Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 77
Filtrar
1.
Artigo em Inglês | MEDLINE | ID: mdl-33906772

RESUMO

Bone-borne rapid maxillary expansion distraction devices are used to achieve a more skeletal expansion and to avoid dental side effects of conventional expanders such as tipping of anchorage teeth. In this article, we report the use of a prefabricated expander fixed on 2 mini-implants in the anterior palate. This allows for the insertion of the mini-implants and the expander to occur without the need for an impression or any laboratory procedures. Especially when aligners are going to be used, the use of a mini-implant-borne expander seems to be reasonable because the expander can be left in place as a skeletal retainer during the aligner finishing.

3.
Head Face Med ; 17(1): 3, 2021 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-33531044

RESUMO

BACKGROUND: Orthodontic root resorptions are frequently investigated in small animals, and micro-computed tomography (µCT) enables volumetric comparison. Despite, due to overlapping histograms from dentine and bone, accurate quantification of root resorption is challenging. The present study aims at (i) validating a novel automated approach for tooth segmentation (ATS), (ii) to indicate that matching of contralateral teeth is eligible to assess orthodontic tooth movement (OTM) and root resorption (RR), (iii) and to apply the novel approach in an animal trial performing orthodontic tooth movement. METHODS: The oral apparatus of three female mice were scanned with a µCT. The first molars of each jaw and animal were segmented using ATS (test) and manually (control), and contralateral volumes were compared. Agreement in root volumes and time efficiency were assessed for method validation. In another n = 14 animals, the left first upper molar was protracted for 11 days at 0.5 N, whereas the contralateral molar served as control. Following ATS, OTM and RR were estimated. RESULTS: ATS was significantly more time efficient compared to the manual approach (81% faster, P < 0.01), accurate (volume differences: - 0.01 ± 0.04 mm3), and contralateral roots had comparable volumes. Protracted molars had significantly lower root volumes (P = 0.03), whereas the amount of OTM failed to reveal linear association with RR (P > 0.05). CONCLUSIONS: Within the limits of the study, it was demonstrated that the combination of ATS and registration of contralateral jaws enables measurements of OTS and associated RR in µCT scans.


Assuntos
Reabsorção da Raiz , Animais , Feminino , Camundongos , Dente Molar/diagnóstico por imagem , Roedores , Reabsorção da Raiz/diagnóstico por imagem , Técnicas de Movimentação Dentária , Raiz Dentária , Microtomografia por Raio-X
5.
Prog Orthod ; 21(1): 5, 2020 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-32064547

RESUMO

BACKGROUND: In dental implantology, the development of stability over time is a well-investigated topic. In case of orthodontic mini-implants, quantitative data for long-term stability is not available yet. This study aims to clinically investigate the long-term stability of mini-implants inserted in the midsagittal suture of the anterior palate. Moreover, the influence of the length of implants was elucidated. The stability of 2 × 9 and 2 × 11 mm mini-implants after orthodontic treatment (9 mm, 2.84 years ± 1.25 years; 11 mm, 3.17 years ± 0.96 years) was assessed by resonance frequency analysis (RFA). The obtained long-term pieces of data were compared with each other (9 mm vs 11 mm), as well as with the data from the matched early stability groups, to assess the initial and early secondary stability after the insertion from previous clinical trials. RESULTS: For both lengths, the long-term stability (2 × 9 mm, 25.12 ± 7.11, n = 21; 2 × 11 mm, 24.39 ± 5.82, n = 18) was significantly lower than primary stability (2 × 9 mm, 36.14 ± 6.08, n = 19; 2 × 11 mm, 33.35 ± 3.53, n = 20). The differences within the groups disappeared over the initial healing period: after 4 weeks for the 2 × 9 mm implants and after 2 weeks for the 2 × 11 mm implants. Also, the 2 × 9 mm and 2 × 11 mm implants showed comparable long-term stability values. CONCLUSION: The stability of midpalatal mini-implants does not change in the long term after the initial healing period. Moreover, 2 × 9 mm mini-implants seem to be appropriate for orthodontic anchorage, as the stability of 2 × 11 mm implants is not higher. Therefore, owing to lower invasiveness, 2 × 9 mm implants should be preferred.


