A comparison of treatment impacts between Invisalign aligner and fixed appliance therapy during the first week of treatment

Short-Term Effect of Orthodontic Treatment with Clear Aligners on Pain and sEMG Activity of Masticatory Muscles

Background and objectives: The aim of this study is to evaluate mandibular elevator muscles activity and pain on palpation in the early stages of orthodontic treatment with clear aligners using surface electromyography (sEMG). Materials and methods: Surface electromyography (sEMG) activity and pain level on muscle palpation of masseter and anterior temporalis muscles were recorded in a sample of 16 adult subjects (aged 18–32 years; mean 22.5 +/− 3.5 SD) undergoing orthodontic treatment with clear aligners before the treatment (T0), after 1 month of treatment (two clear aligners) (T1), and after 3 months of treatment (T2) (six clear aligners). A chi-square test for nominal data, a Friedman test, and a Wilcoxon-signed rank test as post hoc analysis were applied. Results: No statistically significant differences in muscular pain were observed. At T1, the sEMG activity of masseter muscles at mandibular rest position showed a statistically significant reduction, but after 3 months (T2), the data appeared similar to T0 (p = 0.03 and p = 0.02). Conclusions: During the treatment with clear aligners, subjects could experience an initial reduction in the masseter basal activity after 1 month of treatment. This effect tends to decrease to baseline levels after 3 months of therapy.

Class II subdivision with skeletal transverse maxillary deficit treated by single-sitting bone-borne appliance

This case report describes orthodontic treatment including both skeletal maxillary expansion and unilateral distalization by means of a single bone-borne appliance followed by clear aligner therapy in a young adult patient. A surgical guide was digitally designed and three-dimensionally printed to facilitate the placement of four miniscrews in the palatal vault. The miniscrews were fitted and the bone-borne appliance was delivered in a single clinical appointment. The postexpansion photographic records and models demonstrate the opening of the palatal median suture, the pure skeletal expansion, and the resolution of the left crossbite after 40 activations. Specifically, left molar Class I was obtained in about 5 months without any loss of anterior anchorage, and the subsequent aligner phase achieved all of the objectives established in the treatment plan. This case report shows clearly how careful digital planning of miniscrew insertion and the delivery of a pure bone-borne appliance in a single sitting enabled good clinical outcomes to be achieved in an acceptable timeframe, without side effects, even in a young adult patient.

Risk Factors of Composite Attachment Loss in Orthodontic Patients during Orthodontic Clear Aligner Therapy: A Prospective Study

BACKGROUND

The composite attachment loss during orthodontic clear aligner therapy is an adverse event that commonly happens in our daily practice. However, there is a lack of related statistical analysis and studies analyzing the related risk factors. Therefore, the aim of this study is to assess the incidence of attachment loss during orthodontic clear aligner therapy and to identify rick factors that may predict such event.

MATERIALS AND METHODS

The demographics and clinical variables of 94 patients undergoing clear aligner therapy (27 males and 67 females; average age: 27.60 ± 0.86 years) were recorded. Both patient-related and tooth-related attachment loss was recorded. The chi-squared test and logistic regressive analysis were applied to identify the potential risk factors. SPSS for Mac (version 23.0, IBM, USA) was used for statistical analyses. P < 0.05 was considered statistically significant.

RESULTS

Our study suggested that the risk factors for attachment loss include frequent aligner removal (≥ 5 times a day) (losing rate = 60.0%, P = 0.005), aligner wear time less than 18 hours a day (losing rate = 50.8%, P = 0.014), eating without aligners inserted (losing rate = 47.9%, P = 0.034), utilizing aligner tray seaters (losing rate = 48.2%, P = 0.006), and unilateral mastication (losing rate = 52.1%, P = 0.002). The multivariable logistic regression analysis indicates that aligner wear time less than 18 hours a day (P = 0.020, B = 0.925), using aligner tray seaters (P = 0.007, B = 1.168), and unilateral mastication (P = 0.034, B = -0.458) were considered independent factors that can predict the composite attachment loss in orthodontic clear aligner therapy.

CONCLUSION

Wearing aligner less than 18 hours a day, using aligner tray seaters, and unilateral mastication may contribute to increased incidence of composite attachment loss during orthodontic clear aligner therapy.

The effect of vestibular, lingual, and aligner appliances on the quality of life of adult patients during the initial stages of orthodontic treatment

Background

Patient quality of life (QoL) during orthodontic treatment is an important consideration that requires greater academic investigation as greater focus is placed on enhancing patient experience. Quality of life (QoL) was assessed in three orthodontic appliance groups, i.e., vestibular, lingual, and aligners during the initial stages of treatment. The sample was comprised of 117 adult patient-subjects distributed into 3 groups: vestibular (n = 41), lingual (n = 37), and aligner (n = 39). A WHOQOL-BREF questionnaire surveyed four domains (physical health, psychological health, social relationships, and environment).

Results

Mean scores for domain 1, physical health, showed that the aligner group (28.1) had significantly greater scores than that of the vestibular (22.7) or lingual (22) groups. Domain 2, psychological health, demonstrated significant differences (P < 0.001) between all groups, with the aligner group scoring the highest (23.2), followed by the lingual (18.4) and vestibular (15.2) groups. Domain 3, social relationship, showed that aligner (10.9) and lingual (10.2) scores were significantly greater (P < 0.001) than those of the vestibular group (7.8). Domain 4, environment, displayed significant differences between all groups, with the aligner group scoring highest (32.1), followed by the lingual group (29.3), and lastly the vestibular group (26.4). Overall, the highest mean score was obtained by the aligner group (23.1) and the lowest mean score was by the vestibular group (18). The mean domain scores for all three groups were significantly different (P ≤ 0.005) from each other (Table 2).

Conclusions

Overall, patients undergoing Aligner therapy reported the overall highest QoL scores, followed by lingual and vestibular groups.

Oral Impacts Experienced by Orthodontic Patients Undergoing Fixed or Removable Appliances Therapy in Saudi Arabia: A Cross-Sectional Study

PURPOSE

The objective of this study is to compare the orthodontic patient's experiences with removable and fixed orthodontic appliances on daily activities, food consumption, and oral symptoms in Riyadh city, Saudi Arabia.

METHODS

This was a cross-sectional observational study carried out among orthodontic patients. A total of 150 adult patients, including 118 in the fixed orthodontic appliance group and 32 in the removable (Invisalign) orthodontic group, who met the inclusion criteria completed a validated and self-administered questionnaire. In addition, the study participants reported their experience in terms of daily routine, food consumption, and oral symptoms one week after appliance activation. Data were analyzed using the chi-square test and Fisher's exact tests for the categorical variables. In addition, Mann-Whitney U, Kruskal-Wallis, and Spearman's tests were also applied to the data.

