Prevalence of temporomandibular disorders in clear aligner patients using orthodontic intermaxillary elastics assessed with diagnostic criteria for temporomandibular disorders (DC/TMD) axis II evaluation: A cross-sectional study

BACKGROUND

The objective of this investigation is to assess the relationship between the utilisation of orthodontic intermaxillary elastics and temporomandibular disorder (TMD) symptoms in clear aligner patients and to examine the correlation between the elastic usage time with the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD)-Axis II Evaluation Forms.

METHODS

This study was carried out on a total of 40 clear aligner patients using intermaxillary elastics in the experimental group and 30 clear aligner patients who did not use any intermaxillary elastics in the control group. The data were evaluated using the Mann-Whitney U, chi-square, Fisher's exact chi-square, and Fisher Freeman Halton exact chi-square tests.

RESULTS

The characteristic pain intensity, mastication, mobility, communication, global and PHQ-9 scores of the experimental group were significantly higher than those of the control group (p < .05). The characteristic pain intensity score, interference score and chronic pain grade score of patients using Class III elastics were statistically significantly higher than those of patients using Class II elastics (p < .05). Patients who used elastics for less than 6 months had statistically significantly higher PHQ-9 scores than those who used elastics for more than 6 months (p < .05).

CONCLUSIONS

Orthodontic treatment may affect occlusion, bite force and jaw movement, which may cause or worsen TMD symptoms, and the DC/TMD questionnaires can determine if orthodontic patients acquire TMD by assessing their psychosocial state and pain-related problems.

Comparison of sleep quality between clear aligner and fixed appliance orthodontic therapies

BACKGROUND

Although available evidence suggests that orthodontic appliances can impact quality of life, there is limited information on the impact of orthodontic appliances on sleep quality. This study aimed to compare sleep quality between patients undergoing orthodontic treatments using conventional fixed appliances and clear aligners.

METHODS

Adult patients attending clinics in Saudi Arabia participated in this cross-sectional study. Sleep quality was assessed using the validated Arabic version of the Pittsburgh Sleep Quality Index (PSQI) and the Epworth Sleepiness Scale (ESS). Statistical significance was determined using inferential analysis, with a P < 0.05 considered statistically significant.

RESULTS

There were 69 patients included in the study. The average age of a patient (33.12 ± 8.1) who received the clear aligner was significantly higher than those who received the fixed appliance (27.7 ± 5.9) (P < 0.05). The variation in the average score of ESS because of the education level was found to be statistically significant (P < 0.05). No significant difference was observed between the mean average ESS and PSQI global scores across the two orthodontic treatment groups. The average sleep latency scores were significantly higher in females than males when analyzing the PSQI component score across sex (P < 0.05). In education, ESS, PSQI global, habitual sleep efficiency, the use of sleep medication, and daytime dysfunction had a positive, weak, but significant correlation.

CONCLUSIONS

Overall, this study concluded that regardless of the orthodontic appliances used, there was no statistically significant difference in sleep quality during the treatment.

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 periodontal status of removable appliances vs fixed appliances: A comparative meta-analysis

BACKGROUND

Although several researchers have analyzed the dental identity of patients experience with corrective methods using fixed and removable appliances, the consequences stay debatable. This meta-analysis intended to verify whether the periodontal status of removable appliances is similar to that of the conventional fixed appliances.

METHODS

Relevant literature was retrieved from the database of Cochrane library, PubMed, EMBASE, and CNKI until December 2019, without time or language restrictions. Comparative clinical studies assessing periodontal conditions between removable appliances and fixed appliances were included for analysis. The data was analyzed using the Stata 12.0 software.

RESULTS

A total of 13 articles involving 598 subjects were selected for this meta-analysis. We found that the plaque index (PLI) identity of the removable appliances group was significantly lower compared to the fixed appliances group at 3 months (OR = -0.57, 95% CI: -0.98 to -0.16, P = .006) and 6 months (OR = -1.10, 95% CI: -1.60 to -0.61, P = .000). The gingival index (GI) of the removable appliances group was lower at 6 months (OR = -1.14, 95% CI: -1.95 to -0.34, P = .005), but the difference was not statistically significant at 3 months (OR = -0.20, 95% CI: -0.50 to 0.10, P = .185) when compared with that of the fixed appliances group. The sulcus probing depth (SPD) of the removable appliances group was lower compared to the fixed appliances group at 3 months (OR = -0.26, 95% CI: -0.52 to -0.01, P = .047) and 6 months (OR = -0.42, 95% CI: -0.83 to -0.01, P = .045). The shape of the funnel plot was symmetrical, indicating no obvious publication bias in the Begg test (P = .174); the Egger test also indicated no obvious publication bias (P = .1).

CONCLUSION

Our meta-analysis demonstrated that malocclusion patients treated with the removable appliances demonstrated a better periodontal status as compared with those treated with fixed orthodontic appliances. However, the analyses of more numbers of clinical trials are warranted to confirm this conclusion.

Expansion treatment using Invisalign®: Periodontal health status and maxillary buccal bone changes. A clinical and tomographic evaluation

The aim of this study was to evaluate changes in periodontal status and maxillary buccal bone by considering clinical and tomographic parameters during the first year of orthodontic expansion with Invisalign® aligners. Upper first (1PM) and upper second (2PM) premolars of 19 patients with orthodontic expansion requirement treated with Invisalign® aligners were evaluated. Plaque index (PI), gingival index (GI), probing pocket depth (PPD), clinical attachment level (CAL) and cone beam tomographic (CBCT) records were collected at 76 sites before starting treatment (T0) and at 12 months (T1). Bone height was measured from cementoenamel junction (CEJ) to the crest cortical bone (CC). Bone thickness was measured at two levels: 4 mm (CEJ+4) and 6 mm (CEJ+6) apical to the CEJ. A descriptive analysis was made of the variations of bone thickness and height in a series of cases. The average expansion was 1.93 mm for 1PM and 167 mm for 2PM. Arithmetic mean of distance CEJ-CC in 1PM was 3.05 mm at T0, and remained at 3.05 mm at T1. Arithmetic mean of distance CEJ-CC in 2PM was 2.06 mm at T0 and 2.31 at T1. Post-expansion, most of the analyzed sites (86%) exhibited a bone thickness of ≥0.5 mm. The greatest variations between T0 and T1 were observed at the level of 1PM CEJ+ 4 and 2PM CEJ+ 6. The minimal changes in the clinical records (GI, PI, PPD and CAL) between T0 and T1 were compatible with the maintenance of gingivalperiodontal health. Invisalign® for expansion movements did not produce substantial changes in the evaluated periodontal clinical parameters or in the bone measurements. Removable appliances reduce plaque retentive factors and favor adequate oral hygiene.