Assuntos
Implantes Dentários , Procedimentos de Ancoragem Ortodôntica , Palato , Análise de Frequência de Ressonância , Cicatrização
6.
Am J Orthod Dentofacial Orthop ; 157(2): 165-171, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32005467

RESUMO

INTRODUCTION: The initial stability of orthodontic mini-implants is well investigated over a period of 6 weeks. There is no clinical data available dealing with the long-term stability. The aim of this study was the assessment of long-term stability of paramedian palatal mini-implants in humans. METHODS: Stability of 20 implants was measured after removal of the orthodontic appliance (sliding mechanics for sagittal molar movement 200 cN each side) before explantation (T4) using resonance frequency analysis (RFA). Data were compared with a matched group of 21 mini-implants assessing the stability immediately after insertion, and after 2, 4, and 6 weeks (T0-T3). The mini-implants used in this study were machined self-drilling titanium implants (2.0 × 9.0 mm). Gingival thickness at the insertion site was 1-2 mm. RESULTS: The implant stability quotient (ISQ) values before removal of the implant at T4 were 25.2 ± 2.9 after 1.7 ± 0.2 years and did not show a statistically significant change over time compared with the initial healing group (T0-T3). CONCLUSIONS: Comparing the stability of mini-implants just after completion of the healing period and at the end of their respective usage period revealed no significant difference. An increase of secondary stability could not be detected. The level of stability seemed to be appropriate for orthodontic anchorage.


Assuntos
Implantes Dentários , Procedimentos de Ancoragem Ortodôntica , Estudos Transversais , Humanos , Palato , Titânio
8.
Eur J Orthod ; 42(3): 270-280, 2020 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-31605613

RESUMO

OBJECTIVE: This study aimed to assess oral health-related quality of life (OHRQoL) in relation to associated covariates in orthodontic patients of different age groups (children, adolescents, and adults) in a cross-sectional study. METHODS: A total of 898 subjects (50.6% females, 49.4% males; mean age 16.89 years) undergoing orthodontic treatment anonymously completed the German version of the Oral Health Impact Profile (OHIP-G14) to assess OHRQoL in addition to completing 23 other items. Descriptive, exploratory statistical analysis and multiple linear regression modelling were performed. RESULTS: The mean score of the OHIP-G14 was 8.3 for the 6- to 11-year olds, 8.9 for the 12- to 17-year olds, and 12.6 for adults. Physical pain (Subscale 2) was the highest factor in all groups. Additionally, a relevant factor was Subscale 3 (psychological discomfort). A linear regression model showed that, in the adolescent group, aesthetics in combination with pain had a significant negative influence on OHRQoL, whereas, in the adult group, function in combination with pain showed the same significant negative influence. Second, except for the children, fixed appliances had a significant negative effect on OHRQoL compared to removable appliances. CONCLUSIONS: Our study showed that the majority of the 6- to 11-year olds and 12- to 17-year olds reported a good OHRQoL. Nevertheless, adolescents and adults who reported aesthetic/pain and function/pain problems, respectively, as reasons for orthodontic treatment showed a significant occurrence for reduced OHRQoL. Fixed appliances, in comparison with removable appliances, also resulted in a significant reduction in OHRQoL for both groups.


Assuntos
Ortodontia , Qualidade de Vida , Adolescente , Adulto , Criança , Estudos Transversais , Estética Dentária , Feminino , Humanos , Masculino , Saúde Bucal , Inquéritos e Questionários
9.
J Orofac Orthop ; 80(6): 292-303, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31578595