RESULTS

The fixed orthodontic patients compared to the removable orthodontic cases showed significantly higher difficulty in sleeping (1.28±1.10 vs 0.94±0.88, p=0.024), sores on the tongue (0.97±1.00 vs 0.56±0.76, p=0.042) and cheeks (1.20±1.11 vs 0.72±0.81, p=0.027), and the presence of food debris under the appliance (1.53±1.16 vs.1.00±0.95, p=0.021). Moreover, the oral health impact score showed a significant positive correlation with the duration of the orthodontic treatment (r=0.339, p<0.001) and pain intensity (r=0.309, p<0.001).

CONCLUSION

The fixed orthodontic treatment compared to removable orthodontic treatment resulted in more severe pain, sleeping difficulty, sores on the tongue and cheeks, and food impaction after one week of appliance activation.

Pressure Differences from Clear Aligner Movements Assessed by Pressure Sensors

OBJECTIVES

In this study, a clear aligner was moved at intervals of 0.25 mm and pressure variations were assessed using a sensor.

METHODS

The model used for producing the clear aligner was created using a 3-dimensional printer. A clear, circular thermoplastic of 0.75 mm thickness was used for making the clear aligner using the vacuum forming method. A pressure sensor was used to assess the pressure in the device, and the variation in the sheet pressure was statistically analyzed tooth movement using the clear aligner, moving at an interval of 0.25 mm, is recommended.

RESULTS

The results of pressure sensor assessment showed that the pressure of the devices with 0.25 mm and 1.00 mm movements was identical to that of the device with 0 mm movement. In other words, the pressure sensor could not distinguish the pressure of devices that moved 0.25 mm and 1.00 mm.

CONCLUSIONS

This experiment demonstrated that a movement of more than 0.50 mm is needed to apply the appropriate pressures needed for orthodontics in a clear polymer sheet.

Evaluation of masticatory muscle response to clear aligner therapy using ambulatory electromyographic recording

INTRODUCTION

Patients undergoing clear aligner therapy (CAT) report muscle tenderness and produce wear facets on their aligner trays. However, little is known about the masticatory muscle response to clear aligners. Here, we measured the activity of the masseter during CAT using ambulatory electromyography. We also explored whether psychological traits modulate the masticatory muscle response to CAT.

METHODS

Using portable data loggers, we recorded the electromyographic (EMG) activity in the right masseter muscle of 17 healthy adults without temporomandibular disorder (16 females, 1 male; mean age ± standard deviation, 35.3 ± 17.6 years) commencing treatment with CAT over 4 weeks, under the following conditions: week 1 without aligners (baseline), week 2 with a passive aligner (dummy), week 3 with their first active aligner (active1), and week 4 with their second active aligner (active2). We used a mixed-effect model to test differences in EMG activity over the 4-weeks and a general linear model to test the effect of psychological traits on EMG activity.

RESULTS

The EMG activity of the masseter increased significantly with aligners compared with baseline. The largest relative increase in EMG activity was seen during the dummy (152%; P <0.001) and active1 (155%; P <0.001) stages. During active2, the activity of the masseter decreased significantly toward baseline levels. Participants' trait anxiety was positively associated with increases in EMG activity (P = 0.027).

CONCLUSIONS

CAT is associated with a transient increase in masticatory muscle activity, possibly because of an increase in wake-time parafunctional tooth clenching. Temporomandibular disorder-free patients adapt well to CAT as the masticatory muscle activity decreases toward baseline levels after 2 weeks.

Relationship between oral health impacts and personality profiles among orthodontic patients treated with Invisalign clear aligners

This within subject clinical experiment assessed oral health impacts before and after Invisalign orthodontic treatment and their relationships with personality characteristics. 50 patients (26 females and 24 males; mean age = 27.62 ± 8.25 years, SE = 1.17, 95% CI = 24.71–29.89 years) were assessed before and after treatment with Invisalign orthodontic treatment. Treatment clinical success was evaluated according defined clinical guidelines. Oral health impacts before and after Invisalign orthodontic treatment were measured via the Oral Health Impact Profile (OHIP). Personality features were measured via the NEO Five-Factor Inventory (NEO-FFI). Probability of α = .05 was utilized to identify significant findings. Females scored less OHIP scores after treatment (had less negative impacts) in comparison to baseline OHIP scores (t = 3.782, df = 25, P = .001, 95% CI of mean difference = 2.750–9.327). Among males, openness scores (R² = .911, B = 5.235, 95% CI for B = 0.062–10.407, t = 2.601, P = .048) were able to predict OHIP scores before treatment; meanwhile, extraversion (R² = .959, B = − 8.224, 95% CI for B = − 14.605–1.843, t = − 3.313, P = .021), openness (R² = .959, B = 21.795, 95% CI for B = 10.737–32.853, t = 5.067, P = .004), and conscientiousness (R² = .959, B = 10.293, 95% CI for B = 4.796–15.790, t = 4.813, P = .005) scores were useful to predict OHIP scores after treatment (R² = .959, P < .05). NEO-FFI scores were not useful to predict OHIP scores before or after treatment among females (P > .05). These findings demonstrate that oral health impacts of Invisalign orthodontic treatment and personality profiles contribution to oral health impacts were different between genders.

Evaluation of pain intensity in patients treated with aligners and conventional fixed appliances: Randomized clinical trial

OBJECTIVE

This randomized clinical trial aimed to compare the pain intensity in patients treated with orthodontic aligners and conventional fixed appliances.

SETTING AND SAMPLE POPULATION

This study was a randomized clinical trial. The sample comprised 39 patients randomly allocated into 2 groups: OA (orthodontic aligners, n = 20) and FA (Fixed Appliance, n = 19).

MATERIAL AND METHODS

The pain intensity was measured by the visual analogue scale (VAS) in the following periods: T0 (baseline), T1 (seven days after appliance placement) and seven days after each return on the first (T2), third (T3) and sixth (T4) months. The following variables were also investigated in the baseline: conditioned pain modulation, anxiety levels, hypervigilance and catastrophizing. The VAS measurements between groups were compared by the Mann-Whitney test. Comparisons between periods within each group were performed by the Friedman test. Data regarding catastrophizing and hypervigilance were compared by the t test. All tests were applied at a significance level of 5%, with 95% confidence interval.

RESULTS

Both groups presented similar levels of anxiety, hypervigilance, catastrophizing and conditioned pain modulation. Both groups did not differ concerning the pain intensity in all periods. The intragroup evaluation revealed statistical differences between days in the FA group at all moments evaluated, for the OA group, similar findings between days were found for the T1 evaluation; however, at the 6-month period (T4), the pain levels varied over these days without statistical difference. Higher levels of pain were observed in the first seven days after appliance placement.

CONCLUSION

The pain intensity, usually mild, was not influenced by the appliance design, although different patterns of reported pain seem to occur between groups.

Indication of clear aligners in the early treatment of anterior crossbite: a case series

Introduction:

Anterior crossbite (AC) is defined as a reverse sagittal relationship between maxillary and mandibular incisors. According to an evidence-based orthodontic triage, the treatment need of AC is indicated if any occlusal interference is forcing the mandible towards a Class III growth pattern. Removable and fixed appliances have been suggested to correct AC.

