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.

Changes in the edentulous maxilla with ball and telescopic attachments of implant-retained mandibular overdentures: a 4-year retrospective study.

OBJECTIVE: This retrospective study investigated the clinical and radiographic changes in the edentulous maxilla in patients with either ball or telescopic attachments of implantretained mandibular overdentures. METHOD AND MATERIALS: Thirty-two completely edentulous patients (21 males and 11 females) received two implants in the canine region of the mandible. New maxillary complete dentures and mandibular overdentures were fabricated. Overdentures were connected to the implants either with ball (group 1, n = 16) or telescopic (group 2, n = 16) attachments. Retention and stability of the maxillary denture as well as mucosal changes of the maxillary ridge were recorded after 4 years of denturewearing. Traced rotational tomograms were used for measurements of maxillary alveolar bone loss. The proportional value between bone areas and areas of reference not subject to resorption was expressed as a ratio (R). Change in R immediately before (T0) and after 4 years (T4) of overdenture insertion was calculated for the anterior and posterior regions of the maxilla. RESULTS: After 4 years of denture-wearing, maxillary denture retention was significantly higher in group 1 than in group 2, while occurrence of flabby ridges was significantly higher in group 2 than in group 1. The change in R of the anterior region of the maxilla was significantly higher than the change in the posterior region in both groups. Group 2 showed significant anterior residual ridge resorption compared to group 1. CONCLUSION: Telescopic attachments for implant-retained mandibular overdentures are associated with increased maxillary ridge resorption and flabbiness, and decreased maxillary denture retention when compared to ball attachments.

Importancia del articulador semiajustable en la rehabilitación / Importance of the semiadjustable articulator in rehabilitation

Se realiza un estudio sobre la importancia del articulador semiajustable en la rehabilitación protésica. Se define la oclusión dentaria como la relación que se establece entre las arcadas dentarias cuando estas toman contacto entre sí permaneciendo el arco inferior inmóvil con respecto al superior. Debido a que es fundamental en la rehabilitación protésica tratar de respetar la integridad funcional del paciente, nos proponemos como objetivo reestablecer los contactos en los deslizamientos durante los movimientos mandibulares una vez rehabilitado el paciente a su pauta masticatoria. El universo estuvo constituido por 8 pacientes, entre 18 y 34 años que presentaban restauraciones en primeros y segundos premolares en mal estado. Se rehabilitaron con restauraciones extra coronales utilizando el articulador semiajustable. Una vez concluida la rehabilitación solamente se realizaron ajustes oclusales al 25 por ciento de los casos, mientras que el 75 por ciento no requirió ajuste oclusal alguno. Esto demuestra la exactitud de la técnica empleada y la efectividad del articulador semiajustable para dicha rehabilitación(AU)

A study on the importance of the semiadjustable articulator in the prosthetic rehabilitation was conducted. Dental oclussion was defined as the relation established between the tooth arches when they get in contact and the lower arch remains inmobile in relation to the upper. Due to the fact that in the prosthetic rehabilitation it is fundamental to try to respect the functional integrity of the patient, we propose ourselves as an objective to reestbalish the contact in the slidings during the mandibular movements once the patient is rehabilitated to his masticatory pattern. The universe consisted of 8 patients aged 18-34 that presented restorations of the first and second premolars in bad state. They were rehabilitated with extracoronal restorations by using the semiadjustable articulator. On concluding the rehabilitation, oclussal adjustments were made in only 25 percent of the cases, whereas no oclussal adjustment was necessary in 75 percent. This proves the accuracy of the technique used and the effectiveness of the semiadjustaable articulator for such a rehabilitation(AU)

Análise comparativa da capacidade retentiva de grampos tipo T usados em prótese parcial removível em armaçöes de titânio e cobalto-cromo / Comparative analysis of retentive capacity of clasps type T used in removable partial prosthesis in frames made in titanium and cobalt-chromium metallic alloys

