Hair Evaluation in Orthodontic Patients with Oligodontia.

Oligodontia can be isolated or syndromic, associated with other ectodermal abnormalities. The aim of the study was to perform hair examination in orthodontic patients diagnosed with oligodontia with a low clinical expression of symptoms of ectodermal origin. All available orthodontic patients diagnosed with oligodontia in the permanent dentition were enrolled. Hair examination included clinical evaluation of the patients' hair, trichoscopy, trichogram and evaluation of the hair shafts under a polarized light microscope. In total, 25 patients, 18 males and 7 females, aged 6 to 24 years were evaluated for the presence of dental and hair abnormalities. The number of congenitally absent teeth ranged from 6 to 24 teeth and diastemas, microdontia, taurodontism and altered tooth shape were found in 23 patients. Hair disorders were found in 68% of the subjects. Hypotrichosis, the heterogeneity of shaft color and loss of pigment, androgenetic alopecia, telogen effluvium, trichoschisis, pili canaliculi, trichorrhexis nodosa and pseudomoniletrix were observed. Trichoscopy and trichogram are valid non-invasive diagnostic tests which could be used to differentiate between isolated and syndromic oligodontia in patients with a low clinical expression of ectodermal symptoms.

Dentofacial characteristics of children and adolescents with foetal alcohol spectrum disorders: a comparison with matched controls.

BACKGROUND: Foetal alcohol spectrum disorders (FASD) include somatic and neurological developmental disturbances after prenatal alcohol exposure, including facial anomalies. However, the knowledge of the orthodontic skeletal and dental cephalometric relations in this group is limited. The aim of the study was to assess the dentofacial characteristics of children and adolescents with FASD and to compare them with a matched control group. METHODS: The study group comprised all available children and adolescents diagnosed with FASD (> 7 years of age) in whom good quality cephalograms were available. The control group comprised non-syndromic, orthodontically untreated children with normal occlusion and skeletal relations matched with age and gender. Cephalometric analysis included eighteen linear and angular measurements. The general linear model for repeated measures regarding age, gender and the type of FASD was applied. RESULTS: The group with FASD included 35 individuals (21 girls and 14 boys) aged 7-18 years including 21 with foetal alcohol syndrome. The mean age in the study and the control group was 12.8 years (SD, range 3.2, 7.1-18.1) and 13.0 (SD, range 2.9, 9.1-18.1), respectively. Statistically significant differences between the groups were found in 15 out of 18 of the cephalometric measurements (83%). In children with FASD the mandible was more retrusive, the incisors were more proclined and the mandibular incisors and the lips were more protruded when compared with controls. There was no significant evidence of an influence of age, gender or FASD type. CONCLUSIONS: Dentofacial characteristics of children and adolescents with FASD significantly differ from controls. Early orthodontic diagnosis and prophylaxis should play a part of the interdisciplinary care of patients in this group.

Comparisons of Dental Anomalies in Orthodontic Patients with Impacted Maxillary and Mandibular Canines.

To assess the presence and possible associations between the type of dental anomalies and maxillary and mandibular canine impactions in orthodontic patients treated for canine impaction, panoramic radiographs of orthodontic patients treated for canine impaction were assessed for the presence of associated dental anomalies. A random sample of orthodontic patients without canine impaction matched for age and gender served as controls. Descriptive and exact inferential statistics were implemented in order to assess potential associations between canine impaction and dental anomalies. A total of 102 orthodontic patients with 70 maxillary (MaxCI) and 32 mandibular (ManCI) canine impactions were assessed. The control group included 117 orthodontic patients. Dental anomalies were present in more than 50% of patients with impacted canines and in 20% of the controls. Tooth agenesis was significantly more common in the MaxCI group when compared to the ManCI group, while supernumerary teeth and canine transmigration were registered more often in the ManCI group. When compared to the control group, peg-shaped maxillary lateral incisors and tooth agenesis were significantly more prevalent in the MaxCI group, while canine transmigration, supernumerary teeth, the agenesis of mandibular incisors and tooth transpositions were significantly more prevalent in the ManCI group. The impaction of other teeth was significantly more common in both canine impaction groups when compared to the controls. The prevalence of dental anomalies in orthodontic patients with impacted canines was higher than in orthodontic patients without canine impaction. Different types of tooth anomalies were found in the MaxCI and ManCI groups.