Objective:

The present report aims at presenting the benefits of an alternative therapy for the early treatment of anterior crossbite using clear aligners.

Methods:

Two cases of anterior crossbite corrected using clear aligners in 8-years-old children are presented.

Results:

In both cases, AC was successfully corrected within 5 months. At the end of the treatment, overjet and overbite were corrected. No major discomfort or speech impairment was noticed by the parents.

Conclusions:

Due to the perceived shortcomings of alternative approaches, the use of clear aligners for correcting AC in mixed dentition should be considered as a comfortable and well tolerated appliance for young patients.

Clear aligner hybrid approach: A case report

INTRODUCTION

This case demonstrates that hybrid application of clear aligners can be a rational and efficient approach for treating malocclusions, as compared with a clear aligner therapy alone option in which the magnitude of some movements would require a higher number of aligners and likely further refinement.

TREATMENT PLAN AND PROGRESS

After a first successful orthopedic phase face mask + rapid maxillary expansion (FM + RME), a diagnostic digital setup of the second orthodontic treatment phase was performed, opting for an esthetic approach to make the treatment as fast and efficient as possible. After positioning lingual tubes on both arches, digital models were obtained and lingual archwires, passing through the previously positioned tubes, were simulated digitally. Then, a virtual setup comprising 10 steps for both arches was planned. Aligners enveloped fixed partial lingual appliances, improving patient comfort and efficiency of overall treatment. Aligners were changed every 7 days and the second phase of treatment was finished in 10 weeks with good occlusion and alignment in both arches. The entire treatment of the Class III patient was completed in 13 months of active therapy.

CONCLUSION

Combining clear aligner therapy and fixed lingual appliance is an esthetic means of treating malocclusions in a shorter treatment time with low costs and high efficiency.

Pain and Oral-Health-Related Quality of Life in Orthodontic Patients During Initial Therapy with Conventional, Low-Friction, and Lingual Brackets and Aligners (Invisalign): A Prospective Clinical Study

The aim of this study was to compare pain and its relationship with the oral quality of life of patients with different types of orthodontic appliances: conventional and conventional low-friction brackets, lingual brackets, and aligners. A prospective clinical study was carried out with a sample size of 120 patients (54 men, 66 women) divided into 4 groups of 30 patients each. The modified McGill questionnaire was used to measure pain at 4, 8, and 24 h and 2, 3, 4, 5, 6, and 7 days after the start of treatment, and the Oral Health Impact Profile-14 (OHIP-14) questionnaire was used to measure the oral-health-related quality of life (OHRQoL) in the first month of treatment. The maximum peak of pain was obtained between 24 and 48 h of treatment. It was found that patients in the lingual orthodontic group described lower levels of pain at all times analyzed, and their scores in the total OHIP-14 indicated less impact on their oral quality of life (1.3 ± 1.2, p < 0.01) compared with the other groups analyzed. There was little difference with the aligners group (Invisalign) (1.7 ± 1.9, p < 0.01). The technique used influences the pain and quality of life of patients at the start of orthodontic treatment.

Has Invisalign improved? A prospective follow-up study on the efficacy of tooth movement with Invisalign

INTRODUCTION

The purpose of this research was to provide an update on the accuracy of tooth movement with Invisalign (Align Technology, Santa Clara, Calif).

METHODS

This prospective clinical study included 38 patients treated with Invisalign Full or Invisalign Teen. All teeth, from the central incisor to the second molar, were measured on digital models created from intraoral scans. Predicted values were determined by superimposing the initial and final ClinCheck models, and achieved values were determined by superimposing the initial ClinCheck models and the digital models from the posttreatment scans. Individual teeth were superimposed with a best-fit analysis and measured using Compare software (version 8.1; GeoDigm, Falcon Heights, Minn). The types of tooth movements studied were a mesial-distal crown tip, buccal-lingual crown tip, extrusion, intrusion, and mesial-distal rotation.

RESULTS

The mean accuracy of Invisalign for all tooth movements was 50%. The highest overall accuracy was achieved with a buccal-lingual crown tip (56%), whereas the lowest overall accuracy occurred with rotation (46%). The accuracies for mesial rotation of the mandibular first molar (28%), distal rotation of the maxillary canine (37%), and intrusion of the mandibular incisors (35%) were particularly low.

CONCLUSIONS

There was a marked improvement in the overall accuracy; however, the strengths and weaknesses of tooth movement with Invisalign remained relatively the same.

Mechanical Properties of Thermoplastic Polymers for Aligner Manufacturing: In Vitro Study

The use of metal-free thermoplastic materials plays a key role in the orthodontic digital workflow due to the increasing demand for clear aligner treatments. Three thermoplastic polymers commonly used to fabricate clear aligners, namely Duran^®, Biolon^® and Zendura^®, were investigated to evaluate the effect of thermoforming (T.), storage in artificial saliva (S.A.S.) and their combination on their mechanical properties. Elastic modulus and yield stress of the specimens were characterized. Each material was characterized for each condition through tensile tests (ISO527-1). The results showed that thermoforming does not lead to a significant decrease in yield stress, except for Zendura^® that showed about a 30% decrease. An increase of the elastic modulus of Duran^® and Zendura^®, instead, was observed after thermoforming. The same increase was noticed for the yield stress of Duran^®. For S.A.S. specimens, the elastic modulus generally decreases compared to supplier condition (A.S.) and simply thermoformed material. A decrease of yield stress, instead, is significant for Zendura^®. The results demonstrated that the impact of the operating conditions on the mechanical properties can vary according to the specific polymer. To design reliable and effective orthodontic treatments, the materials should be selected after their mechanical properties are characterized in the simulated intraoral environment.

ATR-FTIR Analysis and One-Week Stress Relaxation of Four Orthodontic Aligner Materials

The aim of this study was to estimate possible differences in the chemical composition and relaxation of orthodontic aligner materials. Four commercially available thermoplastic materials CAM (Scheu-Dental, Iserlohn, Germany), COP (Essix, Dentsply Raintree Essix Sarasota,FL, USA), DUR (Great Lakes Dental Technologies, Tonawanda, NY) and ERK (Erkodent Erich Kopp, Pfalzgrafenweiler Germany) were included in this study. Rectangular strips from each material were prepared according to the manufacturer's instructions and subjected to attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and stress relaxation characterization. The reduction in applied stress (RAS) after one week was estimated and statistically analyzed by one-way ANOVA at the 0.05 level of significance. All specimens were subjected to optical microscopy before and after stress relaxation testing under transmittance polarized illumination. ATR-FTIR microscopy revealed that all materials are made of polyethylene terephthalate glycol (PETG) while no significant differences were identified in RAS values among materials tested, which ranged from 6%-10% (p ≥ 0.05). All samples illustrated the developments of shear bands during relaxation testing according to optical microscopy findings. The tested materials illustrated similar chemical composition and relaxation behavior and thus no differences in their clinical efficacy are anticipated.