RESUMO

PURPOSE: The mechanical properties of orthodontic aligners made from thermoplastic polymers decrease over time in the intraoral milieu. However, there is a lack of information on this topic in the literature. Thus, the elastic properties of polyethylene terephthalate glycol (PETG) aligner films were investigated in vitro under extreme temperature changes simulated by thermocycling, environmental temperature and water absorption. MATERIALS AND METHODS: A total of 60 specimens made from PETG aligner films (CA Clear Aligner, Scheu Dental, Iserlohn, Germany) were divided into three groups (immersed in distilled water, subjected to accelerated ageing by thermocycling, control). These groups were again divided and tensile testing was performed for all groups at 22 and at 37 °C. Young's modulus (E), 0.2% offset yield strength (Rp02) and ultimate tensile strength (UTS) were evaluated. Water absorption was determined using an analytical scale. RESULTS: All treated specimens showed water absorption, whereby specimens that were thermocycled absorbed 48% more water than the immersed ones. Young's modulus and UTS were significantly lower for all three groups at 37 °C compared to the corresponding groups tested at 22 °C. Thermocycled and immersed groups showed a significantly lower Young's modulus compared to the control group tested at the same temperature. The mean Rp02 was statistically different when comparing the control group tested at 22 °C to the one tested at 37 °C. CONCLUSIONS: The results of this study add to the understanding of the clinically well-known degradation of orthodontic aligners during wear time. Extreme alternating temperatures along with warming up to intraoral temperature and water absorption can reduce the material's Young's modulus and may therefore promote a decrease of resulting orthodontic forces.


Assuntos
Envelhecimento , Água , Módulo de Elasticidade , Alemanha , Teste de Materiais , Polietilenoglicóis , Polietilenotereftalatos , Resistência à Tração
10.
Am J Orthod Dentofacial Orthop ; 156(3): 345-354, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31474264

RESUMO

INTRODUCTION: Orthodontic mini-implants are frequently used to provide additional anchorage for orthodontic appliances. The anterior palate is frequently used owing to sufficient bone quality and low risk of iatrogenic trauma to adjacent anatomical structures. Even though the success rates in this site are high, failure of an implant will result in anchorage loss. Therefore, implants should be placed in areas with sufficient bone quality. The aim of the present study was to identify an optimal insertion angle and position for orthodontic mini-implants in the anterior palate. METHODS: Maxillary cone-beam computed tomographic (CBCT) scans from 30 patients (8 male, 22 female, age 18.6 ± 12.0 years) were analyzed. To assess the maximum possible length of an implant, a 25-reference-point grid was defined: 5 sagittal slices were extracted along the median plane and bilaterally at 3 mm and 6 mm distances, respectively. Within each slice, 5 dental reference points were projected to the palatal curvature at the contact point between the cuspid (C) and first bicuspid (PM1), midpoint of PM1, between PM1 and PM2, midpoint of PM2, and between PM2 and the first molar (M1). Measurements were conducted at -30°, -20°, -10°, 0°, 10°, 20°, and 30° to a vector placed perpendicular to the local palatal curvature. Statistical analysis was conducted with the use of R using a random-effects mixed linear model and a Tukey post hoc test with Holm correction. RESULTS: High interindividual variability was detected. Maximum effective bone heights were detected within a T-shaped area at the midpoint of PM1 and contact point PM1-PM2 (P < 0.01). Within the anterior region a posterior tipping was advantageous, whereas in the posterior regions an anterior tipping was beneficial (P < 0.01). In the middle of the median plane, tipping did not reveal a significant influence. No gender- or age-related differences were observed. CONCLUSIONS: Within the limitations of this study, optimal insertion positions were found within a T-shaped area at the height of PM1-PM2 in the anterior palate. In general, a posterior tipping was beneficial at anterior positions, and an anterior tipping appeared beneficial at posterior positions. High interindividual variation was found and should be carefully considered by the clinician.