Application of Artificial Intelligence (AI) in a Cephalometric Analysis: A Narrative Review.

In recent years, the application of artificial intelligence (AI) has become more and more widespread in medicine and dentistry. It may contribute to improved quality of health care as diagnostic methods are getting more accurate and diagnostic errors are rarer in daily medical practice. The aim of this paper was to present data from the literature on the effectiveness of AI in orthodontic diagnostics based on the analysis of lateral cephalometric radiographs. A review of the literature from 2009 to 2023 has been performed using PubMed, Medline, Scopus and Dentistry & Oral Sciences Source databases. The accuracy of determining cephalometric landmarks using widely available commercial AI-based software and advanced AI algorithms was presented and discussed. Most AI algorithms used for the automated positioning of landmarks on cephalometric radiographs had relatively high accuracy. At the same time, the effectiveness of using AI in cephalometry varies depending on the algorithm or the application type, which has to be accounted for during the interpretation of the results. In conclusion, artificial intelligence is a promising tool that facilitates the identification of cephalometric landmarks in everyday clinical practice, may support orthodontic treatment planning for less experienced clinicians and shorten radiological examination in orthodontics. In the future, AI algorithms used for the automated localisation of cephalometric landmarks may be more accurate than manual analysis.

Availability of Third Molars as Donor Teeth for Autotransplantation to Replace Congenitally Absent Second Premolars in Children and Young Adults.

The aim of the study was to assess the presence and distribution of third molars (M3) regarding their autotransplantation in patients with congenital absence of second premolars (PM2). Additionally, M3 development in relation to patients' age and gender was investigated. Panoramic radiographs of non-syndromic patients with at least one congenitally absent PM2 were used to assess the localization and number of missing PM2 and the presence or absence of M3 (minimum age 10 years). The alternate logistic regression model was applied to analyze associations between the presence of PM2 and M3. A total of 131 patients with PM2 agenesis were identified (82 females, 49 males). At least one M3 was present in 75.6% and all M3 were present in 42.7% of patients. A statistically significant association between the number of PM2 and M3 agenesis was found; the effects of age and gender were not significant. More than half of M3 in patients between 14-17 years old had completed » of their root development. The congenital absence of maxillary PM2 was associated with the absence of maxillary PM2, M3, and no correlation was found in the mandible. In patients with PM2 agenesis, at least one M3 is often present and can be considered as a donor tooth for autotransplantation.

Survey of patients and parents on the autotransplantation of developing premolars to replace traumatised maxillary incisors.

BACKGROUND/AIM: There is a little research on the experiences and opinions of patients who have had autotransplantation of a tooth. The aim of the study was to assess the satisfaction of patients who underwent the autotransplantation of a developing premolar to replace a traumatised maxillary central incisor. MATERIALS AND METHODS: Eighty patients (with a mean age of 10.7-years) and 32 parents were surveyed with 13 and 7 questions, respectively, to determine their opinions about the surgery, post-operative period, orthodontic and restorative treatment they had received. RESULTS: Patients and their parents were very satisfied with the outcomes of the autotransplantation treatment. The majority of patients and all parents declared that they would choose this treatment again if needed. Patients who already had aesthetic restoration of the transplanted toothscored significantly better in position, similarity to other teeth, alignment and aesthetics, when compared to patients before restoration of the premolar to the shape of incisor. Patients after orthodontic treatment considered the alignment of the transplanted tooth between the adjacent teeth as better when compared to patients before or during their orthodontic treatment. CONCLUSIONS: Autotransplantation of developing premolars to replace traumatized maxillary central incisors proved to be a well-accepted treatment option. A delay of restoration of the transplanted premolars to the shape of the maxillary incisors did not have a negative impact on the satisfaction with the treatment.

Pulp Revascularization After Autotransplantation of the Mandibular Canines With Partially Resected Roots: Report of 5 Cases With Follow-ups Between 26 and 80 Months.