Comparison of pain levels in patients treated with 3 different orthodontic appliances - a randomized trial

Background and aims

To compare pain levels experienced during initial alignment with three different orthodontic appliance types and to correlate pain with male and female differences, if any.

Methods

A prospective, randomized 3-arm parallel trial allocated 36 adult orthodontic patients into three appliance groups: MBT 0.022" slot (Mini Twin, Ormco, Glendora, USA), self ligating 0.022" slot Damon 3MX (Ormco, Glendora, USA) and clear aligners (Smile align, Mumbai, India). The level of discomfort was assessed through a questionnaire based on the visual analogue scale at four hours, twenty four hours, third and seventh day after appliance placement.

Results

Patients treated with clear aligners reported less pain than patients treated with conventional and self ligating fixed appliances. Patients treated with MBT conventional appliances showed greater pain levels than Damon appliances. A significantly higher visual analogue scale score was observed at 24 hours and the least visual analogue scale scores on the seventh day post appliance placement.

Conclusion

During the first week of orthodontic treatment, patients treated with clear aligners reported lower pain than those treated with conventional and self-ligating appliances.

Pain level between clear aligners and fixed appliances: a systematic review

OBJECTIVES

To assess if there is any difference in pain levels between orthodontic treatment with clear aligners or fixed appliances.

MATERIALS AND METHODS

An electronic search was completed in PubMed, The Cochrane Database, Web of Science, Scopus, Lilacs, Google Scholar, Clinical Trials, and OpenGrey databases without any restrictions until February 2019. All comparative study types contrasting pain levels between clear aligners and fixed appliances were included. The risk of bias (RoB) was assessed using the Newcastle-Ottawa Scale, ROBINS-I-Tool, or ROB 2.0 according to the study design. The level of evidence was assessed through the GRADE tool.

RESULTS

After removal of duplicates, exclusion by title and abstract, and reading the full text, only seven articles were included. Five were prospective non-randomized clinical trials (CCT), one was a cross-sectional study, and one was a randomized clinical trial (RCT). Two studies presented a high RoB, three a moderate RoB, and two a low RoB (including the RCT). A meta-analysis was not performed because of clinical, statistical, and methodological heterogeneity. Most of the studies found that pain levels in patients treated with Invisalign were lower than those treated with conventional fixed appliances during the first days of treatment. Differences disappeared thereafter. No evidence was identified for other brands of clear aligners.

CONCLUSIONS

Based on a moderate level of certainty, orthodontic patients treated with Invisalign appear to feel lower levels of pain than those treated with fixed appliances during the first few days of treatment. Thereafter (up to 3 months), differences were not noted. Malocclusion complexity level among included studies was mild. Pain is one of many considerations and predictability and technical outcome are more important, mainly considering that the difference does not seem to occur after the first months of the orthodontic treatment.

Comparison of Short-Term Oral Impacts Experienced by Patients Treated with Invisalign or Conventional Fixed Orthodontic Appliances

OBJECTIVES

Our objective was to test the hypothesis that thermoplastic clear aligners (Invisalign®; Align Technology, Santa Clara, CA, USA) are more pleasant for patients than conventional fixed orthodontic appliances.

SUBJECTS AND METHODS

This was an observational retrospective study in which subjects were matched for age, treatment modality, and the treating orthodontist. A total of 60 adult patients (30 in the Invisalign group and 30 in the conventional buccal fixed appliance group) who met the inclusion criteria completed a validated self-reporting questionnaire, rating their experience after appliance activation in regard to oral impact experience and satisfaction of both treatment modalities. Categorical variables were compared using the χ2 test, Fisher's exact test, and the Z test. Continuous variables such as pain level and age were analyzed using the 2-sample t test.

RESULTS

Patients on clear aligner therapy reported significantly more difficulty in speech (p = 0.035) necessitating change in speech delivery (p = 0.003). In addition, they reported better chewing ability (p < 0.001), no restrictions on amounts or types of food (p = 0.02), and less mucosal ulcerations (p = 0.01). Effects on daily routine, use of analgesics, and overall treatment satisfaction were not significantly different between the 2 groups.

CONCLUSION

Clear aligner therapy is not necessarily more pleasant, but it is more tolerable as it satisfies patient needs over food consumption and absence of mucosal ulcerations. However, clear aligners affect pronunciation and speech delivery in the short term.

Orthodontic Treatment with Clear Aligners and The Scientific Reality Behind Their Marketing: A Literature Review

As the demand for esthetic treatments is increasing, more people are seeking alternatives to fixed orthodontic appliances. Clear aligners are an esthetic and comfortable option for orthodontic treatment and have gained immense popularity over the last decade. This review will highlight the increasing popularity of clear aligners by describing some aligner systems frequently used today. The scope, limitations, effectiveness, efficacy, and stability of treatment results achieved with this method will be discussed. Further, this paper will assess the possible side effects caused by clear aligner treatment.

Assessment of the effectiveness of invisible aligners compared with conventional appliance in aesthetic and functional orthodontic treatment: A systematic review

To seek scientific evidence to support the effectiveness of invisible aligners, in the aesthetic and functional aspects, compared with that of conventional braces. An electronic search was performed with a complementary grey literature search for in vivo research. No language restrictions were applied. Scopus, PubMed, Web of Science, Cochrane, ClinicalTrials and GreyLiterature databases were used. Studies were first selected by title and abstract; those potentially eligible were read in full. Non-randomized studies were assessed for risk of bias using the tools Methodological Index for Non-randomized Studies (MINORS) and Cochrane Collaboration Common Scheme for Bias as a function of the presence of randomization. The search found 559 studies, of which 55 were potentially eligible. A total of 4 articles were included in this systematic literature review: three non-randomized controlled studies and one randomized controlled study, three with low risk of bias (RoB) and one with moderate RoB. Three studies showed time of correction of dental crowding shorter or equal to that of the control group and only one study showed less time of correction using conventional braces. Invisible aligners were deficient with respect to anterior/posterior and vertical corrections compared with fixed orthodontic appliances. Invisible aligners are effective in promoting dental alignment, but present clinical limitations in relation to the conventional system.

Perception of esthetic orthodontic appliances: An eye tracking and cross-sectional study

OBJECTIVE

To evaluate the perception of esthetic orthodontic appliances by means of eye-tracking measurements and survey investigation.

MATERIALS AND METHODS

En face and close-up images with different orthodontic appliances (aligner appliance [a], aligner appliance and attachments [b], lingual appliance [c], ceramic brackets [d], no appliance [e; control]) were shown to 140 participants. Eye movement and gaze direction was recorded by eye-tracking system. For different anatomical areas and areas of the appliances, time to first fixation and total fixation time were recorded. The questions included in a visual analog scale regarding individual sentiency were answered by the participants.