Assuntos
Tomografia Computadorizada de Feixe Cônico/métodos , Implantes Dentários , Maxila/anatomia & histologia , Maxila/diagnóstico por imagem , Procedimentos de Ancoragem Ortodôntica/métodos , Palato/anatomia & histologia , Palato/diagnóstico por imagem , Adolescente , Adulto , Análise de Variância , Dente Pré-Molar , Parafusos Ósseos , Criança , Estudos Transversais , Dente Canino , Feminino , Humanos , Incisivo/anatomia & histologia , Incisivo/diagnóstico por imagem , Masculino , Maxila/cirurgia , Dente Molar , Osso Nasal/anatomia & histologia , Osso Nasal/diagnóstico por imagem , Procedimentos de Ancoragem Ortodôntica/instrumentação , Desenho de Aparelho Ortodôntico , Palato/cirurgia , Adulto Jovem
11.
Clin Oral Implants Res ; 30(12): 1179-1189, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31494964

RESUMO

OBJECTIVES: Whereas stationary stability of implants has been postulated for decades, recent studies suggested a phenomenon termed implant migration. This describes a change in position of implants as a reaction to applied forces. The present study aims at employing image registration of in vivo micro-CT scans from different time points and to assess (a) if migration of continuously loaded implants is possible and (b) migration correlates with the force magnitude. MATERIAL AND METHODS: Two customized machined implants were placed in the dorsal portion of caudal vertebrae in n = 61 rats and exposed to standardized forces (0.5 N, 1.0 N, and 1.5 N) applied through a flat nickel-titanium contraction spring, or no forces (control). Micro-CT scans were performed at 0, 1, 2, 4, 6, and 8 weeks after surgery. The baseline image was registered with the forthcoming scans. Implant migration was measured as the Euclidean distance between implant tips. Bone remodeling was assessed between the baseline and the forthcoming scans. RESULTS: The findings confirmed a positional change of the implants at 2 and 8 weeks of healing, and a linear association between applied force and velocity of movement (anterior implant: χ2  = 12.12, df = 3, and p = .007 and posterior implant: χ2  = 20.35, df = 3, and p < .001). Bone apposition was observed around the implants and accompanied by formation of load-bearing trabeculae and a general cortical thickening close and also distant to the implants. CONCLUSION: The present analysis confirmed that implants can migrate in bone. The applied forces seemed to stimulate bone thickening, which could explain why implants migrate without affecting stability.


Assuntos
Implantes Dentários , Animais , Remodelação Óssea , Osso e Ossos , Osseointegração , Ratos , Coluna Vertebral , Titânio , Microtomografia por Raio-X
12.
Am J Orthod Dentofacial Orthop ; 156(1): 148-156, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31256828

RESUMO

This article reports on the technical aspects of using a computer-aided design-computer-aided manufacturing (CAD-CAM) insertion guide for the placement of orthodontic mini-implants used for the purpose of providing anchorage support for maxillary molar distalization. A 10-year-old girl presented with a bilateral full-step Angle Class II molar relationship in the permanent dentition, with anterior arch-length insufficiency and blocked out maxillary canine teeth. The primary treatment objective was to provide an esthetic and functional occlusal outcome, and secondarily to avoid the removal of multiple premolar teeth. The patient was initially treated with an implant-supported distalization device, and the occlusion was subsequently detailed with preadjusted fixed orthodontic appliances. The CAD-CAM procedure facilitates the safe and precise insertion of mini-implants in the anterior palate, potentially broadening the scope of use of palatal mini-implants for less experienced clinicians. The illustrated protocol allows for the insertion of mini-implants and fitting of a prefabricated appliance in a single office appointment.


Assuntos
Parafusos Ósseos , Desenho Assistido por Computador , Implantes Dentários , Má Oclusão de Angle Classe II/terapia , Procedimentos de Ancoragem Ortodôntica/métodos , Desenho de Aparelho Ortodôntico/métodos , Técnicas de Movimentação Dentária/métodos , Dente Pré-Molar , Cefalometria/métodos , Criança , Dente Canino , Modelos Dentários , Dentição Permanente , Estética Dentária , Feminino , Humanos , Má Oclusão de Angle Classe II/diagnóstico por imagem , Má Oclusão de Angle Classe II/cirurgia , Maxila/diagnóstico por imagem , Maxila/cirurgia , Dente Molar , Procedimentos de Ancoragem Ortodôntica/instrumentação , Desenho de Aparelho Ortodôntico/instrumentação , Aparelhos Ortodônticos Fixos , Fios Ortodônticos , Palato/diagnóstico por imagem , Palato/cirurgia , Planejamento de Assistência ao Paciente , Técnicas de Movimentação Dentária/instrumentação , Resultado do Tratamento
13.
Am J Orthod Dentofacial Orthop ; 155(5): 725-732, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31053288