Salivary concentrations of Streptococcus mutans and Lactobacilli during an orthodontic treatment. An observational study comparing fixed and removable orthodontic appliances

AIM

This study aimed to investigate salivary concentrations of Streptococcus mutans (S. mutans) and some Lactobacilli, and plaque index (PI) in patients wearing fixed versus removable orthodontic appliances.

METHODS

A sample of 90 orthodontic patients (56 males and 34 females) was included in the study: 30 subjects (aged 21.5±1.5 years) were treated with removable clear aligners (CA), while for other 30 cases (aged 23.3±1.6 years) a fixed multibrackets appliance (MB) were utilized, and 30 patients (aged 18.2 ±1.5 years) wearied a removable positioner (RP). Salivary concentrations of S. mutans and Lactobacilli and PI were evaluated prior to start of the orthodontic treatment, after 3 months and 6 months.

RESULTS

After 6 months, 40% of MB patients (12 subjects over 30) showed a concentration of S. mutans associated to high risk of developing tooth decay (CFU/ml>105 ), differently from participants wearing removable appliances (odds ratio = 5.05; 95% C.I. = 1.72-14.78; chi-square = 9.64; p = 0.0019). The same trens was observed for the concentration of Lactobacilli (odds ratio = 4.33; 95% C.I. = 1.53-12.3; chi-square = 8.229; p = 0.004). In addition, over the duration of the study, CA patients maintained PI at 0 level, while MB patients experienced a statistically significant increasing trend of PI over time, and their PI became clinically/statistically relevant after 6 months, respect to CA and RP patients.

CONCLUSIONS

Comparing all the data, while, after 6 months, only about 10% of CA patients and 13.3% of RP patients achieved a microbial colonization which may lead to high risk of caries development, about 40% of MB patients - and 20% after 3 months - showed a high level of vulnerability to developing caries, which require additional strategies for plaque control and microbial colonization to be employed.

Comparative evaluation of salivary microbial levels and periodontal status of patients wearing fixed and removable orthodontic retainers

INTRODUCTION

The purpose of this study was to compare and evaluate salivary microbial levels and periodontal status in patients using a fixed lingual retainer, a removable vacuum-formed retainer, or a Hawley retainer after orthodontic treatment with fixed appliances.

METHODS

Forty-five patients who finished their orthodontic treatment with fixed appliances and were about to start the retention phase were randomly divided into the following 3 groups of 15 individuals each: the fixed lingual retainer group, the vacuum-formed retainer group, and the Hawley retainer group. Periodontal measurements, such as the plaque index, gingival index, probing depth, and bleeding on probing, were obtained at the following 4 time points: at debonding (T0) and 1 week (T1), 5 weeks (T2), and 13 weeks (T3) after debonding. Saliva samples were collected 3 times in total: at T0, T2, and T3. A quantitative analysis for Streptococcus mutans and Lactobacillus casei was performed with the use of real-time polymerase chain reaction. The Kruskal-Wallis test and 1-way analysis of variance were used for the statistical comparisons of the groups.

RESULTS

No statistically significant difference in salivary S mutans and L casei levels was found among the 3 groups (P >0.05). They showed no statistically significant differences in plaque index, gingival index, bleeding on probing, and probing depth values (P >0.05). All periodontal parameters showed statistically significant decreases from T0 to T3 in all 3 groups (P <0.001). The S mutans and L casei levels were decreased significantly from T2 to T3 in the lingual retainer and Hawley retainer groups, whereas they decreased significantly from T0 to T3 in the vacuum-formed retainer group.

CONCLUSIONS

Fixed and removable orthodontic retainers do not differ in salivary S mutans and L casei levels and periodontal status. With all retainers, regardless of whether they are fixed or removable, oral hygiene improved after orthodontic treatment with fixed appliances.

Effects of Invisalign® treatment on speech articulation

OBJECTIVES

To determine the effects of Invisalign^® aligners on patients' abilities to articulate consonants.

MATERIALS AND METHODS

Thirty patients undergoing active two-arch Invisalign^® treatment were examined. Patients were recorded reading the rainbow passage (a passage with every phoneme represented), once with the trays inserted and once with the trays removed. The recordings were analysed by a speech pathologist for misarticulation of consonant phonemes.

RESULTS

Misarticulation of consonants was significantly associated with the Invisalign^® aligners inserted as based on the McNemar's statistical test (P=0.008). The fricative alveolar consonant /z/ was found to be the most impacted by the trays, followed by the consonant /s/ (P=0.016). The consonant /sh/ was not shown to be affected by the Invisalign^® aligners.

CONCLUSIONS

Invisalign^® aligners do have an impact on the articulation of consonants. Fricative alveolar consonants were the primary phonemes impacted. Due to the fact that the efficacy of Invisalign^® treatment is based primarily on compliance and that speech impairment may interfere with compliance, the information presented in this study should be conveyed to the patient before the initiation of Invisalign^® treatment.

In vitro cytotoxicity of different thermoplastic materials for clear aligners

OBJECTIVES

To investigate the in vitro cytotoxicity of different thermoplastic materials for clear aligners on human primary gingival fibroblasts (HGFs).