RESULTS

For all groups, the anatomical landmarks were inspected in the following order: (1) eyes, (2) mouth, (3) nose, (4) hair, and (5) ears. Only in group d, first fixation was on the mouth region (1.10 ± 1.05 seconds). All appliances except the lingual appliance (1.87 ± 1.31 seconds) resulted in a longer fixation on the mouth area (a, 2.97 ± 1.32 seconds; b, 3.35 ± 1.38 seconds; d, 3.29 ± 1.36 seconds). For close-up pictures, the fastest (0.58 seconds) and longest (3.14 seconds) fixation was found for group d, followed by group b (1.02 seconds/2.3 seconds), group a (2.57 seconds/0.83 seconds), and group c (3.28 seconds/0.05 seconds). Visual analog scale scoring of questions on visibility were consistent with eye-tracking measurements. With increasing visibility, the feeling of esthetic impairment was considered higher.

CONCLUSIONS

Lingual orthodontic appliances do not change how the face is perceived. Other esthetic orthodontic appliances may change the pattern of facial inspection and are different in subjective perception.

Comparison of Pain Perception in Patients Affected by Cleft and Cranio Facial Anomalies Treated With Traditional Fixed Appliances or Invisalign

Introduction:

The objective of this prospective study was to compare the difference in pain perception between treatment with aligners (AL) and fixed appliances (FA) in patients affected by cleft and craniofacial anomalies (CFA).

Methods:

The sample consisted of 100 syndromic caucasian patients affected by various CFA from 2 different hospitals. Fifty patients treated with AL were matched for sex, age, and CFA with a control sample of 50 patients treated with FA. A modification of the Mc Gill Pain Questionnaire was adapted to our needs.

Results:

Statistical differences were found. Aligners induced more tightness and tension than FA, while FA induced more pain descriptors and patients reported a higher intake of painkillers.

Conclusions:

The results of this study documented a higher pain perception with FA than with AL in patients affected by CFA. The higher sensitivity to pain in cleft and craniofacial patients with fixed treatment could be related to their higher prior sensitization, given the past surgeries and orthodontic treatments. Thus, this study might suggest that Invisalign treatment might be a further interesting treatment option for patients with cleft in order to reduce their burden of orthodontic pain.

Comparison of the Stress Strain Capacity between Different Clear Aligners

Background:

The rife use of aesthetic appliance in orthodontic treatment requires the study of the properties of the materials they are made of.

Objective:

The aim of the present study was to evaluate the dimensional stability of clear aligners made of three different materials after the application of in-vivo dynamic stress and in-vitro static stress.

Methods:

Three different aligners made of different materials (PET-G; PET; SmartTrack®), prepared on the dental arch of the same patient, were tested. For each material, three aligner samples were manufactured: one to be used in-vivo, one to be tested in-vitro, and one to be used as a control.

To evaluate the effects of the dynamic stress produced in-vivo, each aligner was worn by a single patient 22 hours per day, followed by a wash-out period of two weeks. To evaluate the effects of static stress, each aligner was exposed to the in-vitro continuous force of 50N. The tested and control aligners were scanned, then linear measurements were taken to evaluate their dimensional stability after different types of stresses.

Results:

PET seems to have the lowest percentage of deformation; PET-G and SmartTrack® showed a reduced deformation going from the posterior to the anterior area. The contact with human saliva induces a greater deformation.

Conclusion:

Different materials show different behavior following application of static stresses and dynamic stresses in the oral cavity. PET showed the highest dimensional stability.

Effects of time and clear aligner removal frequency on the force delivered by different polyethylene terephthalate glycol-modified materials determined with thin-film pressure sensors

INTRODUCTION

Many factors influence the force changes of clear aligners. The purpose of this study was to identify the various factors that influence the force changes generated by polyethylene terephthalate glycol-modified (PET-G) materials. Therefore, a force measurement system based on a flexible thin-film pressure sensor was established.

METHODS

A series of clear aligners with 2 material properties and different activations at the maxillary central incisor, maxillary second premolar, and maxillary permanent first molar was designed and fabricated. The first material was conventional PET-G; the second material was modified PET-G with a higher modulus of elasticity and greater abrasion resistance. Several models, including teeth and aligners, were produced. Then, a force change detection device, including a thin-film pressure sensor, a signal acquisition circuit board, and a computer, was applied to measure changes in the forces delivered by the conventional and modified PET-G materials with increased frequencies of appliance removal. Finally, the forces were repeatedly measured to detect the force changes over 48 hours.

RESULTS

The forces of both materials decreased similarly over time. These forces also decreased when the aligner removal frequency increased, but the forces decreased differently. The modified PET-G, with a higher modulus of elasticity and greater abrasion resistance, showed a more stable and lower force change than did the conventional PET-G.

CONCLUSIONS

The forces delivered by both materials were within the orthodontic force range. Force changes were apparent when the appliance removal frequency increased. Compared with the conventional material, the modified PET-G material showed better stability. Therefore, the modified PET-G is a promising and applicable material with advantages for both orthodontists and patients.

Pain perception among patients treated with passive self-ligating fixed appliances and Invisalign® aligners during the first week of orthodontic treatment

Objective

This study was performed to compare the perception of pain between patients treated with passive self-ligating fixed appliances and those treated with Invisalign aligners.

Methods

This prospective study conducted in Saudi Arabia used an estimated sample of 64 patients from a private dental clinic. After obtaining written informed consent, the patients were divided into two groups; one group (n = 32) was treated using passive self-ligating fixed appliances and the other group (n = 32) using Invisalign^® aligners. Immediately after fitting the appliances, the patients' perception of pain was evaluated through a close-ended and coded self-administrated questionnaire by using a visual analog scale (VAS). Their responses were recorded at 4 hours, 24 hours, day 3, and day 7. Mann-Whitney U-test, Kruskal-Wallis test, and Pearson's chi-square test were performed for statistical analysis.

Results

A lower percentage of patients treated with Invisalign aligners reported pain than did patients treated with passive self-ligating fixed appliances, and these differences were statistically significant (p = 0.001). Similarly, the mean VAS score for the Invisalign group was significantly lower than that for the passive self-ligating fixed appliance group at different intervals during the first week of treatment. The intensity of pain with both appliances peaked at 24 hours (mean VAS score, 3.87) and was lowest (mean VAS score, 1.62) on day 7.

Conclusions

During the first week of orthodontic treatment, patients treated with Invisalign aligners reported lower pain than did those treated with passive self-ligating fixed appliances.

Mechanical properties of "two generations" of teeth aligners: Change analysis during oral permanence

Aim of this in vitro study was to analyze structural properties of two different polymeric orthodontic aligners, Exceed30 (EX30) and Smart Track (LD30), before and after use. Forty patterns of aligners were randomly selected: 20 LD30 and 20 EX30, worn intra-orally for 14±3 days, 22 h/day. From each aligner, 10 specimens were prepared from buccal surfaces of the incisor region by the cutting of samples 5×5 mm under a stereomicroscope. All samples were subjected to Fourier transform infrared spectroscopy, micro-Raman spectroscopy, X-ray diffraction, tensile and indentation strength test. LD30 appeared more homogeneous, with a crystalline fraction lower than EX30 and exhibited a higher elastic behavior and a lower tendency to warp after use than EX30. LD30 demonstrated better adaptability to the dental arch and greater consistency of application of orthodontic forces than produced with EX30. However, both materials showed structural modifications that resulted in increased sample hardness and hyper-plasticity.

