A 3-D finite element study of the influence of crown-implant ratio on stress distribution

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Root-supported overdentures associated with temporary immediate prostheses: a case-report

Complete denture fabrication can be a treatment challenge for many dentists, especially when the patient has remaining teeth. So, planning for use of clinical alternatives to improve the treatment prognosis and to enable greater comfort to patient must be considered. This case report describes the use of remaining roots to aid in the stability, support and retention of root-supported overdentures. Thus, immediate prostheses were planned for temporary rehabilitation prior to definitive overdentures. The aim of this study was to demonstrate the planning of root-supported overdentures attached with a ball system for retention associated with immediate dentures between the periods of preparation to fabrication of the definitive overdentures. The proposed treatment met the patient's needs such as being able to carry on normal activities during the sequencing of procedures to be performed over a period of time. The treatment had longevity with patient's knowledge about the necessity of oral hygiene and periodic controls.

Management of accidental swallowing in implant dentistry

This report describes a protocol for managing the accidental swallowing of dental instruments in implant dentistry, illustrated by a patient who accidentally swallowed a hexagonal wrench. The first step was to refer the patient to the medical emergency hospital service for radiographic and clinical evaluation. The hexagonal wrench was located in the stomach and was immediately removed with an endoscopic procedure. The gastric mucosa was sampled via biopsy and the sample submitted to the urease test, which was positive for Helicobacter pylori. Triple treatment was instituted for gastritis caused by H pylori to avoid exposing the patient to unnecessary risk. Removal of a foreign body by means of an endoscopic procedure constitutes a safe and effective treatment.

Stress distribution in bone simulation model with pre-angled implants

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Posterior partially edentulous jaws, planning a rehabilitation with dental implants

To discuss important characteristics of the use of dental implants in posterior quadrants and the rehabilitation planning. An electronic search of English articles was conducted on MEDLINE (PubMed) from 1990 up to the period of March 2014. The key terms were dental implants and posterior jaws, dental implants/treatment planning and posterior maxilla, and dental implants/treatment planning and posterior mandible. No exclusion criteria were used for the initial search. Clinical trials, randomized and non randomized studies, classical and comparative studies, multicenter studies, in vitro and in vivo studies, case reports, longitudinal studies and reviews of the literature were included in this review. One hundred and fifty-two articles met the inclusion criteria of treatment planning of dental implants in posterior jaw and were read in their entirety. The selected articles were categorized with respect to their context on space for restoration, anatomic considerations (bone quantity and density), radiographic techniques, implant selection (number, position, diameter and surface), tilted and pterygoid implants, short implants, occlusal considerations, and success rates of implants placed in the posterior region. The results derived from the review process were described under several different topic headings to give readers a clear overview of the literature. In general, it was observed that the use of dental implants in posterior region requires a careful treatment plan. It is important that the practitioner has knowledge about the theme to evaluate the treatment parameters. The use of implants to restore the posterior arch presents many challenges and requires a detailed treatment planning.

Analysis of the biomechanical behavior of short implants: the photo-elasticity method

The aim of this study was to analyze the stress distribution of short implants supporting single unit or splinted crowns by the photo-elasticity method. Four photo-elastic models were produced: A (3.75×7mm); B (3.75×7mm, 3.75×7mm and 3.75×7mm); C (3.75×10mm, 3.75×7mm and 3.75×7mm); D (3.75×13mm, 3.75×7mm and 3.75×7mm). The prostheses were made with Ni-Cr alloy. A load of 100N in the axial and oblique directions was applied, totaling 380 applications, individually capturing their images in each model. The data were randomized and analyzed qualitatively and quantitatively by 2 examiners. The oblique loading was significantly more damaging. The increase in length was favorable for stress distribution (p<0.05). The splinting was beneficial for the transmission of stresses mainly (p<0.05). The splinting of the crowns, as well as increasing the length of the first implant and axial loading was most beneficial in the stress distribution. Short splinted implants behaved better than single unit implants. Increasing of the length of the first implant significantly improved the stress distribution in all analyzed situations.