MATERIALS AND METHODS

Four materials for clear aligners were considered in this study: Duran (Scheu-Dental GmbH, Iserlohn, Germany), Biolon (Dreve Dentamid GmbH, Unna, Germany), Zendura (Bay Materials LLC, Fremont, CA, USA), and SmartTrack (Align Technology, San Jose, CA, USA). Three out of four materials (Duran, Biolon, Zendura) were assessed as thermoformed and nonthermoformed, whereas the SmartTrack was assessed only as thermoformed. The samples were placed at 37°C in airtight test tubes containing Dulbecco's Modified Eagle's Medium (DMEM; 0.1 mg/mL) for 14 days. The cell viability of HGFs cultured with this medium was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Data were analyzed by means of one-way and two-way analysis of variance and post hoc tests (α = 0.05).

RESULTS

Each material exhibited a slight cytotoxic effect after 14 days. The highest cytotoxicity level on HGFs was achieved by Biolon (64.6% ± 3.3 of cell viability), followed by Zendura (74.4% ± 2.3 of cell viability), SmartTrack (78.8% ± 6.3 of cell viability), and finally Duran (84.6% ± 4 of cell viability), which was the least cytotoxic. In the comparison between nonthermoformed and thermoformed materials for Duran, Biolon, and Zendura, the thermoformed materials showed the highest level of cytotoxicity (P < .001).

CONCLUSIONS

Under the experimental conditions of this study, all the materials for clear aligners presented a slight cytotoxicity. Biolon was the most cytotoxic and the thermoforming process increased the cytotoxicity of the materials.

Association of Orthodontic Clear Aligners with Root Resorption Using Three-dimension Measurements: A Systematic Review

AIM

This paper aims to assess the evidence in the literature reporting orthodontically induced inflammatory root resorption (OIIRR) in treatment with orthodontic clear aligners using 3D measurements.

MATERIALS AND METHODS

Following preferred reporting Items for systematic reviews (PRISMA) statement, eight electronic databases were searched for relevant published and unpublished records. Data collected according to restricted inclusion and exclusion criteria.

RESULTS

A total of 236 articles were identified as relevant to our topic. Duplicates were excluded resulting in 226 papers, out of which 31 papers were relevant after screening titles and abstracts. Only 2 high-level evidence papers out of the 31 met the inclusion criteria for the qualitative synthesis.

CONCLUSION

Based on the available studies with high level of evidence in the literature, we conclude that orthodontic clear aligners are non-inferior to light-force fixed orthodontic appliances, and superior to heavy-force fixed orthodontic appliances in terms of the risk for developing apical root resorption.

CLINICAL SIGNIFICANCE

Orthodontists can be more assured about the low-risk of OIIRR associated with clear aligners compared to other orthodontic treatment modalities, and it remains up to the practitioner's assessment to select the appropriate treatment on a case by case basis.

In Vitro Assessment of Cytotoxicity and Estrogenicity of Vivera® Retainers

AIM

To investigate the cytotoxicity and estrogenicity of Vivera® retainers by assessing their biological behavioral effects as-received from the manufacturer and after retrieved from patients.

MATERIALS AND METHODS

In this, in vitro investigation six sets (maxillary and mandibular) of Vivera® retainers, three as received and three retrieved after four weeks of use by patients of an orthodontic postgraduate clinic, were immersed in the normal saline solution for 14 days following different modes of sterilization. The estrogenicity assays involved two cell lines, namely the estrogen-sensitive MCF-7 and the estrogen-insensitive MDA-MB-231. Following a 6 day incubation with the solutions to be tested, at concentrations varying from 5% to 20% v/v in medium supplemented with 2% fetal calf serum devoid of endogenous estrogens, estrogenicity was assessed by cell counting; p-Estradiol was used as positive control. The statistical analysis of data was performed with two-way analysis of variance (ANOVA) with appliance and concentration as predictors. Differences were further investigated with the Tukey multiple comparison tests at the 0.05 level of significance.

RESULTS

No significant MCF-7 proliferation was induced by the three samples compared either to the eluents from as-received retainers or to the negative control. As expected, p-estradiol induced a potent stimulation of MCF-7 cell proliferation, while no effect was observed on MDA-MB-231 cells.

CONCLUSION

Under the conditions of this experiment eluents of as-received and retrieved Vivera® retainers did not seem to exhibit xenoestrogenic activity.

CLINICAL SIGNIFICANCE

Vivera® retainers can be used as part-time removable oral appliances following the manufacturer's instructions.

Salivary levels of cariogenic bacterial species during orthodontic treatment with thermoplastic aligners or fixed appliances: a prospective cohort study

BACKGROUND

Fixed orthodontic appliances might be associated with intraoral adverse effects on enamel, due to plaque accumulation and their colonization by oral microbes. At the same time, the demand for esthetic alternatives to orthodontic treatment, like thermoplastic aligners, is growing. However, thermoplastic aligners may behave differently intraorally than fixed appliances in terms of bacterial colonization and biofilm formation. Therefore, the aim of this prospective cohort study was to assess the salivary prevalence of the cariogenic bacteria Streptococcus mutans, Lactobacillus acidophilus, and Streptococcus sanguinis among adolescents treated orthodontically with thermoplastic aligners or fixed appliances.

METHODS

Thirty adolescent patients (17 girls/13 boys; mean age 13.8 years old) were assigned to treatment with either (i) self-ligating fixed appliances with nickel-titanium archwires or (ii) aligners constructed from clear transparent polyethylenterephthalat-glycol copolyester (PET-G) thermoplastic sheets. Whole stimulated saliva was collected from each patient at three time points: at baseline (before bonding and initiation of orthodontic therapy or before insertion of the thermoplastic aligners), after 2 weeks, and after 1 month. A simplified plaque index, a simplified gingival index, and the decayed, missing, and filled teeth (DMFT) index were assessed from the clinical examination of the patients. Microbiological analysis of salivary bacteria was performed by quantitative polymerase chain reaction, followed by descriptive and inferential statistics at the 5% level.