Patient satisfaction and quality of life changes after Invisalign treatment

INTRODUCTION

Our objective was to assess patient satisfaction and changes in oral health-related quality of life immediately after orthodontic treatment using the Invisalign system (Align Technology, Santa Clara, Calif).

METHODS

Adult patients were recruited from private practices in Canada and surveyed using a combination of 2 validated questionnaires: Dental Impact of Daily Living and Patient Satisfaction Questionnaire. This 94-question assessment focused on various dimensions of satisfaction and changes in quality of life. Multivariate analysis of variance, regression analysis, and canonical correlation analysis were applied in the data analysis.

RESULTS

A total of 81 patients, 29.6% men and 70.4% women, exclusively treated with the Invisalign system participated. The most significant improvements were seen in the appearance and eating and chewing categories, with patients responding positively to more than 70% of the questions in those categories. Food packing between teeth, affecting 24% of the participants, and pain affecting 16% were the most common sources of dissatisfaction. However, these negative experiences were not strong enough to reduce the overall positive experience that patients reported. Appearance and dentofacial improvement were strongly correlated. Canonical correlation of the Patient Satisfaction Questionnaire factors showed that doctor-patient relationship had a significant correlation with situational aspects, dentofacial improvement, and the residual category. Phrases from the doctor-patient relationship category such as "the orthodontist treated me with respect" and "carefully explained what treatment would be like" were associated with higher patient satisfaction.

CONCLUSIONS

Although positive changes in appearance and eating categories were linked with patient satisfaction, doctor-patient relationship was the factor that correlated better with multiple aspects of patient satisfaction.

Pain experience in adults undergoing treatment: A longitudinal evaluation

OBJECTIVES

To quantify the intensity and duration of pain experience in adults over the initial three visits of fixed appliance-based orthodontic treatment. A secondary objective was to assess the relationship between pain experience and analgesic use, dental irregularity, gender, and age.

MATERIALS AND METHODS

A prospective longitudinal study design was adopted. Fifty-eight adults undergoing fixed appliance treatment in five orthodontic practices recorded pain experience at four time points (4 hours, 24 hours, 3 days, and 7 days) following the initial bond-up appointment (T0) and first (T1) and second (T2) routine follow-up adjustment appointments using a visual analogue scale. In addition, subjects recorded the dosage and frequency of analgesic use.

RESULTS

A slightly greater proportion of women (57%) were recruited, with a mean sample age of 34.69 (SD 12.11) years. Peak pain was experienced between 24 hours and 3 days following appliance placement (T0) and subsequent adjustments (T1 and T2). The highest mean pain score arose at T0 followed by T2 and T1 adjustments, with the difference between pain levels at these appointment intervals being statistically significant ( P < .001). The use of analgesics following each appointment mirrored pain experience, with pain score, appointment, and time point all being significant predictors of analgesic consumption. The level of dental irregularity, gender, or age did not predict pain levels reported.

CONCLUSIONS

Adults undergoing fixed orthodontic therapy should be advised that they are most likely to experience increased levels of pain for 1 to 3 days following placement of their appliance and subsequent adjustment visits.

[Perception of pain in orthodontic treatment with thermoformed aligners]

INTRODUCTION

The aim of this study was to assess pain generated during orthodontic treatment with aligners in terms of intensity, duration and characteristics.

MATERIALS AND METHODS

The sample consisted of 106 patients. Pain was analyzed according to intensity and characteristics using the Saint Antoine Pain Questionnaire (French Mac Gill questionnaire). For statistical analysis, Student tests were performed.

RESULTS

84% of patients experienced low to moderate pain, with a significantly higher intensity in women. Thirty-one per cent of patients consumed analgesics, although no established correlation was observed between intensity of pain and analgesics. For 53% of patients, duration of pain was ≤ 2 days; for 15% of patients, the pain lasted 7 days. Among patients aged ≥ 40 years, duration of pain was significantly lower than in those aged < 40 years. Ten characteristics of pain were selected as described by at least one third of patients.

CONCLUSION

Orthodontic treatments with aligners cause mild to moderate pain, which usually lasts 2 to 3 days, but may last 7 days. This pain is described as a sensation of "compression", "twinges", "squeezing", "tightness", "stretching", "cutting", and as being "tiresome", "bothersome", "unpleasant", or even "a nuisance".

Discomfort associated with Invisalign and traditional brackets: A randomized, prospective trial

OBJECTIVE

To evaluate differences in discomfort levels between patients treated with aligners and traditional fixed orthodontic appliances.

MATERIALS AND METHODS

This blinded, prospective, randomized equivalence two-arm parallel trial allocated 41 adult Class I nonextraction patients to either traditional fixed appliance (6 males and 12 females) or aligner (11 males and 12 females) treatment. Patients completed daily discomfort diaries following their initial treatment appointment, after 1 month and after 2 months. They recorded their levels of discomfort at rest, while chewing, and while biting, as well as their analgesic consumption and sleep disturbances.

RESULTS

Both treatment modalities demonstrated similar levels of initial discomfort. There were no significant sex differences. Patients in the traditional fixed appliances group reported significantly (P < .05) greater discomfort than patients in the aligner group during the first week of active treatment. There was significantly more discomfort while chewing than when at rest. Traditional patients also reported significantly more discomfort than aligner patients after the first and second monthly adjustment appointments. Discomfort after the subsequent adjustments was consistently lower than after the initial bonding or aligner delivery appointments. A higher percentage of patients in the fixed-appliance group reported taking analgesics during the first week for dental pain, but only the difference on day 2 was statistically significant.

CONCLUSIONS

Patients treated with traditional fixed appliances reported greater discomfort and consumed more analgesics than patients treated with aligners. This trial was not registered.

Twitter analysis of the orthodontic patient experience with braces vs Invisalign

OBJECTIVE

To examine the orthodontic patient experience having braces compared with Invisalign by means of a large-scale Twitter sentiment analysis.

MATERIALS AND METHODS

A custom data collection program was created that collected tweets containing the words "braces" or "Invisalign" for a period of 5 months. A hierarchal Naïve Bayes sentiment analysis classifier was developed to sort the tweets into five categories: positive, negative, neutral, advertisement, or not applicable. Each category was then analyzed for specific content.

RESULTS

A total of 419,363 tweets applicable to orthodontics were collected. Users posted significantly more positive tweets (61%) than they did negative tweets (39%; P ≤ .0001). There was no significant difference in the distribution of positive and negative sentiment between braces and Invisalign tweets (P = .4189). Positive orthodontics-related tweets often highlighted gratitude for a great smile accompanied with selfies. Negative orthodontic tweets frequently focused on pain.