INTRODUCTION: Transmigrated (migrated through the midline) mandibular canines constitute a treatment challenge. Advanced transmigration can be successfully treated by autotransplantation. In developing canines, pulp revascularization is typical after transplantation. On the contrary, the pulp of teeth with completed apex formation does not undergo revascularization. In this case, root canal treatment becomes compulsory and decreases the success of autotransplantation. The aim of this observational retrospective study was to evaluate whether partial resection of the root (performed during the autotransplantation of mature canines) would enable revascularization of the pulp after the surgery. METHODS: Five transmigrated mandibular canines with complete apex formation before the surgery were evaluated. During the autotransplantation surgery, the resection of 2 to 4 mm of the root apex was performed to open the path for revascularization of the pulp after surgery. The transplanted teeth were observed during healing after the surgery for the presence of pulp obliteration. Clinical and radiographic examinations were performed. RESULTS: All treated canines survived the minimum observation period of 2 years (ranging from 26 to 80 months, mean: 55 months) without pulp healing complications. The survival was 100%, and the success was 80%. In one canine, the external cervical root resorption was diagnosed and treated 1 year after the surgery. At the final examination, transplanted canines presented radiographic features of pulp obliteration, normal mobility, and healthy periodontal tissues. CONCLUSIONS: The surgical protocol proved to be successful in promoting revascularization to maintain pulp vitality, in all cases. The outcomes confirm that autotransplantation, combined with the resection of the root, constitutes a valid treatment for mature ectopic canines.

World Federation of Orthodontists guidelines for postgraduate orthodontic education.

Advanced dental education programs in orthodontics and dentofacial orthopedics require an extensive and comprehensive evidence-based experience, which must be representative of the current didactic and technical advancements. Over the past 25 years, the World Federation of Orthodontists (WFO) has placed emphasis in the support for the recognized orthodontic specialty training programs in every region of the world. In its early years, the WFO developed general principles for specialty education that culminated in the first comprehensive curriculum recommendations, i.e., the WFO Guidelines for Postgraduate Orthodontic Education, which was published in February 2009. In view of the significant changes in the specialty of orthodontics, the WFO has revised and updated its previous document to reflect the expanded scope and demands of current orthodontic education and practice. The members of the task force participated in a thorough revision of the guidelines and created a new document that takes into consideration the didactic, clinical, and the appropriate physical facilities to provide clinical care, study, and research areas. Although it is recognized that there will be variations in teaching and faculty assets, as well as facilities, access to materials, and equipment, the aim of the WFO Educational Guidelines is to provide the minimum program requirements necessary to provide orthodontic specialty residents the educational experience that prepares them to deliver the best level of orthodontic treatment for their patients. It is recommended that these guidelines be used universally by orthodontic specialty program educators and related educational, scientific, and administrative institutions to evaluate and compare their curriculum to a world standard.

Identifying important prognostic factors and outcomes for autotransplantation of developing teeth: Clinicians' perspectives.

BACKGROUND/AIM: Variability in the outcome measures used to assess the success of tooth autotransplantation presents challenges for combining data to examine the success of the technique. Reaching agreement on the most important outcomes will enable routine procedural and follow-up data to be collected in a standardised way. In turn this will promote greater data synthesis to evaluate outcomes and examine which procedural techniques influence outcome. The aim of this study was to identify which prognostic factors and outcomes are most important to clinicians with experience in autotransplantation of developing teeth. METHODS: The Delphi method was used to build consensus on the most important prognostic factors and outcomes. Item identification involved a systematic literature review and review of current clinical datasets in use. A two-round Delphi questionnaire was undertaken with clinicians providing tooth autotransplantation, followed by a consensus meeting to finalise the most important items. RESULTS: Outcomes and prognostic factors were identified from the systematic review (82 studies and eight reviews), one guideline and three existing clinical datasets. Patient interviews and a clinician survey added a number of items that would not have been identified from the literature only. A total of 56 outcomes and 93 prognostic factors were included for rating in the Delphi questionnaire. The Delphi questionnaire was completed by 15 respondents in round one and 13 respondents in round two. The consensus meeting was attended by nine participants. The final items that were judged to be most important included 29 outcomes (25 clinical, three patient-reported and one service delivery) and 49 prognostic factors (18 patient characteristics, four presurgical, 17 surgical and 10 postsurgical). Clinical outcomes were consistently rated higher than patient-reported outcomes. CONCLUSIONS: The clinical outcomes rated as the most important were transplant survival and reason for failure, outcomes relating to pulp health, different types of resorption and evidence of infection (suppuration). Important patient-reported outcomes were satisfaction with overall treatment experience, and outcome and quality of life related to function of the transplanted tooth. Procedural information rated as being the most important related to the donor tooth: stage of root development, method for surgical removal and storage and condition of the donor tooth root surface following removal.