RESULTS

Although patients treated with aligners had significantly lower plaque and gingivitis scores throughout treatment compared to patients treated with fixed appliances, no significant difference could be found between the S. mutans counts of the two groups at any time through treatment (P > 0.05). On the other hand, patients treated with aligners had significantly lower salivary S. sanguinis counts at all time points than patients treated with fixed appliances (P < 0.05). Finally, almost no L. acidophilus were identified in the collected saliva samples in either of the treated samples.

CONCLUSIONS

Within the limitations of this study, there were no differences in the salivary counts of S. mutans or L. acidophilus among adolescent patients treated for 1 month with thermoplastic aligners or self-ligating appliances. On the other hand, patients treated with aligners had lower salivary levels of S. sanguinis compared to those treated with self-ligating appliances.

[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".

MICROBIOLOGICAL ASPECTS OF THE ORTHODONTIC TREATMENT

An orthodontic appliance in the mouth worsens conditions for its self-cleaning, complicates the teeth care and makes an environment favorable to the soft tooth deposit, in turn, leads to the teeth enamel demineralization. In literature, the majority of works are devoted to the study of the microbial landscape with fixed orthodontic treatment. Despite the obvious relevance, the formation problem of opportunistic and pathogenic microorganisms when treating dentoalveolar anomalies with a removable orthodontic appliance remains understudied. The research aim was to investigate the influence of the removable type of orthodontic treatment of patients aged 12 with dentoalveolar anomalies on the mouth microbiocenosis. The dental examination and microbiological study was conducted to 100 children aged 12 with dentoalveolar anomalies. The dental examination included assessment of the oral hygiene state by the OHI-S index. The microbiological research was conducted in the following sequence: the bacterioscopy smear of plaque, stained by the Gram and Burri method with the assessment of morphological and tinctorial properties of microorganisms. The statistical data analysis was performed using SPSS v22.0 forWindows program. The dental examination showed that the oral hygiene state varied according to the orthodontic treatment stage. During the orthodontic treatment the OHI-S Index was 2.1 score, indicating a satisfactory oral hygiene level. The microbiological study showed that persistent contaminants were lactobacilli, streptococci, staphylococci, and yeast-like fungi. However, the treatment showed a decrease of normal flora level and the increase in number of Candidaalbicans, Staphylococcusaureus and Streptococcusmutans, that was a trigger in the development of dental caries and periodontal disease. During the orthodontic treatment, children with dentoalveolar anomalies are at high risk of dental caries and periodontal disease.

[Ultrastructural changes of human dental hard tissues during orthodontic treatment with fixed appliances]

The aim of the study was to evaluate ultrastructural changes of dental enamel after fixation of orthodontic appliances, initial influence of orthodontic forces and removal of braces. Five intact permanent tooth extracted for orthodontic reasons were included in the experimental study. Scanning probe microscopy was conducted in 4 random enamel points in each tooth (20 points overall) in semi-contact mode with standard 10 nm probes. The study showed ultrastructural enamel changes such as nanofractures up to 1 mm along the braces locks. The changes correlated with surface morphological features and teeth anatomy and may play an important role in dental decay and non-carious lesions occurring in the course of orthodontic treatment.

Possible association between mandibular repositioning device for sleep apnea and osseous lytic lesion with fracture of the coronoid process of the mandible: A case report

Mandibular repositioning devices (MRDs) increase the patency of the upper airway by repositioning the mandible forward, resulting in displacement of the oropharyngeal tissues preventing upper airway collapsibility. Mandibular anterior repositioning is counteracted by muscle force from the temporalis muscle. A 39-year-old man had an osteolytic lesion with fracture of the coronoid process of the mandible secondary to wearing a MRD for sleep apnea. Continuous stress generated on the coronoid process temporalis muscle resulted in osteolysis and fracture of the coronoid process on the patient's right side, resulting in swelling and limited ability to open his mouth. The patient was managed with intravenous antibiotics to control the osteomyelitis and surgical debridement, with removal of the coronoid process of the mandible. It is unclear why the fracture only occurred on the right side. Pathologic fracture of the coronoid process due to chronic stress and secondary osteomyelitis is a rare severe complication of treatment for obstructive sleep apnea syndrome with a MRD.

[Dental changes of patients with obstructive sleep apnea and hypopnea syndrome treated by oral appliance for more than 6 years]

OBJECTIVE

To investigate dental changes in long-term oral appliance treatment of obstructive sleep apnea and hypopnea syndrome(OSAHS).

METHODS

A total of 7 patients were included in the study. The three-dimensional (3D) model study was used to investigate the delicate changes of dentition.

RESULTS

The 7 patients who had been treated with an oral appliance for a mean duration of 8.5 years were recruited. The arch widths increased in the molar area. The distance between the distobuccal cusps of the left and right upper second molar increased (2.11 ± 2.14) mm, P=0.040. The distance between the distobuccal cusps of the left and right upper first molar increased (0.56 ± 0.61) mm, P=0.049. The distance between the distobuccal cusps of the left and right lower first molar increased (1.25 ± 0.93) mm, P=0.040. Several molar and premolar cusps were depressed. Other teeth had no change statistically.

CONCLUSION

The orthodontic side-effects on the teeth are small during the treatment of patients with OSAHS.

Emergency orthodontic care

Orthodontic appliances or parts of orthodontic appliances have caused problems from less severe like discomfort, ulcers and irritation of lips or cheeks to most severe problems like swallowing or aspiration of appliances or its parts. The type of appliances that have caused problems and their clinical management are discussed. Suggestions are made to try and avoid the problems that were encountered in the literature in patients undergoing orthodontic treatment.

Clinical and microbiological studies of children and adolescents receiving orthodontic treatment

PURPOSE

This case-controlled study examined clinical and microbiological parameters in Brazilian children and adolescents receiving orthodontic treatment using fixed orthodontic appliances or removable orthodontic appliances.

