root surfaces of avulsed teeth with titanium may control the replacement root resorption.

Gulossectomy and Skeletal Anchorage as Aajuncts to Orthodontic Correction of a Severe Open Bite Case

Etiology of open bite malocclusion is multifactorial; therefore, elimination of the main etiologic factor is the key for successful treatment. Tongue size and posture can cause open bite; thus, glossectomy is one of the treatment choices in severe cases. A 19 year old girl with a chief complaint of extra-large tongue and anterior open bite due to hemangioma was referred to us. Hemangioma removal and partial glossectomy were performed. With no other intervention, the anterior open bite decreased 10 millimeters within 3 years. Since the patient refused orthognathic surgery, the remaining malocclusion was resolved by orthodontic treatment using skeletal anchorage.

Galvanic Corrosion of and Ion Release from Various Orthodontic Brackets and Wires in a Fluoride-containing Mouthwash

Background and aims. This study compared the galvanic corrosion of orthodontic wires and brackets from various manufacturers following exposure to a fluoride mouthwash. Materials and methods. This study was conducted on 24 lower central incisor 0.022" Roth brackets of four different commercially available brands (Dentaurum, American Orthodontics, ORJ, Shinye). These brackets along with stainless steel (SS) or nickel-titanium (NiTi) orthodontic wires (0.016", round) were immersed in Oral-B mouthwash containing 0.05% sodium fluoride for 28 days. The electric potential (EP) difference of each bracket-wire couple was measured with a Saturated Calomel Reference Electrode (Ag/AgCl saturated with KCl) via a voltmeter. The ions released in the electrolyte weremeasured with an atomic absorption spectrometer. All the specimens were assessed under a stereomicroscope and specimens with corrosion were analyzed with scanning electron microscopy (SEM). Data were analyzed using ANOVA. Results. The copper ions released from specimens with NiTi wire were greater than those of samples containing SS wire. ORJ brackets released more Cu ions than other samples. The Ni ions released from Shinye brackets were significantly more than those of other specimens (P < 0.05). Corrosion rate of brackets coupled with NiTi wires was higher than that of brackets coupled with SS wires. Light and electron microscopic observations showed greater corrosion of ORJ brackets. Conclusion. In fluoride mouthwash, Shinye and ORJ brackets exhibited greater corrosion than Dentaurum and American Orthodontics brackets. Stainless steel brackets used with NiTi wires showed greater corrosion and thus caution is recommended when using them.

Distraction osteogenesis for cleft palate closure: A finite element analysis

BACKGROUND

Current methods of closure of the cleft palate result in the formation of scars and impairment of growth. Distraction osteogenesis (DO) might be an effective means to repair or at least reduce the size of wide clefts. This study investigates the biomechanical aspects of this process.

MATERIALS AND METHODS

DO simulation was applied to reduce the size of a unilateral hard palate cleft on a three-dimensional (3D) model of the maxilla. For the position of osteotomy lines, two different models were assumed, with the osteotomy line on the affected side in model A and on the intact side in model B. In each model, DO screws were placed on two different positions, anteriorly (models A1 and B1) and posteriorly (models A2 and B2). Displacement pattern of the bony island in each of the four models, reaction forces at DO locations, and von Mises stress were estimated. Mesh generation and data processing were carried out in the 3D finite element analysis package (ABAQUS V6.7-1; Simulia Corp., Providence, RI, USA).

RESULTS

In model B2, the island moved almost evenly, assuring a more complete closure of the cleft. The most uniform stress distribution was found in model B1.

CONCLUSION

The results suggest that the best positions for the DO screw and the osteotomy line for closure of the cleft palate are posteriorly and on the intact side, respectively.

Fracture characteristics of fibre reinforced composite bars used to provide rigid orthodontic dental segments

BACKGROUND

Fibre reinforced composites (FRC) can be used to join teeth as a rigid unit for anchorage purposes and/or for tooth movement. The utility of FRCs for these applications depends on the fracture characteristics and durability of the material under masticatory loads.

AIMS

To evaluate the effect of simulated masticatory loads on the fracture characteristics of FRC bars joining two bicuspids.

METHODS

Eighty extracted maxillary bicuspids were used. Pairs of bicuspids were joined with FRC bars on the buccal surfaces. The specimens were divided into two equal groups. In group A the fracture loads of the FRC bars were measured, and in group B the specimens were placed in a simulator and subjected to 4x10(5) chewing cycles, simulating a 2-year period of mastication. At the conclusion of this test the fracture loads of the FRC bars were measured in the intact specimens. All specimens were examined stereomicroscopically to determine the fracture pattern.

RESULTS

There were no bond failures in group B during the simulated masticatory forces. The mean fracture loads in groups A and B were 195.8 N and 190.6 N, respectively. Stereomicroscopic examination showed that most fractures occurred at the enamel-composite interfaces in both groups. There were no significant differences between the groups in the fracture loads and fracture patterns.

CONCLUSIONS

Fibre reinforced composite bars bonded to bicuspids had sufficient durability to withstand the loads simulating a 2-year period of function. The fracture loads and fracture patterns of the FRC bars were not affected by the loads exerted by the simulator.