Orthodontic evaluation of children and adolescents with different types of Foetal Alcohol Syndrome Disorders.

OBJECTIVE: To assess general and oral health status, including the presence of malocclusion and orthodontic treatment needs, in children and adolescents with FASD in relation to different types of this disorder. SETTING AND SAMPLE POPULATION: A total of 67 participants (29 males and 38 females) aged 2.5-17.8 years with confirmed diagnosis of FASD were included. MATERIALS AND METHODS: The participants were divided into three subgroups: foetal alcohol syndrome (FAS), partial foetal alcohol syndrome (PFAS) and alcohol-related neurodevelopmental disorders (ARND). General health, oral health status, history of dental trauma, presence of dysfunctions or parafunctions, and occlusion were examined. Additionally, the Index of Orthodontic Treatment Need (IOTN) index was calculated. Selected variables were compared to the results obtained from a national monitoring survey on the oral health conditions in Poland. RESULTS: In children and adolescents with FASD, a number of systemic anomalies including alimentary, neurological and musculoskeletal disorders were present. Dysfunctions and parafunctions such as mouth breathing and thumb sucking were frequently recorded. Children with FASD had an increased prevalence of distal occlusion and crossbite compared to the general population. Malocclusions were more often identified in the FAS group. No significant differences in the IOTN between different FASD groups were found. Borderline need for orthodontic treatment was more frequent in children with FASD compared to controls. CONCLUSION: Early screening for the presence of dysfunctions/parafunctions and malocclusions in children with FASD is recommended, so that orthodontic prophylaxis and state-funded orthodontic care programmes for these children are implemented.

Effect of Tooth Agenesis on Mandibular Morphology and Position.

Congenital missing teeth (OMIM #106600) is the most common dental abnormality. The aim of the study was to evaluate the effects of tooth agenesis on the total mandibular length, length of the mandibular body and alveolar process, and the mandibular anteroposterior position. The material was obtained from the Department of Orthodontics, Medical University of Warsaw. The study group included 116 patients aged 9-18 years with a congenital absence of at least two permanent tooth buds in the maxilla and/or mandible (mean: 6.2 teeth missing/patient). All patients were Caucasians: 68 (59%) females and 48 (41%) males. The control group included 115 patients without tooth agenesis matched with the age and gender of the study group. A cephalometric analysis was performed, and it was focused on assessing anteroposterior mandibular measurements. This assessment was based on 17 measurements (12 linear and 5 angular). Statistical analysis of the cephalometric measurements between the study group and the control group showed significant changes regarding selected mandibular measurements. Tooth agenesis does not affect the total length of the mandible and the length of the mandibular body, but it might reduce the length of the mandibular arch length and result in a more retrusive mandibular position.

Comparisons of different treatment methods and their outcomes for impacted maxillary and mandibular canines: A retrospective study.

BACKGROUND: Impacted canines may pose a functional and an esthetic problem for patients and can affect neighboring incisors. The aim of the study was to compare different treatment methods and their outcomes for impacted maxillary and mandibular canines. METHODS: The authors included 102 patients with 118 impacted canines (82 maxillary and 36 mandibular canines). Impacted canine were confirmed during clinical and radiologic examinations. Eighty-five patients (83%) with 97 impacted canines started the treatment. The authors analyzed treatment types and outcomes. Two maxillary and 4 mandibular canines were scheduled for extraction. RESULTS: Orthodontic extrusion was used most frequently to treat impacted maxillary canines (89%), whereas orthodontic extrusion and transalveolar transplantation were performed most frequently in impacted mandibular canines (33% and 37.5%, respectively). The treatment was successful in 96% of the maxillary and 95% of the impacted mandibular canines. CONCLUSIONS: Different methods were used for impacted maxillary and mandibular canines, but their overall success rate was high. PRACTICAL IMPLICATIONS: Successful outcome is determined via a well-planned and carefully executed orthodontic and surgical treatment. Early diagnosis is pivotal in facilitating spontaneous canine eruption and implementing transalveolar transplantation in a timely way.

Status of the alveolar bone after autotransplantation of developing premolars to the anterior maxilla assessed by CBCT measurements.