METHODS

The plaque index, gingival index, number of decayed, missing and filled teeth, and probing pocket depth was measured on each fully erupted tooth in 30 patients treated with fixed orthodontic appliances and an equal number of age and sex-matched control subjects. The same parameters were also measured in 18 patients treated with removable orthodontic appliances and an equal number of age and sex-matched control subjects. In the patients treated with fixed orthodontic appliances, subgingival plaque samples were collected from four teeth with orthodontic brackets and from four teeth with orthodontic bands. In the patients with removable appliances, subgingival plaque samples were collected from clasped maxillary permanent first molar teeth and from four unclasped permanent teeth. Samples of unstimulated whole saliva and samples from the dorsal surface of the tongue were also obtained from each subject. Each sample was analyzed for the presence of 19 target bacteria by dot blot. A subset of samples was examined by direct amplification of bacterial nucleic acids.

RESULTS

Compared to their respective age and sex-matched controls, whole mouth means for plaque index and gingival index were significantly elevated in both the fixed and removable orthodontic groups. There was no difference in the DMFT. Subjects with fixed orthodontic appliances had a higher prevalence of each of the target species except for L. fermentum, Neisseriaceae and S. mutans. The prevalence of A. naeslundii and Streptococcus sp. was significantly higher on teeth with orthodontic brackets alone compared to teeth with both orthodontic bands and brackets. Subjects with removable orthodontic appliances had a higher prevalence of A. actinomycetemcomitans, C. rectus, E. corrodens, L. fermentum, Neisseriaceae, and spirochetes. The prevalence of Neisseriaceae was significantly higher on unclasped teeth compared to clasped teeth. There was no difference between sample sites for the target bacteria except for A. actinomycetemcomitans that was detected less frequently in saliva. Orthodontic patients demonstrated higher proportions of gram negative species by direct amplification of nucleic acids including species frequently associated with periodontal disease as well as rarely cultivable or non-cultivable species such as Abiotrophia defectiva, Gemella haemolysans, Granulicatella adiacens, Lautropia sp., Terrahaemophilus aromaticivorans, and TM7 bacterium.

Halitosis, oral health and quality of life during treatment with Invisalign(®) and the effect of a low-dose chlorhexidine solution

AIM

This study examined how halitosis, oral dryness and general oral health were impacted during treatment with the Invisalign(®) system. Furthermore, the effect of a lowdose chlorhexidine solution (CHX) was evaluated.

PATIENTS AND METHODS

Thirtyone patients with good periodontal health participated in this crossover study and were divided into two groups (group 1: CHX/no CHX, group 2: no CHX/CHX). The following parameters were recorded during the first 8 months of Invisalign(®) treatment: stimulated saliva flow rate, organoleptic index, tongue coating index, measurement of the oral volatile sulfur compound level (ppb), modified gingival and plaque index and bleeding on probing index. Professional oral cleaning was performed at the beginning of each period lasting 3 months. The patients received a questionnaire at the first, third, fourth, sixth and eighth control visits.

RESULTS

The very low volatile sulfur compound level was significantly decreased by CHX (0.06%) during the first examination period (p = 0.02), i.e. for the first group of patients only. Neither halitosis, nor oral dryness, nor high plaque or gingival index measurements were observed. Oral health-related quality of life was hardly influenced by wearing aligners and oral hygiene habits were very good.

CONCLUSIONS

This study provides evidence that Invisalign(®) treatment is characterized by only minimal impairment of overall oral health and the associated quality of life. Consequently, it appears unnecessary to recommend the general adjunctive use of a low-dose chlorhexidine mouthwash during treatment with Invisalign(®).

The tongue-retaining device: efficacy and side effects in obstructive sleep apnea syndrome

STUDY OBJECTIVES

The tongue-retaining device is a customized monobloc oral appliance used in the treatment of obstructive sleep apnea syndrome (OSAS). This study evaluated tongue-retaining device efficacy and its tolerance by patients with OSAS.

METHODS

The charts of 84 apneic patients were retrospectively analyzed, and patients were contacted by telephone to answer an oral questionnaire. The median follow-up time was 5 years.

RESULTS

Based on the apnea-hypopnea index, a complete or partial response was obtained in 71% of the cases. The mean apnea-hypopnea index decreased significantly from 38 to 14 (p < 0.001) with the tongue-retaining device. The subjective intensity of snoring decreased by 68% (p < 0.0001) and the Epworth Sleepiness Scale score decreased from 9 to 6 (p < 0.05). An age of more than 60 years associated with a mandibular protrusion distance inferior or equal to 7 mm was predictive of a nonresponse (odds ratio [OR]: 7.25; 95% confidence interval [CI]: 1.43-36.7; p < 0.02). The compliance rate, as determined by answers to the questionnaire, was 52% after 5 years of follow-up. Nasal obstruction was a negative predictor of good compliance (OR: 6.94; 95% CI: 0.28-0.79; p < 0.005), whereas patients with Class I occlusion were more compliant than patients with Class II or III occlusions (OR: 3.83; 95% CI: 1.00-2.81; p < 0.05).

CONCLUSIONS

Tongue-retaining device performance tended to be similar to that of the mandibular advancement device. Thus, teams trained in tongue-retaining device fabrication and fitting may propose it as an alternative to continuous positive airway pressure, taking nasal obstruction into consideration as a contraindication.

A comparison of the periodontal health of patients during treatment with the Invisalign system and with fixed orthodontic appliances

OBJECTIVE

Evaluation of the periodontal health in patients during treatment with either fixed orthodontic appliances or the Invisalign system.

STUDY DESIGN

The study was designed as a concomitant trial. The evaluation of the patients started in February 2002 and was completed in August 2003.

PATIENTS AND METHODS

Thirty consecutive patients each with fixed orthodontic appliances and with aligners were examined at three consecutive control visits for their periodontal condition. All individuals were part of the clientele of the Department of Orthodontics and Dentofacial Orthopedics of the Charité Berlin. The parameters evaluated were the modified Gingival Index, modified Plaque Index, modified Papillary Bleeding Index, and sulcus probing depth. The first three indices were recorded alternatively buccally and lingually in all permanent teeth from central incisor to first molar: buccally in the maxillary right and the mandibular left quadrants, lingually in the maxillary left and mandibular right quadrants. The sulcus depth was measured in four areas: mesially and distally, lingually and buccally in the 1st molar and the 1st premolar of each quadrant. Each control visit was concluded with a detailed, individualized oral hygiene instruction.