Abutment coating with diamond-like-carbon films to reduce implant-abutment bacterial leakage

Backgroud: The influence of diamond-like-carbon (DLC) films on bacterial leakage through the interface between abutments and dental implants of external hexagon (EH) and internal hexagon (IH) was evaluated. Film deposition was performed by PECVD (Plasma Enhanced Chemical Vapor Deposition). Sets of implants and abutments (N=180, n=30) were divided according to the connection design and the treatment of the abutment base: (1) no treatment (control); (2) DLC film deposition, and (3) Ag-DLC film deposition. Under sterile conditions, 1 µL of Enterococcus faecalis was inoculated inside the implants, and abutments were tightened. The sets were tested for immediate external contamination, suspended in test tubes containing sterile culture broth, and followed-up for five days. Turbidity of the broth indicated bacterial leakage. At the end of the period, the abutments were removed and the internal content of the implants was collected with paper points and plated in Petri dishes. They were incubated for 24 h for bacterial viability assessment and colony-forming unit (CFU) counting. Bacterial leakage was analyzed by Chi-square and Fisher exact tests (α=5%). The percentage of bacterial leakage was 16.09% for EH implants and 80.71% for IH implants (P<0.0001). The bacterial load was higher inside these implants (P=0.000). The type of implant significantly influenced the results (P=0.000), whereas the films did not (P=0.487). We concluded that: (1) IH implants showed a higher frequency of bacterial leakage and (2) the DLC and Ag-DLC films did not significantly reduce the frequency of bacterial leakage and bacteria load inside the implants.

Segmental osteotomy for the correction of a malpositioned single implant: an 8-year follow-up

This case report is an 8-year follow-up of a malpositioned single implant, which was treated with segmental osteotomy, to confirm the treatment's characteristics, indications, and advantages. Deep buccal positioning of an endosseous implant placed in the maxillary left central incisor area did not permit acceptable prosthetic rehabilitation, despite its favorable bone insertion with no significant marginal bone loss. The surgical procedure included osteotomy and block movement performed toward the lingual and cervical position, fixed with a provisional prosthesis and miniplates and mini-implants. A connective tissue graft was necessary for esthetics optimization and was performed in a second stage. Advantages including the prevention of alveolar ridge damage, the improvement of gingival contour, and the use of an already integrated implant are presented. Clinically satisfactory hard and soft tissue stability permitted us to consider segmental surgery as a reliable alternative for malpositioned osseointegrated implants.

Histologic and histometric evaluation of calvarial autogenous bone graft in reconstruction of atrophyc maxilla for dental implants

The calvarial bone is highlighted as a good donor area for large reconstructions of atrophic jaw for subsequent rehabilitation with implant-supported prosthesis. The aim of this study was to observe and measure through histological and histometric evaluation, the cellular events that occur at the interface of union from onlay parietal bone graft on the maxilla of 10 patients, after a period of 6 months of incorporation. The biopsies were performed at the time of installation of osseointegrated implants. The bone contact area represented 78.75% and connective contact 21.25%. The region of connective union between the bone graft to the maxillae presented new bone formation (41.26%), marrow bone (36.06%), osteoid tissue (15.86%) and connective tissue (6.80%). All samples had good graft incorporation to the receptor bed with osteogenic activity and absence of inflammatory cells.

A utilização de abutment de zircônia na reabilitação oral: aspectos protéticos e periodontais

Zirconia abutments are used to obtain satisfactory aesthetic results in implant fixed anterior prostheses when metal abutments promote a grayish mucosal discoloration of the peri-implant soft tissues. However, there is a lack of studies to confirm the clinical performance of the peri-implant soft tissues surrouding zirconia abutments. This study described a case report of a patient treated with implant fixed all-ceramic crown made out on zirconia abutment after 3 years of followup. A 47-year-old female patient was admitted to the dental clinic (Aracatuba Dental School) complaining about the fracture of her implant fixed single crown in the region of the left lateral incisor. The patient chose the replacement of the fractured prosthesis for an allceramic crown. After 3 years of follow-up it was observed that maintenance of the aesthetic results and the peri-implant soft tissue without any inflammation or gingival recessions. Within the limitations of a case report, it can be conclude that zirconia abutments is a effective rehabilitation treatment because it preserves the aesthetics and function through the maintenance of peri-implant tissues.

