Dental Technology
WHEN TO RECOMMEND IMPLANT OVERDENTURES
For patients with significant bone loss, an overdenture will restore vertical dimensions and may be the most suitable choice.
The All-on-Four treatment concept was designed to help edentulous patients and those who are facing complete tooth loss. It is extremely popular, as patients can receive an immediately loaded, full-arch restoration using just four dental implants.
The All-on-Four treatment concept was designed to help edentulous patients and those who are facing complete tooth loss. It is extremely popular, as patients can receive an immediately loaded, full-arch restoration using just four dental implants. Using fewer implants brings the cost of the procedure within reach for many people who could not afford the more traditional implant treatment. All-on-four maximizes the use of available bone, eliminating the need for bone augmentation, which may be an unsuitable or undesirable prospect for some patients.
Potential Emotional Benefits for Patients Choosing All-on-Four
Often people with complete dentures suffer discomfort when the denture rubs on the gums, especially where denture retention is compromised. Denture adhesives only offer a temporary solution, and many patients in this position actively avoid social situations due to esthetic concerns and worries that their denture may become loose at inopportune moments. Rehabilitation using implant-supported restorations can enhance the patient’s sense of well-being and quality of life.
A Faster and More Comfortable Treatment Solution
Clinicians may recommend this treatment for patients with severe atrophy of the mandible or maxilla. Traditional implant treatment generally requires bone augmentation procedures, which includes multiple surgeries and lengthy treatment times. While traditional implant treatment is effective, it means that the patient is faced with periods of edentulism, a situation that most people, understandably, fear. With All-on-Four, the implants are precisely positioned, and angling two of them allows patients to benefit from rehabilitation with just one surgical procedure. Because only four implants are generally required, healing is smoother, faster, and more comfortable for the patient.
The Basic Concept of All-on-Four
One requirement for immediate loading is that the patient must have adequate bone quality so that sufficient stability can be achieved. This treatment also relies on good drill protocol and an adequate implant design and implant surface. The patient often receives the surgery and the prosthetic restoration on the same day. Two implants are inserted vertically, usually in the lateral incisor region, while two dorsally tilted implants are inserted in the second premolar region.
Tilting the posterior implants enhances bone-to-implant contact, optimizing the bone support, even if only the minimum bone volume is available. Tilting the dorsal implants in the jawbone also enables improved anchorage by utilizing higher quality anterior bone. Another important reason for tilting these implants is to avoid vital structures while allowing for better distribution of the implants along the alveolar ridge. This, in turn, helps to optimize load distribution, allowing a restoration of up to 12 teeth to be placed. Placement of the dorsal implants can be limited by the mental foramen in the mandible and by the maxillary sinuses in the maxilla. If the maxilla is severely resorbed then it may be necessary to place zygomatic implants.
Afterward, the patient receives a provisional, pre-manufactured prosthesis that is fitted almost immediately. If the patient’s removable denture is in reasonable condition, it might be possible to use it to fabricate an immediate acrylic bridge. Stitches can be removed one week after treatment, and generally a healing period of approximately three months is necessary before the final prosthesis is fabricated. The final prosthesis is made using a new impression of the patient’s mouth. Final restoration solutions include both fixed and removable prostheses, depending on the patient’s preference and clinical needs. Fixed solutions include an implant bridge or an implant-retained overdenture. Often these permanent restorations will be made using advanced CADCAM technology for a precise fit. Each restoration is custom-designed, providing the patient with optimal esthetics.
Selecting the Most Suitable Prosthesis
One option for the permanent prosthesis is to choose a full arch bridge made from monolithic zirconia. The bridge is fabricated from 100% solid zirconia and offers the patient a durable prosthesis while maintaining good esthetics and functionality. A solid zirconia bridge is fabricated to exhibit excellent translucency and lifelike esthetics with teeth that closely resemble natural dentition. When necessary, technicians can use advanced staining techniques to differentiate gingival areas in shades that blend in with the patient’s soft tissue. Alternatively, gingiva-colored porcelain can be layered to create the most natural effect. This prosthesis is precision-made, hypoallergenic, and will not stain.
One of the most straightforward options is an implant overdenture. Sometimes the patient may prefer a removable prosthesis, because it is easy to clean where oral hygiene is a concern. When a bar design is used, the overdenture is snapped over the bar, and, although it may be able to rotate slightly, it provides good stability for the patient.
Choosing Conventional or Guided Surgery
All-on-Four treatment can be provided using conventional or guided surgery. Conventional surgery uses a flap procedure, and treatment is traditionally planned. Implants are placed using a standardized guide that helps to optimize the positioning of the implants. A provisional prosthesis can be created based on an impression taken right after surgery is completed.
In contrast, guided surgery uses 3-D diagnostics and digital treatment planning. Surgery is performed using a custom-designed surgical template. Guided surgery is suitable for minimally invasive flapless techniques. Surgical access can also be obtained through full flaps or mini flaps. Using 3-D radiological data and virtual models of bone allows the clinician to evaluate the quality and quantity of the bone and pinpoint vital anatomical structures, including the maxillary sinus and the alveolar nerve, to optimally position the dorsal implants. After the case is planned, a custom-designed surgical template can be used during surgery. At this stage, a provisional prosthesis may also be fabricated for placement soon after surgery.
Conventional and guided surgeries are suitable for patients who do not have severe parafunctions and where the maxilla has a minimum bone width of 5 mm and bone height of 10 mm from canine to canine. When restoring the edentulous mandible, bone width should be a minimum of 5 mm, while bone height should be a minimum of 8 mm between the mental foramina. The dorsal implants are tilted to a maximum of 45°, and if the angulation is 30° or more, it is necessary to splint the dorsal implants.
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