RESULTS

The modified Plaque Index was significantly lower in the Invisalign group overall. On the other hand, the periodontal condition of the two samples was nearly identical.

CONCLUSION

Periodontal health is not jeopardized, even though the Invisalign system aligners cover all the teeth and the keratinized gingiva in part. This could be attributed to the fact that aligners are removable and thus allow unimpeded oral hygiene.

[Influence of oral appliances for obstructive sleep apnea syndrome on stomatognathic system part 1. Occlusion]

PURPOSE

Little information is available on the mandibular protrusion with oral appliances (OA) for the treatment of obstructive sleep apnea syndrome (OSAS) to have no negative effect on the stomatognathic system. The purpose of the current study was to assess the influence of mandibular protrusion on occlusion to fabricate the appropriate OA.

METHODS

Twelve healthy adults were selected. With the OA in position, the mandible was advanced 0, 45, 60, 75% of maximum protrusion capacity; bite raising distance between the first molars was 5mm (OA5-0, 45, 60 and 75). The occlusal force, occlusal contact area and occlusal load center following maximum voluntary clenching for 5 seconds were investigated as follows: after wearing the OA for 1, 3 and 6 hours (Stage A1, A3 and A6) and 1 hour after removal (Stage R1). These data were compared with before wearing (Stage B).

RESULTS

Occlusal force has significant decrement at Stages A1, A3 and A6 after wearing OA5-75, at Stages A3 and A6 after wearing OA5-60, and at Stage A6 after wearing OA5-0. Occlusal contact area has significant decrement at Stages A1, A3 and A6 after wearing OA5-75, and at Stage A6 after wearing OA5-60. Occlusal load center has significant forward displacement at Stages A3 and A6 after wearing OA5-75, and at Stage A6 after wearing OA5-60.

CONCLUSION

To fabricate the appropriate OA in occlusal perspective, it is preferable to set the mandibular position at 45% advancement of maximum protrusion capacity of condyle head in terms of the mandibular positions used in this study.

Review of oral appliances for treatment of sleep-disordered breathing

Between 1982 and 2006, there were 89 distinct publications dealing with oral appliance therapy involving a total of 3,027 patients, which reported results of sleep studies performed with and without the appliance. These studies, which constitute a very heterogeneous group in terms of methodology and patient population, are reviewed and the results summarized. This review focused on the following outcomes: sleep apnea (i.e. reduction in the apnea/hypopnea index or respiratory disturbance index), ability of oral appliances to reduce snoring, effect of oral appliances on daytime function, comparison of oral appliances with other treatments (continuous positive airway pressure and surgery), side effects, dental changes (overbite and overjet), and long-term compliance. We found that the success rate, defined as the ability of the oral appliances to reduce apnea/hypopnea index to less than 10, is 54%. The response rate, defined as at least 50% reduction in the initial apnea/hypopnea index (although it still remained above 10), is 21%. When only the results of randomized, crossover, placebo-controlled studies are considered, the success and response rates are 50% and 14%, respectively. Snoring was reduced by 45%. In the studies comparing oral appliances to continuous positive airway pressure (CPAP) or to uvulopalatopharyngoplasty (UPPP), an appliance reduced initial AHI by 42%, CPAP reduced it by 75%, and UPPP by 30%. The majority of patients prefer using oral appliance than CPAP. Use of oral appliances improves daytime function somewhat; the Epworth sleepiness score (ESS) dropped from 11.2 to 7.8 in 854 patients. A summary of the follow-up compliance data shows that at 30 months, 56–68% of patients continue to use oral appliance. Side effects are relatively minor but frequent. The most common ones are excessive salivation and teeth discomfort. Efficacy and side effects depend on the type of appliance, degree of protrusion, vertical opening, and other settings. We conclude that oral appliances, although not as effective as CPAP in reducing sleep apnea, snoring, and improving daytime function, have a definite role in the treatment of snoring and sleep apnea.

Apnées centrales induites sous traitement par orthèse d’avancée mandibulaire

INTRODUCTION

Mandibular advancement (MA) has emerged over the last decade as an alternative solution to nasal continuous airway pressure (nCPAP) for the treatment of obstructive sleep apnea syndrome (OSAS).

OBSERVATION

We report the case of a patient with history of chronic atrial fibrillation and moderate supine-dependent OSAS in whom central sleep apneas developed during treatment by a bi-bloc MA device. Central apneas increased with the level of MA and preferentially occurred in the supine position. We hypothesized that mouth opening under excessive mandibular advancement in supine position may have led to pharyngeal narrowing at the base of the tongue and potentially unstable ventilation. Sleep fragmentation that enhanced during progressive MA may also have compromised ventilatory control stability in our patient. Finally, chronic atrial fibrillation may have predisposed to central sleep apneas.

CONCLUSION

Our case report highlights the importance of follow-up nocturnal recordings during progressive MA.

Long-term compliance and side effects of oral appliances used for the treatment of snoring and obstructive sleep apnea syndrome

STUDY OBJECTIVE

This study, by means of a mail survey, quantified the compliance with and side effects of the use of an oral appliance for more than five years in patients with snoring or obstructive sleep apnea.

METHODS

A questionnaire was mailed to 544 patients who used an oral appliance for the treatment of snoring or obstructive sleep apnea.