RESUMO

A unique clinical challenge presents when dealing with a compromised first permanent molar. A compelling treatment option for consideration is the removal of a nonrestorable first permanent molar, with the subsequent "replacement" through controlled mesial tooth movement of viable second and third molars. To reinforce the anchorage support associated with such a planned movement, indirect or direct implant-supported mechanics may be used. With the use of direct anchorage, orthodontic brackets are not required and space closure can be commenced immediately. In this article, we report the clinical procedure and design of direct-anchorage mechanics used for the successful closure of a maxillary first permanent molar space with the use of an implant-supported appliance (Mesialslider). Treatment was completed in just under 12 months, with successful mesial movement of the maxillary second and third molars without the need for the bonding of orthodontic brackets on the anterior dentition. The result was determined to be stable over a 3-year period.


Assuntos
Implantes Dentários , Dente Molar , Procedimentos de Ancoragem Ortodôntica/instrumentação , Fechamento de Espaço Ortodôntico/métodos , Técnicas de Movimentação Dentária/instrumentação , Adolescente , Cefalometria , Feminino , Humanos , Radiografia Panorâmica
15.
Clin Oral Investig ; 23(7): 3063-3071, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30413950

RESUMO

OBJECTIVES: Previous research revealed that autogenous tooth roots may be biologically equivalent to conventional bone grafts for lateral ridge augmentation. However, these analyses were limited to two dimensions, whereas healing is a volumetric process. The present study aimed at volumetrically assessing the microstructure following lateral ridge augmentation using extracted tooth roots. MATERIAL AND METHODS: The roots of differently conditioned maxillary premolars (i.e., healthy: PM-C; endodontically treated: PM-E; ligature-induced periodontitis: PM-P) and retromolar cortical autogenous bone (AB) blocks were used for lateral ridge augmentation at chronic-type defects in the lower quadrants of n = 16 foxhounds. At 12 weeks, titanium implants were inserted and left to heal for another 3 weeks. Tissue biopsies were scanned using microcomputed tomography (µCT), and volumes of interest were separated at the buccal and oral aspects to measure bone volume per tissue volume (BV/TV), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), and connectivity density (Conn.D). RESULTS: All groups investigated revealed comparable BV/TV, Tb.Th, Tb.Sp, and Conn.D values at either the augmented buccal or pristine oral aspects, respectively. A gradual but heterogeneous replacement of grafts was observed in all groups, but residual PM fragments were particularly noted in PM-C and PM-P groups. CONCLUSIONS: Differently conditioned PM and AB grafts were associated with a comparable bone microstructure within the grafted area. The duration of replacement resorption may vary considerably among the subjects. CLINICAL RELEVANCE: Autogenous tooth roots may serve as potential alternative to AB for localized alveolar ridge augmentation.


Assuntos
Aumento do Rebordo Alveolar , Raiz Dentária , Animais , Transplante Ósseo , Cães , Feminino , Masculino , Raiz Dentária/diagnóstico por imagem , Microtomografia por Raio-X
16.
Int J Implant Dent ; 4(1): 35, 2018 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-30357551