CONCLUSION

Twitter users expressed more positive than negative sentiment about orthodontic treatment with no significant difference in sentiment between braces and Invisalign tweets.

Comparison of oral health-related quality of life of patients treated by palatal expanders with patients treated by fixed orthodontic appliances

INTRODUCTION AND PURPOSE

Wearing orthodontic appliances may negatively affect a patient's oral health-related quality of life (OHRQoL) physiologically, psychologically, and socially. Few studies have assessed the effect of palatal expanders on OHRQoL. The aim of this study was to evaluate the impact of palatal expanders on OHRQoL and to compare it with that of fixed orthodontic appliances.

MATERIALS AND METHODS

All adolescent and adult orthodontic patients who were undergoing treatment with fixed appliances or palatal expanders between July 2015 and January 2016 in King Abdulaziz University Orthodontc Dental Clinics, were recruited (n=399). The OHRQoL of each participant was assessed using the shortened Arabic version of the Oral Health Impact Profile-14 questionnaire. OHRQoL was compared between users of fixed appliances and users of palatal expanders; it was also compared after stratifying the patients by gender. Chi-squared and Fisher's exact tests were used, as indicated.

RESULTS

Palatal expanders had significantly greater negative effects on chewing ability (P≤0.01) and pronunciation (P=0.048). However, fixed orthodontic appliances had significantly greater negative impacts on mouth aching (P=0.003), difficulty in relaxing (P=0.01), irritability (P=0.001), and embarrassment (P≤0.01).

CONCLUSION

Palatal expanders had a significantly greater negative impact on some aspects of OHRQoL when compared with fixed orthodontic appliances in adolescents and young adults.

Patient survey on Invisalign® treatment comparing [corrected] the SmartTrack® material to the previously used [corrected] aligner material

OBJECTIVES

In 2013, a novel material SmartTrack^® was introduced to replace the previous material used for Invisalign^® aligners. We conducted this study to test how this transition was accepted by patients during ongoing Invisalign^® treatment.

METHODS

We surveyed a total of 72 patients (68 % women, 32 % men, mean age: 29.3 ± 9.2 years) who had worn the new material for a mean of 6 months. They completed a questionnaire with 25 items that compared both materials in terms of pain, pressure upon insertion, comfort, mucosal irritation, phonetics, discoloration, and taste.

RESULTS

On a numerical rating scale (NRS) ranging from 0 to 10, the new aligner material was rated by the respondents to cause significantly (p < 0.001) less maximum pain than the old material (2.8 vs. 3.8). Significant reductions were obtained for duration of pain (p < 0.001) and duration of pressure (2.5 vs. 1.9 days; p = 0.001) upon insertion of the aligners. Over 90 % of the respondents indicated less or equal pain during eating, felt that the new material offered a tighter fit, and provided more favorable ratings for impairment, durability, and discoloration. Improved comfort was reported by 50 % of the respondents.

CONCLUSIONS

The new material was favorably rated by the patients and showed significant reductions in pain intensity, pain duration, and pressure upon insertion. Important clinical parameters like overall comfort and impairment also were improved. The clinical effectiveness of the new material remains to be investigated.

Insight into orthodontic appliance induced pain: Mechanism, duration and management

Most of the orthodontic patients experience pain during treatment and this significantly influences their attitudes and the approach towards treatment. A number of factors that influence pain response include age, gender, personal pain threshold, mood and stress level of the person, cultural differences and types of orthodontic treatment. Pain is a often overlooked subject by orthodontists, it is nevertheless important to understand the source and mechanism of the pain that occurs during treatment, as well as the methods for managing and controlling this pain. This review attempts to overview the mechanism, duration and current management strategies of orthodontic treatment.

A randomized controlled trial of self-perceived pain, discomfort, and impairment of jaw function in children undergoing orthodontic treatment with fixed or removable appliances

OBJECTIVE

To compare patients' perceptions of fixed and removable appliance therapy for correction of anterior crossbite in the mixed dentition, with special reference to perceived pain, discomfort, and impairment of jaw function.

MATERIAL AND METHODS

Sixty-two patients with anterior crossbite and functional shift were recruited consecutively and randomized for treatment with fixed appliances (brackets and archwires) or removable appliances (acrylic plates and protruding springs). A questionnaire, previously found to be valid and reliable, was used for evaluation at the following time points: before appliance insertion, on the evening of the day of insertion, every day/evening for 7 days after insertion, and at the first and second scheduled appointments (after 4 and 8 weeks, respectively).

RESULTS

Pain and discomfort intensity were higher for the first 3 days for the fixed appliance. Pain and discomfort scores overall peaked on day 2. Adverse effects on school and leisure activities were reported more frequently in the removable than in the fixed appliance group. The fixed appliance group reported more difficulty eating different kinds of hard and soft food, while the removable appliance group experienced more speech difficulties. No significant intergroup difference was found for self-estimated disturbance of appearance between the appliances.

CONCLUSIONS

The general levels of pain and discomfort were low to moderate in both groups. There were some statistically significant differences between the groups, but these were only minor and with minor clinical relevance. As both appliances were generally well accepted by the patients, either fixed or removable appliance therapy can be recommended.

Analysis of pain level in cases treated with Invisalign aligner: comparison with fixed edgewise appliance therapy

Background

The aim of this study was to evaluate and compare the difference in the level of pain using the visual analog scale (VAS) between cases treated with the edgewise appliance and Invisalign. In addition, the cause of pain and discomfort in the Invisalign cases was identified.

Methods

The sample consisted of 145 cases for the edgewise group (EG; n = 55), Invisalign group (IG; n = 38), and edgewise and Invisalign group (EIG; n = 52). VAS scores were collected during the first three stages (first stage: 0 to 7 days, second stage: 14 to 21 days, and third stage: 28 to 35 days) and at the end of the treatment (overall VAS score). Evaluation of the cause of pain was categorized into three different types of problem (category 1: non-smoothed marginal ridge or missing materials, category 2: deformation of attachments, and Category 3: deformation of the tray). Statistical comparison of VAS scores between groups was performed by two-way analysis of variance.

Results

A significantly higher VAS score was observed at 3 and 4 days after, at 1, 2, and 3 days after, and at 2 and 3 days after in stages 1, 2, and 3, respectively, in EG compared to EIG and IG. A significant difference was observed in overall VAS scores between EG and IG in intensity of pain, number of days that pain lasted, and discomfort level. Only intensity of pain resulted in a significant difference between EG and EIG. Most of the causes of problem in the Invisalign cases were deformation of the tray.

Conclusions

Invisalign may offer less pain compared to the edgewise appliance during the initial stages of treatment. In the use of Invisalign, deformation of tray must be carefully checked to avoid pain and discomfort for the patients.