Effect of smoking on the survival of dental implants

Background. Although the long-term success of implant treatment has been well- established, failures can still occur and the smoking habit has been reported as a risk factor for implant loss. A literature review on the effects of smoking on the survival of dental implants was undertaken. Methods and Results. Medline database was used to carry out the review with the keywords “osseointegration”, “smoking” and “bone healing”. The cigarette has more than 4,000 bioactive chemical components with potential toxic effects to human tissues including bone. Nicotine is the main component of the cigarette and it is frequently associated with bone healing failures. Since smoking negatively affects the osseointegration of dental implants, the main target is to quit the consumption of cigarettes. Conclusion. Nevertheless, the smoking habit should not be an absolute contraindication for implant treatment, but, patients should be advised that they are at a greater risk of implant failure.

Resolução estética associando prótese sobre implante e prótese convencional na região anterior

The combination of several methods for solving aesthetics in a clinical case can be a complicating factor. The diagnosis and planning of the event held in conjunction with the dental technician expand the possibilities of success. The present case illustrates the aesthetic resolution through the association of implant- and tooth-supported prostheses using metal free ceramic systems. A 38-year old male patient presented with a complex smile. After diagnosis and treatment planning, two ceramic crowns were made, one on tooth 11 and one on the implant region 21, along with a laminated porcelain veneer on the region of 12. Aesthetic needs of the patient are predictable only with a sound diagnosis.

Osseointegration of anodized implant: effect of fibrin adhesive/TEA on primary stability

Processo FAPESP: 2012/24545-3

Influência da angulação do implante e tipo de intermediário na distribuição das tensões

The aim of this study was to evaluate the influence of implant angulation and abutment type (UCLA and Estheticone) on stress distribution in screw-retained implant-supported prostheses through photoelasticity. Three models were fabricated with photoelastic resin PL-2 (Vishay, Micro-Measurements Group, Inc Raleigh, N.C., USA) containing one external hexagon implant with 3.75x10mm (Master screw, Conexão Sistemas de Prótese Ltda., Arujá, São Paulo) with 0°, 17° and 30° degrees and a screw-retained prostheses with UCLA and Estheticone abutments. The assembly was positioned in a circular polariscope; axial and oblique (45° degrees) loads of 100N were applied in fixed points on the occlusal crown surfaces by a universal testing machine. The stress generated was photographed and analyzed qualitatively with appropriate software (Adobe Photoshop®). The results demonstrated the same number of fringes for both abutment types for each angulation, with fringes increasing in the same way. A higher number of fringes were closer in the oblique loading mode. It was concluded that there was no significant difference in stress distribution in prostheses with UCLA and Estheticone abutments. Higher stress concentrations were observed with increased implant angulation. Stress concentration and intensity were higher in the oblique load than in axial load application.

O impacto das próteses implantosuportadas na harmonia facial

Many patients seeking dental care wish to improve facial and smile aesthetics to be accepted in modern day society. In denture wearers, the physiological resorption causes atrophy mainly in the maxilla, being necessary to carry out reconstruction techniques and sometimes orthognathic surgery to improve occlusal stability and facial harmony. The aim of this study is to discuss the features related to the rehabilitation of edentulous patients with indication for reconstruction of the maxilla using bone grafts and orthognathic surgery by means of a clinical case. In the present case, after the prosthetic rehabilitation, the patient was full satisfied with obtained results and dismissed the initially proposed surgical protocol. Therefore, professionals should provide therapeutic options but the patient’s opinion should prevail provided its clinical feasibility.