Estudou-se a capacidade retentiva de grampos tipo "T" em prótese parcial removível (PPR) comparando-se armaçöes confeccionadas em liga de Co-Cr e Ti. Foram utilizados dez corpos de prova com cada tipo de liga que foram levados a um dispositivo desenvolvido para simular a inserçäo e remoçäo de armaçöes de PPR, como acontece clinicamente em pacientes, por períodos de 6 meses, 1, 2, 3, 4 e 5 anos. Depois de cada período de simulaçäo, estes corpos de prova eram levados a uma máquina de traçäo para se medir a quantidade de retençäo ainda presente em cada armaçäo, respectivamente em ambiente seco e umedecido com saliva artificial; depois disso, eram pesados em uma balança de precisäo para se observar prováveis perdas de peso, tanto das armaçöes quanto dos dentes naturais dos corpos de prova. A análise estatística dos resultados nos permitiu concluir que näo houve diferença estatisticamente significante de retençäo entre as armaçöes confeccionadas em Ti e Co-Cr, nos períodos de tempo simulados, tanto em ambiente seco quanto em umedecido com saliva artificial, e que foi estatisticamente significante a perda de peso tanto das armaçöes quanto dos dentes naturais dos corpos de prova da utilizaçäo do Ti e do Co-Cr nos referidos tempos

Intrusion of teeth in the combination implant-to-natural-tooth fixed partial denture: a review of the theories.

This article reviews the literature dealing with the combination implant-to-natural-tooth-supported fixed partial denture. The restoration of masticatory function with a combination implant-to-natural-tooth fixed partial denture is associated with a variety of undesirable clinical sequelae, including the breakage of implant components, damage to the abutment teeth, or intrusion of the abutment teeth. Theories regarding intrusion of abutment teeth combined with implants for fixed partial dentures are only speculative. Several theories are presented to explain the intrusion of natural teeth in association with implant-to-natural-tooth fixed partial dentures. One of the first theories was based on the idea that a lack of normal stimulation of the periodontal ligament produces atrophy of the periodontal ligament and intrusion of the tooth. The remaining theories relate to excessive forces being placed on the natural tooth, resulting in movement of the tooth to a less stressful position. These forces are placed on the tooth by differential energy dissipation, mandibular flexion and torsion, flexion of the fixed partial denture framework, impaired rebound memory, debris impaction or microjamming, or ratchet effect related to the use of precision attachments. Based a review of the literature, a philosophy for treating combination implant-to-natural-tooth restorations is presented.

A survey of natural tooth abutment intrusion with implant-connected fixed partial dentures.

To elicit information about the phenomenon of intrusion of natural tooth abutments in implant-connected prostheses, a survey was distributed to clinicians with varied experience. Although practitioners with more experience in fabricating implant-supported dentures connected to natural teeth reported fewer instances of intrusion, it cannot be concluded that this observation is significant. The cause of intrusion is probably multifactorial, and respondents suggested several possible causative factors: disuse atrophy, debris impaction, impaired rebound memory, and mechanical binding. Because apical migration of abutment teeth affects occlusion and oral hygiene, the authors make several recommendations for treatment planning for patients who have natural dentition adjacent to proposed implant sites.

Precision attachment retained removable partial dentures: 1. Technical long-term study.

Patients provided with 53 distal extension-base removable partial dentures retained using rigid intracoronal slide attachments were followed up to 25 years. The initial treatment consisted of fixed partial dentures involving all remaining teeth in the treated arches and removable partial dentures having a cast cobalt-chromium framework. The removable dentures showed few complications and little need for relining. The failures primarily involved the fixed partial dentures. Seven arches required complete dentures as a result of technical complications in five patients. Cement failures, root fractures, and fractures of the fixed prostheses were most problematic. The survival rate was about 65% up to 15 years, and a survival time of 50% was extrapolated to 20 years.

[Magnets used in dentistry. Preliminary data on in vitro biocompatibility]. / Magneti utilizzati in odontoiatria. Dati preliminari di biocompatibilità "in vitro".

The biocompatibility of various magnetic materials used in dentistry to secure prostheses was assessed. In vitro cell cultures were performed on coated and uncoated covered and uncovered rare earth magnets. These studies were completed by essays of the lactic dehydrogenase used as an indicator of membrane damage. The various analyses indicate that the magnets in common clinical use are not significantly cytotoxic.

[Caries in supporting teeth with and without crowns]. / Karies an überkronten und nichtüberkronten Halte- und Stützzähnen.

On the basis of 1718 teeth in 212 patients fitted with removable partial dentures, it was established that the frequency of caries in uncontrolled noncrowned abutment teeth for partial dentures was twice as high and the number of extractions three times as high as in the control group. The special risk for abutment teeth was effectively reduced by using artificial crowns. The concept of crowning abutment teeth is discussed.