Changes in the oral health-related quality of life 24 h following insertion of fixed orthodontic appliances

Objectives:

The objective of this study was to assess changes in the oral health-related quality of life (OHRQoL) among patients wearing fixed orthodontic appliances 24 h after insertion.

Materials and Methods:

Sixty patients aged between 14 and 24 years (29 males and 31 females; mean age, 17.8 years; SD 3.1 years) were recruited from the Postgraduate Clinic, Department of Children's Dentistry and Orthodontics, Faculty of Dentistry, University of Malaya. The oral health-related quality of life (OHRQoL) was measured before treatment and 24 h after insertion of the orthodontic appliance. The instrument used to measure OHRQoL was a modified self-administered short version of Malaysian Oral Health Impact Profile (OHIP-16[M]) questionnaire. The higher the score, the poorer is the OHRQoL.

Results:

Overall score of OHRQoL increased significantly 24 h after insertion (mean 43.5±10.9) as compared to before insertion (mean 34.1±9.2) (P<0.001). Significant changes were found for the following items: Difficulties in chewing, bad breath, difficulties in pronunciation, discomfort in eating, ulcer, pain, avoidances of eating certain foods, difficulties in cleaning, embarrassment, avoid smiling, disturbed sleep, concentration affected, difficulty carrying out daily activities, and lack of self-confidence (P<0.05). Significant changes were also found in the mean difference of OHRQoL for gender (P<0.001).

Conclusion:

OHRQoL was found to deteriorate 24 h after insertion of fixed orthodontic appliances in almost all domains, with significant changes in gender. This information can be used as “informed consent”, which might increase patient's compliance as they are aware of what to expect from initial orthodontic treatment.

Changes of substance P in the crevicular fluid in relation to orthodontic movement preliminary investigation

Substance P (SP) is a tachykinin released from both the central and the peripheral endings of primary afferent neurons and functions as a neurotransmitter. As a transmitter signaling pain, substance P is involved in nociception and is an extremely potent vasodilator. We found several studies about this neuropeptide especially in relation to parodontology and a few orthodontic reviews. This is because in the past the importance of this neuropeptide in dental element undergoing periodontal inflammation was observed. The aims of the present pilot study was to investigate whether the substance P was present in gingival crevicular fluid in dental elements undergoing orthodontic treatment with Invisalign technique compared to teeth belonging to the same series but not undergoing orthodontic movement. We analysed gengival crevicular fluid (GCF) collected from four young subjects, using a paper cone for a time of 60 seconds. The results showed that SP is present in the gengival sulcus in elements undergoing orthodontic forces during treatment with Invisalign technique and not in the control teeth. During the literature analysis, we have found a lot of papers describing involvement of SP in periodontitis and inflammatory diseases, but further studies are needed in order to demonstrate the role of this neuropeptide during teeth movement.

The impact of personality on adult patients' adjustability to orthodontic appliances

OBJECTIVE

To evaluate the impact of psychological traits on patients' choice of orthodontic appliances and their adjustability to orthodontic treatment.

MATERIALS AND METHODS

The sample consisted of 68 adult patients divided into three groups (28 buccal, 19 lingual, and 21 clear aligners). Prior to treatment participants filled out the Brief Symptom Inventory to assess symptoms of mental distress and the Narcissistic Vulnerability Scale to assess narcissistic personality traits. During the first week after appliance delivery and on day 14, patients completed a Health-Related Quality of Life questionnaire to assess their perception of pain and four areas of dysfunction. The correlation between personality traits and patients' reaction to treatment was evaluated.

RESULTS

Somatization was the only trait that affected the choice of lingual and clear aligner appliance. Reduced self-esteem regulation was associated with increased pain in all patients, while exploitation was associated with pain in lingual patients. Narcissistic vulnerability slightly influenced patients' adaptability to orthodontic appliances. Although adjustability to lingual appliances was the most difficult, only two parameters were affected by personality features. In the buccal group, adjustability was affected by numerous parameters. Adaptation to the clear aligner appliance was relatively uneventful and least affected by psychological features.

CONCLUSION

Anxious individuals tend to prefer lingual and clear aligner appliances. The selection of lingual and clear aligner appliances governs the patient's response and recovery process, leaving little room for the effect of psychological features. On the other hand, the buccal appliance allows for greater impact of personality traits on adjustability.

Invisalign, an innovative invisible orthodontic appliance to correct malocclusions: advantages and limitations

Tooth movement may be achieved by the use of sequential positioners made by altering tooth positions on set-up models to simulate progress of treatment. The principle is based upon Kesling's positioner concept of 1945, though its subsequent application to splint therapy was labour intensive and did not result in precise tooth movement. Invisalign was developed by Align Technology, Inc (Santa Clara, CA, USA) in 1997 by applying 3-D imaging technology to overcome these problems, and permitting customization on a large scale. Their system offers significant advantages, but still suffers from limitations which are discussed in this article.

The effect of chewing gum on the impact, pain and breakages associated with fixed orthodontic appliances: a randomized clinical trial

OBJECTIVES

To determine whether the use of chewing gum reduced the impact and pain of fixed orthodontic appliances.

SETTING AND SAMPLE POPULATION

The Orthodontic Department of the Charles Clifford Dental Hospital, Sheffield, UK. Fifty-seven patients aged 18 years or younger and who were about to start fixed orthodontic appliance treatment.

SUBJECTS AND METHODS

A randomized clinical trial with two parallel groups either allocated to receive chewing gum after placement of their appliance or who were asked not to chew gum. The patients completed a previously validated Impact of Fixed Appliances questionnaire at 24 h and 1 week following each visit up until the placement of the working archwire. A visual analogue scale (VAS) was used to assess the intensity of pain. Appliance breakages were recorded to the end of treatment.

RESULTS

The difference between the median Total Impact Score of the two groups at 24 h was 16, which was significant (p = 0.031; Mann-Whitney U-test). The difference between the median VAS between the two groups at 24 h was 25 mm, which was significant (p = 0.038; Mann-Whitney U-test). There were no differences at 1 week. None of the risk ratios for appliance breakages were significant.

CONCLUSION

Chewing gum significantly decreased both the impact and pain from the fixed appliances. There was no evidence that chewing gum increased the incidence of appliance breakages.

Preparation and characterization of thermoplastic materials for invisible orthodontics

PETG/PC/TPU polymer blend was prepared by mechanical blending. The mechanical properties of modified PETG/PC/TPU blend were characterized using a universal testing machine, and results were compared against two commercial thermoplastic products -Erkodur and Biolon. Blending modification improved the properties of PETG/PC/TPU. When blending ratio (wt%) was 70/10/20, PETG/PC/TPU exhibited optimal mechanical properties which exceeded those of Erkodur and Biolon. Tear strength was 50.23 MPa and elongation at break was 155.99%. Stress relaxation rate was 0.0136 N/s after 1 hour, which was significantly slower than Erkodur and Biolon (p<0.05). Water absorption rate was 0.57% after 2 weeks, which was significantly lower than Erkodur and Biolon (p<0.05).