Screw Restoration Essay

absence of retention and stability. Among implant rehabi¬litations, some authors consider overdentures the first treatment option for patients with a completely eden¬tulous mandible , .

Implant overdentures have contraindications, mainly in relative to the risks related to the surgical procedures, even if in specific cases it can be regarded as a minimally invasive one. Additionally, using this specific treatment concept is limited to cases with reduced prosthetic vertical space that makes it impossible to apply the attachment systems and also provide adequate prosthesis resistance (e.g., using Locators requires a minimum of 8.5mm vertical space and 9mm horizontal space; bar attachments require 10 to12 mm vertical space) .Implant overdentures are not recommended when there is a decreased D4 bone density, in bruxism and in severe oral hygiene deficiency.

In a study of 34 patients aged 75 years or over who depended on assistance for daily living activities, patients were randomly assigned to receive two mandibular implants to support an overdenture or a relined conventional mandibular denture. In the patients who received the mandibular implant overdenture treatment, an increased oral health-related quality of life was reported; however, chewing efficiency was no different between the groups. The insertion of the mandibular implant overdenture was noted as problematic for some patients and their caregivers due to the nature of the Locator attachments, and in two cases the attachments were replaced by attachments that permitted easier insertion . This is an important consideration for

-implant-supported overdentures have many advantages in comparison with the conventional dentures, including good stability, good retention, reduced residual ridge resorption, improved function, and esthetics. It is also possible to incorporate the existing denture into the new prosthesis. Another advantage is the easier surgical procedure and reduced number of the implants .and preservation of the residual alveolar ridge, increased comfort and chewing efficiency , greater satisfaction and an improved quality of life of the patient . In contrast to implant-supported prosthesis treatment, the implant- retained overdenture requires fewer implants, making the surgical procedure less invasive and expensive;

Mechanical load and stress distribution are directly related to the longevity of implants and to peri-implant bone loss1. In the osseointegrated dental implant, occlusal loads are transmitted directly to the surrounding bones. When overloading happens, high deformations (above 2000–3000 microstrain) occur in the bone around the implants. When pathological overloading occurs (over 4000 microstrain), stress and strain gradients exceed the physiological limits of the bone, which may cause micro-fractures at the bone–implant interface, fracture of the implant, loosening of components of the implant system, and unwanted bone resorption2. Bending moments resulting from non-axial overloading of dental implants may cause stress concentrations

Pimduen rungsiyakull et al (2011)19 studied the various occlusal designs on the strain development and its effect on simulated bone with implants supporting single crowns as models. Strain gauges were attached to the cervical area of each model. Occlusal design, magnitude and load location were tested to analyse the maximum axial strains (με) of 4 occlusal designs: 4- and 6-mm occlusal table with 30-degree cusp inclination dimensions and 4- and 6-mm occlusal table with a 10-degree cusp inclination dimensions and concluded that a reduction in occlusal table dimension and cuspal inclination effectively reduced the experimental bone strain on implants that support single crowns. Occlusal table dimensions appeared to have a relatively major role

The main disadvantage of ball-retained implant dentures was revealed in a study that followed people with ball- and bar-systems for several years. The study found that people with ball-retained implant dentures needed repairs a bit more frequently than people who had bar systems.

In this study, the retention phase was divided into four periods, and the dentists were asked to define the duration of each period in details, while using removable retainers. There were big differences in dentists' responses, because not all the dentists were following a four periods retention regimen. In addition, a high variety regarding the duration of retention phase was described, which was between 6 months and lifelong, as many dentists prefer to instruct their patients to wear the removable retainer permanently. In general, the median of the first period of retention was six months, in which the patients were asked to wear the retainer 13 hours per day, and seven days per week (Table 4.2). When fixed retainers were applied, the vast

A dental implant is an root for an artificial tooth that is typically anchored to the jaw bone, and holds the replacement tooth in place. In some situations, it is not possible to use the jawbone to anchor the tooth, causing the need to rely on gum tissue. It’s called a subperiosteal implant, and here are 4 common questions about them.

A Systemic review of survival rate of mandibular overdenture supported by two or four implants did not show any significant difference(36). Survey of 16 nationally representative academic prosthodontists in the United States showed that their first choice of treatment for edentoulus patients was the mandibular implant supported overdenture with 2 implants(37). Randomized clinical trial showed that the mandibular overdenture supported by 2 implant treatment is preferred by patients over the bar attachment treatments. This preference occurs despite greater prosthesis retention with the 4-implant bar. 52% selected the independent ball attachment, 32% the 4-implant bar, and 16% the 2-implant bar(38). Reducing the number of implants required to support an overdenture, the cost can be reduced. Studying the forces falling on implants by either finite element and strain gauge showed that two instead of four implants in the mandible can also offer an almost equal amount of stability to the denture(39). Cross section study on twenty five patient’s satisfaction level who had a complete denture supported one or two or three implants shows no statistical difference(40). Photoelastic study showed that varying the number of implants had no

Source: Soares, Ana C , and Alexandre Cavalheiro. “A Review of Amalgam and Composite Longevity of Posterior Restorations.” Revista Portuguesa de Estomatologia, Medicina Dentária e Cirurgia Maxilofacial, vol. 51, no. 3, 2010, pp. 155–164. EBSCOhost, online.

Fugazzotto conducted the only study comparing implants immediately placed into sites with periapical pathology with those immediately placed into sites without periapical pathology in the same patient, it was observed that both treatments yielded comparable results with no statistically significant difference in survival rates.(165)

Dental implants may be considered the best treatment option for patients with hypodontia. Using dental implants in patients with hypodontia may be challenging due to some limitations such as reduced mesiodistal space, impairing the ideal positioning of implants. Too often, surgeons attempting to place standard-diameter implants have forced the restorative team to manage these small dimensions with a lack of adequate prosthetics because of the size and diameter of the fixture(nazarian) All these setuation requiring the use of

Dental implants underwent numerous alterations and advancements in the design. 1 Despite this, failures at implant or prosthesis level are common; of the implant ones, loss of integration, soft tissue defects, positional failures and biomechanical failures are reported to be the major categories. 1-4 Among the biomechanical complications, screw loosening (SL) is most commonly

Implant surgery in the edentulous premaxilla is often challenging because of esthetic, phonetic and biomechanical considerations. In the maxilla, resorption following tooth extraction occurs mainly within the first 3-12 months post-operatively (1). Bone resorption following tooth loss occurs in both a lingual and apical direction, resulting in an edentulous maxilla that is narrower with a loss of vertical height. This resorption is responsible for the edge-to-edge or reverses occlusal relation of the residual crests that is often observed in patients with completely edentulous maxillae (2).