RESULTS

Some 46.1% of the patients returned the questionnaire, 37.8% did not, 15% had an invalid address, and 0.9% were deceased. The mean time period between oral appliance insertion and the return date of these surveys was 5.7 +/- 3.5 years. Of the returned sample, 64.1% were wearing their oral appliance (users). There was no significant difference in the baseline and post-titration respiratory disturbance index between the returned and not-returned groups or between patients who had stopped wearing the oral appliance (nonusers) and users. Within the users group, 93.7% used the oral appliance more than 4 nights per week, 100% wore it more than half of each night, and 95% were satisfied with the treatment. The most frequent reasons why patients discontinued wear were uncomfortable (44.4%), had little or no effect (33.6%), or switched to nasal continuous positive airway pressure (23.3%). Snoring was satisfactorily controlled in 75.6% of users and in 43.2% of nonusers. Side effects, such as dry mouth and tooth and/or jaw discomfort, were more frequent and more severe in the nonusers (P < .05). With oral appliance usage, both users and nonusers reported an increase in temporomandibular joint symptoms, but there was no difference in the degree of change.

CONCLUSIONS

Subjects who were compliant with oral appliance therapy reported long periods of use and adequate control of snoring.

Effect of removable orthodontic appliances on oral colonisation by mutans streptococci in children

Little is known about the effect of removable orthodontic appliances on oral colonisation by mutans streptococci (MS). In the present study, the frequency of isolation and serotype distribution of MS were evaluated in two groups of children, one undergoing therapy with removable appliances and the other not subjected to any kind of orthodontic treatment, respectively. Streptococci isolated from dental plaque samples from both groups of children were identified as mutans streptococci on the basis of their morphological and biochemical properties and were then serotyped in an enzyme immuno-assay using monoclonal antibodies. The number of subjects harbouring MS in their dental plaque was statistically higher in the group of orthodontic children without caries experience (CF) in comparison with CF children of the control group (10/12, 83.3% vs. 15/44, 34%). No clear difference was observed in the distribution of the different MS serotypes between the experimental and control group: S. mutans c,f serotype was the most frequently isolated in both groups of children followed by S. mutans serotype e and S. sobrinus serotype g. Such results suggest that the use of removable appliances may lead to the creation of new retentive areas and surfaces, which favour the local adherence and growth of MS. The data obtained stress the importance of a careful monitoring of patients treated orthodontically for risk of caries development.

Functional and social discomfort during orthodontic treatment--effects on compliance and prediction of patients' adaptation by personality variables

During the course of treatment orthodontic patients frequently endure a number of functional complaints and are anxious about their appearance. The aims of this longitudinal study were to follow the progress of patients' adaptation to discomfort, to elucidate the putative relationship between the type of appliance worn and functional and social discomfort experienced, to study potential predictability by their attitude to treatment and to evaluate the effects of discomfort as predictors of patients' compliance. Eighty-four patients undergoing either removable, functional, or fixed appliance treatment monitored their complaints during the first 7 days of treatment and rated them retrospectively 14 days, and 3 and 6 months after appliance insertion. The most frequent complaints were impaired speech, impaired swallowing, feeling of oral constraint and lack of confidence in public. A significant reduction in the number of complaints was observed between 2 and 7 days after insertion of the appliance. No further differences were revealed after longer periods of appliance wear. The type of appliance had an effect on impaired speech and swallowing. Patients' expectations of favourable treatment performance and appreciation of dental aesthetics were predictive of reported feeling of oral constraint and lack of confidence in public. There was a relationship between the complaints and acceptance of the appliance, as well as between lack of confidence in public and compliance with treatment. The results of this study highlight the importance of patients' attitudes to treatment and of functional and social discomfort associated with appliance wear for the theory and practice of the management of orthodontic patients, and the necessity for early intervention by clinicians.

[A method for preventing and treating maxillodental anomalies related to disordered nose breathing]

Eleven children aged 5-9 years with maxillodental abnormalities were treated using positioners. Negative effects of positioners and activators (increase of dental caries, hygienic index, and acid resistance of the enamel) are analyzed.

Periodontal implications of bonded versus removable retainers

Removable retainers have been used by clinicians since the early years of orthodontic practice. During the last decades, an increasing number of cases are retained with bonded lingual retainers. The current study was performed to evaluate whether significant differences in gingival conditions exist between patients who wear removable or fixed retainers. Differences in build-up of plaque and calculus were also investigated. Maxillary and mandibular measurements were taken at baseline (just before debonding) and 1, 3, and 6 months later, from canine to canine on 36 patients. Among these patients, 22 had fixed retainers, and 14 wore removable retainers. The gingival condition was scored according to three parameters: Modified Gingival Index, bleeding on probing, and gingival crevicular fluid flow. After staining with Diaplac, the Plaque Index was registered. The amount of calculus was measured with a calibrated periodontal probe. Gingival inflammation decreased from baseline throughout the entire period of retention. A comparable limited gingival inflammation was found in the presence of both types of retainers. Slightly more plaque and calculus were present on the lingual surfaces in the fixed retainer group. This did not result in more pronounced gingival inflammation than in the removable retainer group, within the evaluated period.

Increase of the vertical occlusal dimension by means of a removable orthodontic appliance and its effect on craniocervical relationships and position of the cervical spine in children

The aim of this study was to determine the effect of the increase in the occlusal vertical dimension by means of an orthodontic appliance on craniocervical relationships and position of the cervical spine. Thirty children presenting malocclusion were divided into two groups of 15 (a study and a control group). Those in the study group wore an orthodontic appliance to correct cross-bite. The children in the control group had no treatment during the experimental period. Two lateral craniocervical radiographs were taken for each child. The first one was taken in the intercuspal position in both groups. The second radiograph was taken of the study group after four months of wearing the appliance and also of the control group after four months. Cephalometric analysis in the study group showed a significant forward cervical spine position. There were no significant changes in the control group. The changes found in the study group suggest that when there are signs and symptoms of cervical dysfunction in children undergoing long-term orthodontic treatment, it is necessary to make an evaluation of the cervical column position after the insertion of any orthodontic appliance which increases the occlusal vertical dimension.

Orthodontic-prosthetic treatment to replace maxillary incisors exfoliated because of improper use of orthodontic elastics: a case report

This article describes the iatrogenic exfoliation of maxillary central incisors following the improper use of orthodontic elastic bands. The unsecured rubber band had migrated apically and caused an almost "bloodless extraction" of both maxillary central incisors. A combined orthodontic-prosthetic solution was used to replace the lost incisors.