RESUMO

BACKGROUND/AIM: Retraction of the upper incisors/canines requires maximum anchorage. The aim of the present study was to analyze the efficacy of mini implants in comparison to conventional devices in patients with need for en masse retraction of the front teeth in the upper jaw. MATERIAL AND METHODS: An electronic search of PubMed, Web of Science, and EMBASE and hand searching were performed. Relevant articles were assessed, and data were extracted for statistical analysis. A random effects model, weighted mean differences (WMD), and 95% confidence intervals (CI) were computed for horizontal and vertical anchorage loss at the first molars in the analyzed patient treatments. RESULTS: A total of seven RCTs employing direct anchorage through implants in the alveolar ridge were finally considered for qualitative and quantitative analysis, and further five publications were considered for the qualitative analysis only (three studies: indirect anchorage through implant in the mid-palate, two studies: direct/indirect anchorage in the alveolar ridge). In the control groups, anchorage was achieved through transpalatal arches, headgear, Nance buttons, intrusion arches, and differential moments. WMD [95% CI, p] in anchorage loss between test and control groups amounted to - 2.79 mm [- 3.56 to - 2.03 mm, p < 0.001] in the horizontal and - 1.76 mm [- 2.56 to - 0.97, p < 0.001] favoring skeletal anchorage over control measures. The qualitative analysis revealed that minor anchorage loss can be associated with indirect anchorage, whereas anchorage gain was commonly associated with direct anchorage. Implant failures were comparable for both anchorage modalities (direct 9.9%, indirect 8.6%). CONCLUSION: Within its limitations, the meta-analysis revealed that maximum anchorage en masse retraction can be achieved by orthodontic mini implants and direct anchorage; however, the ideal implant location (palate versus alveolar ridge) and the beneficial effect of direct over indirect anchorage needs to be further evaluated.

17.
Prog Orthod ; 19(1): 42, 2018 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-30345472

RESUMO

BACKGROUND: Protraction of maxilla is usually the preferred and more commonly used treatment approach for skeletal Class III with a retrognathic maxilla. The aim of this study was the comparison of the skeletal and dental effects of two skeletally borne appliances for maxillary protraction: a) Hybrid-Hyrax in combination with facemask (FM), b) Hybrid-Hyrax in combination with Mentoplate (ME). METHODS: Thirty four Patients (17 facemask, 17 Mentoplate) were investigated by means of pre- and posttreatment cephalograms. The two groups matched with regard to treatment time, age gender and type of dentoskeletal deformity before treatment. RESULTS: Both groups showed a significant forward movement of A-point (FM GROUP: SNA + 2.23° ± 1.30°- p 0.000*; ME: 2.23° ± 1.43°- p 0.000*). B-Point showed a larger sagittal change in the FM Group (SNB 1.51° ± 1.1°- p 0.000*) compared to the ME group (SNB: - 0.30° ± 0.9°- p 0.070). The FM group showed a significant increase of the ML-NL + 1.86° ± 1.65° (p 0.000*) and NSL-ML + 1.17° ± 1.48 (p 0.006*). Upper Incisor inclination did not change significantly during treatment in both groups as well as the distance of the first upper Molar in relation to A-point. CONCLUSION: Both treatments achieve comparable rates of maxillary protraction, without dentoalveolar side effects. Skeletal anchorage with symphysial plates in the mandible provides greater vertical control and might be the treatment of choice in high angle patients.


Assuntos
Aparelhos de Tração Extrabucal , Má Oclusão de Angle Classe III/terapia , Desenho de Aparelho Ortodôntico , Técnica de Expansão Palatina/instrumentação , Cefalometria , Criança , Humanos
18.
Head Face Med ; 14(1): 16, 2018 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-30231897

RESUMO

BACKGROUND: Surgically assisted rapid maxillary expansion (SARME) is primarily used in adult orthodontics. In many cases it is followed by further surgery to address further anteroposterior and/or vertical discrepancies. Treatment times in such cases are often long with adult patients usually requesting invisible appliances. Lingual appliances can provide the mechanical control required as well as fulfil the aesthetic demands in such cases. However lingual appliances are usually custom made and indirectly bonded. Due to tooth movement following surgery there is usually a long delay before impressions can be made for customized lingual appliances. This results in a long delay before alignement and leveling can be commenced post-surgery. CASE PRESENTATIONS: Three cases are presented here demonstrating the simultaneous placement of bone anchored expansion devices for surgically assisted rapid maxillary expansion with customized lingual appliances. CONCLUSIONS: The combination of the two procedures allows the alignement and leveling to commence very soon after surgery significantly reducing treatment times. The design of the appliances and the clinical procedures are described and discussed.