BACKGROUND/AIMS: Autotransplantation of developing premolars is an established treatment to replace missing teeth in the anterior maxilla in growing patients with a reported success rate of over 90%. The normal shape of the alveolus is observed after transplantation, but data on the presence and amount of alveolar bone after healing has not been previously reported. The aim of this study was to look for potential differences in alveolar bone dimensions between sites where autotransplanted premolars replaced missing incisors and control sites of contralateral incisors. MATERIAL/METHODS: There were 11 patients aged between 10 and 12 years five months (mean age: 10 years and 7 months) who underwent autotransplantation of a premolar to replace a central incisor. Cone Beam Computed Tomography (CBCT) performed at least 1 year after transplantation served to evaluate bone at sites of autotransplanted premolars and controls (contralateral maxillary central incisor). The thickness of the labial bone, plus the height and width of the alveolar process were measured on scans and compared at transplant and control sites. RESULTS: Mean thicknesses of the labial bone at the transplant and control sites were 0.78 mm and 0.82 mm respectively. Mean alveolar bone height was 15.15 mm at the transplant sites and 15.12 mm at the control sites. The mean marginal thickness of the alveolus was 7.75 mm at the transplant sites and 7.98 mm at the control sites. Mean thicknesses of the alveolus for half of its vertical dimension at the transplant and control sites were 7.54 mm and 8.03 mm, respectively. CONCLUSION: The mean values of bone thickness, width and height of the alveolar process at sites of transplanted premolars were comparable to the mean values for the control incisors. Successful autotransplantation of developing premolars to replace missing central incisors allowed preservation of alveolar bone in the anterior maxilla.

Cancer survivors present significantly lower long-term stability of orthodontic treatment: a prospective case-control study.

BACKGROUND/OBJECTIVES: The aim of the study was to compare the stability of orthodontic treatment in cancer survivors who had been treated with cytotoxic drugs with a generally healthy control group. MATERIALS/METHODS: The study included 52 cancer survivors treated orthodontically and 52 healthy control subjects matched for age, gender, and malocclusion. The weighted Peer Assessment Rating (w-PAR) index, the Index of Complexity, Outcome and Need (ICON) were assessed before treatment, after the treatment, and at the 3-year follow-up. Patients Satisfaction Score was assessed after the treatment and at the 3-year follow-up. A repeated analysis of variance test was used to check the statistical significance between the scores. RESULTS: Ideal occlusion was achieved in all patients. The mean w-PAR and ICON values were significantly reduced in both groups after the end of the orthodontic treatment with no significant differences between the groups regarding the obtained results. However, after the 3-year follow-up, only the cancer survivors' group presented statistically significant (P < 0.001) increase of the w-PAR and ICON values comparing to the values obtained at the end of the treatment. There was no significant change in Patients' Satisfaction Score within 3 years after treatment. LIMITATIONS: The limited size of the study sample as well as different types of oncological diagnoses could have had an impact on the final results of the study. CONCLUSIONS/IMPLICATIONS: Previous cytotoxic drug treatment significantly decreases the stability of orthodontic treatment among the cancer survivors, particularly within first 12 months after the end of the treatment.

Comparison of Oral Health Impact Profile (OHIP-14) Values in Cancer Survivor Patients Treated Orthodontically with Either Rapid or Standard Duration Protocols of Treatment-A Prospective Case-Control Study.

BACKGROUND: The aim of the study was to compare the oral-health-related quality of life (OHRQoL) between cancer survivors: with rapid orthodontic treatment (TX) (up to 12 months) and standard TX (orthodontic treatment time longer than 16 months). METHODS: There were 76 cancer survivors (48 women and 28 men) allocated into groups with rapid (36 people) or standard (40 people) duration of TX. OHRQoL was assessed on the basis of Oral Health Impact Profile (OHIP-14) values, measured before TX, 2 weeks and 3 months after the onset of TX, and after the end of TX. A repeated ANOVA test was used to check the statistical significance between the scores. RESULTS: There were no significant differences regarding the OHIP-14 values between the examined groups at all stages of the examination. Both groups presented significant (p < 0.001) improvement of the values of OHRQoL at the end of TX comparing to the values achieved before the onset of TX. CONCLUSIONS: Duration of orthodontic treatment by itself had no impact on oral-health-related quality of life.