Latex elastic-induced periodontal damage: a case report on the subsequent orthodontic management

Proper management of a malocclusion relies on a basic understanding of the development of the dentition and the craniofacial complex. Diagnosis should only be formulated after all the relevant diagnostic records, including clinical examination and history, are reviewed. Armed with this information, the dentist forms the treatment plan. The mere occurrence of a malocclusion does not constitute a need for treatment. Injudicious intervention can be counterproductive or destructive. Through a case report, the deleterious effects of improper case management and questionable treatment mechanics are highlighted. The subsequent orthodontic management emphasizes the principles and techniques for the successful treatment of the patient in question.

Radiographic evaluation of the effect of orthodontic retraction on the root of the maxillary canine

OBJECTIVES

To evaluate possible apical root resorption following orthodontic retraction of the maxillary canine quantitatively and qualitatively.

METHODS

Twenty maxillary canines in 12 patients were retracted using a prefabricated orthodontic spring. Twenty non-treated mandibular canines from the same patients served as controls. Standardized radiographs were taken of all upper and lower canines before (T0) and after (T2) retraction. Root length and tooth length were measured on the radiographs at T0 and T2, and the root length/tooth length ratio was calculated. Ten orthodontists assessed blind the root apex of the pairs of radiographs taken at T0 and T2 for resorption. Digital subtraction was performed between the pairs of radiographs taken at T0 and T2 and the mean density and the standard deviation of the grey shades of the root apex calculated.

RESULTS

There were no significant differences between root length/tooth length ratio at T0 and T2 for either the maxillary (p = 0.45) or the mandibular canines (p = 0.79). There was considerable variation between observers judgements of root resorption: nine out of ten observers agreed that a resorption had taken place in only one tooth. There were no significant differences between the mean density values in the subtraction images of the upper and lower canines (p = 0.3).

CONCLUSIONS

Quantitative assessment with conventional and subtraction radiography failed to demonstrate root resorption in the maxillary canines. Root resorption could be shown qualitatively in only one tooth. The standardized orthodontic force system used for canine retraction appeared to cause no resorption, or only a small degree of resorption of no clinical relevance.

Effect of chlorhexidine gluconate mouth wash on the plaque microflora in children using intra oral appliances

The effect of 0.2% chlorhexidine mouth wash (Hexidine) on the plaque microflora was evaluated on children wearing intra oral removable appliances. Plaque samples were collected from the enamel sections, both primary and permanent, mounted on the removable appliances. These appliances were worn by 12 children for one week. Plaque was allowed to accumulate on the in situ test sites and on the adjacent natural dentition. At the end of the experimental period the plaque microflora associated with the enamel sections were compared with that obtained from lingual and interproximal areas of the lower molar teeth. It was also compared with a control group of 12 children without an appliance. In addition, the effect of 0.2% chlorhexidine mouth wash on the plaque microflora for the next 14 days was also determined on both the groups. Although some quantitative difference was found between the proportion of isolates obtained from the different enamel surfaces, it was not statistically significant. There was a statistically significant increase in the isolates of plaque microflora after the insertion of removable appliance in children which decreased significantly with the use of 10 ml of 0.2% chlorhexidine gluconate mouth wash twice a day. The study indicates that the primary and permanent tooth specimens mounted on the intra-oral device collected plaque microflora similar to that present on the adjacent natural dentition and that chlorhexidine gluconate mouth wash therapy is effective in reducing plaque microflora in children with removable appliances.

Mechanical assessment of interocclusal clearance

Appropriate design considerations for pediatric or adult appliances are a part of diagnosis as well as therapy. These include occlusal factors. The occlusal considerations warrant accurately accommodating the cast metal framework or wire elements of a removable appliance. A gauge measurement can be accomplished utilizing the device we describe.

The effect of fixed and functional appliances on enamel decalcifications in early Class II treatment

The presence of enamel decalcifications before and after early Class II treatment was examined on 41 subjects and 164 permanent first molars. No new demineralization areas were found in patients wearing only a removable appliance. Of the maxillary molars 6% displayed decalcifications in patients wearing a headgear only: whereas of patients wearing a headgear and biteplate 25% displayed enamel lesions. Eighteen percent of white spot lesions diagnosed before treatment had shown a "reversal phenomenon," whereby the enamel appeared normal after treatment. This process only occurred in the functional appliance group indicating that remineralization was better achieved with an appliance that was capable of being removed from the oral cavity.

[Relationship between TMJ pathology and types of orthodontic treatment]

The Authors report the incidence of temporo-mandibular joint disease in young people which are treated with different type of orthodontic therapy. The incidence is variable according to the absence of orthodontic therapy or the presence of treatment with removable or not removable appliances.

The deep overbite: prevention of trauma

An understanding of the mechanisms by which deep overbite trauma develops will allow interception at an early age of those cases most at risk. Measures may then be taken to prevent progression to the stage where treatment becomes difficult.

[An evaluation of appliance hygiene index on patients wearing removable orthodontic appliance]

The appliance hygiene performance and its relationship with stomatitis lesions were investigated on 124 patients who were using maxillary removable orthodontic appliance. The patients were divided into five groups according to the appliance wearing periods. Appliance hygiene index (AHI) showed no significant difference between the groups except the fifth group and the prevalence of stomatitis was found as 8.9 percent. There was not any significant correlation between the quantity of plaque and the degree of stomatitis.

[The condition of periodontium in children treated with removable orthodontic devices]

The purpose of the study was establishing whether, and if so, which regulatory devices traumatize the parodontal tissues. Clinical examination was done in 60 children treated with functional devices and 20 with mechanical devices before the treatment and 3 to 5 months after treatment beginning. The condition of the parodontium was assessed by means of the gingival index and the periodontal index of Russell. Oral hygiene was assessed using the plaque index. In the light of the obtained results it may be said that removable functional and mechanical devices for teeth regulation caused no pathological changes in parodontal tissues in children aged 7-10 years.