Assuntos
Estética Dentária , Maxila/anormalidades , Maxila/cirurgia , Aparelhos Ortodônticos , Técnica de Expansão Palatina/instrumentação , Adulto , Prótese Ancorada no Osso , Terapia Combinada , Congressos como Assunto , Feminino , Humanos , Masculino , Maxila/diagnóstico por imagem , Pessoa de Meia-Idade , Desenho de Aparelho Ortodôntico , Braquetes Ortodônticos , Desenho de Prótese , Amostragem , Resultado do Tratamento
19.
Clin Oral Investig ; 22(2): 801-810, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28681247

RESUMO

OBJECTIVES: Treatment outcomes are frequently evaluated based on the superimposition of digital dental models. However, errors from surface matching may distort these findings. The aims of this study were (i) to develop a simulation unit to mimic point set registrations and (ii) to evaluate the impact and clinical relevance of manual landmark selection errors on registration accuracy. MATERIAL AND METHODS: Ten randomly selected dental casts were digitized using a 3D laser scanner, and were loaded by an in-house developed simulation unit (MATLAB R2014a). First, the models were digitally duplicated and one surface was rotated and translated at random. Landmark-based registration was performed with 3 to 15 landmarks, and Gaussian noise was increased iteratively from 0 to 2 mm which simulated CP selection inaccuracy. Iterative closest point (ICP) matching was performed with and without addition of Gaussian noise. Finally, root-mean-squared (RMS) errors and Hausdorff distances were calculated, and averaged for each matching algorithm and noise level. RESULTS: Selection of 10 control points provided reliable registration even in the presence of noise. ICP improved registration results, but noise above 0.5 mm clearly worsened the outcomes. CONCLUSION: Reliable superimposition of digital dental models is possible if 10 carefully selected control points with deviation below 0.5 mm are used for initial landmark-based registration. CLINICAL RELEVANCE: Potential registration errors should be considered carefully whenever superimposed digital dental models are interpreted.


Assuntos
Modelos Dentários , Processamento de Imagem Assistida por Computador/métodos , Lasers , Pontos de Referência Anatômicos , Simulação por Computador , Humanos , Aumento da Imagem/métodos , Maxila
20.
J Orofac Orthop ; 79(1): 11-18, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29134232

RESUMO

PURPOSE: To (1) quantify the three-dimensional treatment effect of a Mesialslider appliance using superimposed digital models, (2) to evaluate anchorage loss (measured by incisor displacement), and (3) to assess agreement between two different matching approaches, i.e., control point (CP)-based and iterative closest point (ICP) matching. METHODS: In a retrospective study, the effects of a skeletally anchored uni- and bilateral mesialization appliance (Mesialslider) as well as simultaneous mesialization and distalization appliance (Mesio-Distalslider) were evaluated in 48 subjects (aged 11-53 years). Pre- and posttreatment casts were digitized and superimposed with two different approaches, i.e., using ten manually selected control points located at the anterior palate and by means of an automated ICP-matching approach using a standardized palatal reference area. The treatment effects were evaluated using control points on the maxillary central incisors and maxillary molar teeth, and the methods were compared through the application of linear regression analyses and computation of alignment errors. RESULTS: Average upper molar mesialization was 6.3 ± 2.6 mm. Anchorage loss, designated as the mean amount of upper incisor displacement, was less than 0.5 mm in all dimensions investigated. Using the measurement method sufficient registration was possible using both approaches and corresponding tooth movements were significantly correlated (p < 0.01). CONCLUSIONS: Accurate measurements of tooth displacement can be performed using both CP- and ICP-based matching approaches. Within the limits of performing a retrospective study, a premolar width of molar mesialization appeared possible without clinically relevant anchorage loss.


Assuntos
Desenho Assistido por Computador , Modelos Dentários , Movimento Mesial dos Dentes , Dente Molar , Procedimentos de Ancoragem Ortodôntica/métodos , Desenho de Aparelho Ortodôntico , Técnicas de Movimentação Dentária , Adolescente , Adulto , Criança , Feminino , Humanos , Imageamento Tridimensional , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Adulto Jovem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...