Quality of Life in Orthodontic Cancer Survivor Patients-A Prospective Case-Control Study.

Background: The aim of the study was to compare the quality of life (QoL) of cancer survivors with a control group of healthy subjects before, during, and after the orthodontic treatment. Methods: Consecutive cancer survivors (40 people) who were looking for orthodontic treatment between 2008 and 2015 were enrolled into the study. Healthy orthodontic patients matched for age (±4 years), sex, and malocclusion served as controls. The 14-item version of the Oral Health Impact Profile was used to assess the effect of orthodontic treatment on QoL before, during, and after the orthodontic treatment. Results: There were no significant differences between both groups regarding the cast model, cephalometric analysis, and photographic documentation analysis. There was a significant worsening of QoL after the onset of the orthodontic treatment with a significant improvement after the treatment. Male cancer survivor patients reported significantly lower QoL during the treatment time, which was not observed in the male control group. Conclusions: The outcome of orthodontic treatment in cancer survivors did not differ from the healthy orthodontic patients. The orthodontic treatment had an impact on the oral health quality of life both in the cancer and the control groups with a significantly higher impact in male cancer survivor patients.

The retrospective study of 93 patients with transmigration of mandibular canine and a comparative analysis with a control group.

OBJECTIVES: The aim of this study was to evaluate characteristics of patients with unilateral transmigration of a mandibular canine in the largest study group presented until now. MATERIALS AND METHODS: The study group consisted of 93 patients with unilateral transmigration of mandibular canine; the control group included 85 non-affected patients. Type of transmigration, status of deciduous and permanent canines, prevalence of missing teeth, class of occlusion, and space conditions were assessed to draw comparisons between groups. RESULTS: In this study, 64.5 per cent patients presented type 1 of transmigration; types 2, 3, 4, and 5 were present in, respectively, 23.7, 5.4, 4.3, and 2.1 per cent patients. There was a clear, statistically significant difference (P < 0.0001) between the mean crown and apex migration and angulation for the three groups of canines (transmigrated, contralateral, and control), whereas no differences were observed for the total number of permanent teeth present. In the study group, 73.1 per cent patients retained their primary canine on the affected side and 18.3 per cent on the contralateral side; in the control group, 22.3 per cent subjects had at least one primary canine. There was a statistically significant difference in the distribution of types of malocclusion between the study and the control groups. CONCLUSIONS: Transmigration of mandibular canine was associated with the presence of retained primary canine on the affected side, higher mesial tilting of contralateral mandibular canine when compared to the canines in the control group. Additionally, higher prevalence of Angle's Class I occlusion in patients with canine transmigration was recorded.

Study on site-specific expression of bone formation and resorption factors in human dental follicles.

We sought to investigate site-specific expression of bone-regulatory factors expressed by human dental follicles and to compare the stimulated expression of tumour necrosis factor (ligand) superfamily, member 11/tumour necrosis factor receptor superfamily, member 11b (RANKL/OPG) in human dental follicle cells (HDFCs) from different patients. Analysis of bone-regulatory markers in follicles from 12 different study participants was performed using RT-qPCR and immunofluorescence; apical and coronal segments from each dental follicle were processed independently. Four additional dental follicles were used for cell cultures; HDFCs were precultured in osteogenic medium to initiate differentiation and thereafter cultured with 10-6 M forskolin (FSK) to activate the protein kinase cAMP (PKA/cAMP) signalling pathway and induce RANKL/OPG expression. We demonstrate that RANKL expression is significantly higher in the coronal part of follicles than in the apical part. High levels of collagen type 1 (COL1), alkaline phosphatase (ALP) and Gap-junction protein, alpha 1, 43 kDa (CX43) were expressed, whereas expression of Sp7 transcription factor (OSX), bone morphogenetic protein 2 (BMP2), colony-stimulating factor 1 (CSF-1), chemokine (C-C motif) ligand 2 (MCP1), and OPG was low in all samples. The immunofluorescence localization of CSF-1, MCP1, osteocalcin (OCN), RANKL, and BMP2 was not specific for either part of the follicles. In conclusion, a consistently high expression of CX43 suggests that gap-junction communication in HDFCs is essential for the eruption process. Furthermore, the induced expression of RANKL in HDFCs varies significantly between individuals and may relate to clinical variations in tooth eruption.