Dentures (Dental Prostheses)

Types, stages and benefits

,,A fixed denture, screw-retained on implants, requires meticulous treatment planning compared to conventional total dentures. However, the major impact this change has on the patient's quality of life and self-esteem is our fulfillment.’’ - Dr. Cristina Păcurar, dentist, Aesthetics and Prosthodontics.

In this article:

• Introduction;
• Types of fixed dentures;
• Stages of fixed dentures;
• Classic dentures vs fixed dentures;
• Advantages and disadvantages of fixed dentures;
• Maintenance.

Introduction

• Fixed prostheses offer high predictability and patient satisfaction;
• Fixed dentures offer higher patient satisfaction and quality of life compared to other treatment options;
• The available distance between anterior and posterior implants determines the cantilever length of a denture;
• The screw-retained design offers biological and maintenance advantages over cemented designs.

Fixed dentures offer both functional and aesthetic benefits and can easily be mistaken for the patient's natural dentition when compared to alternative treatment options such as full dentures or implant-removable dentures. There is significantly less bulk to a fixed denture, which is perceived to be more comfortable and, as there is no need for mucosal support, patients can chew with more force and eat a wider range of foods. 

Fixed dentures result in an increase in posterior mandibular bone tissue due to adaptation to higher chewing forces, whereas conventional dentures result in bone loss in the posterior regions. 

As a result, patients report increased social confidence, and quality of life satisfaction scores are highest in patients with a fixed implant denture. With all fixed dentures, the contour must be carefully applied to allow access for oral hygiene, as these dentures cannot be removed by the patient for cleaning. When a fixed denture is close to the oral mucosa, the surface of the denture should be smooth and highly polished.

What are dentures?

When a patient is missing all of their upper or lower teeth, they have several options to replace the remaining teeth. Some patients prefer conventional dentures that sit directly on the gum, while others prefer dental implants, i.e. dentures screwed onto these implants. Implant-screw-retained dentures are ideal for those patients who prefer comfort and increased functionality.

Classic dentures

Classic dentures are removable devices that are made to mimic missing teeth and gums. They are positioned on the remaining gum and are usually held in place by the suction created by their good fit. If the natural fit is not sufficient, adhesives may also be used. Classic dentures are a time-tested approach. However, they do eventually cause muscle and bone loss in the jaw. This changes the patient's appearance, making them look older. Unfortunately, the discomfort caused by dentures not fitting the gum is very common.

Fixed dentures

People with several or all missing teeth understand the struggle with dentures that slip while speaking or loosen while laughing. A fixed denture is a denture that eliminates the problems associated with traditional, conventional dentures. 

An overdenture is a denture supported by implants so that it remains stable and in place. It provides a natural smile that allows the patient to eat comfortably, laugh, smile without worrying about the denture moving. An overdenture can ultimately improve a person's quality of life by successfully replacing the function of natural teeth. 

Like conventional dentures, they can be removed from the prosthetic field as needed and are made of false teeth and gums, but they are fixed by implants and only the denture specialist has access to them. The patient does not have to remove them during sleep, nor during hygiene. Thus, teeth are brushed in the same way as natural teeth. 

Depending on the clinical case, the specialist determines the number of implants required. 

''All-on-4® '' is the treatment concept that has paved the way for edentulous ridge treatments ever since it pioneered the field almost 20 years ago. 

Studies have scientifically proven that the All-on-4® system is considered the best option available on the market, rehabilitating the entire oral cavity on a reduced number of implants. The All-on-4® concept is a minimally invasive solution for fixed prosthodontic rehabilitation with a reduced healing time and a 98% success rate after 7.5 years, according to studies. 

By achieving a new smile in a single day, as well as exceptional aesthetic results, this concept maximizes patient satisfaction.

Why All-on-4® treatment? Only 4 implants, but with countless benefits!

,,The All-on-4® technology comes as a solution to an important challenge, that of orally rehabilitating edentulous people and particularly those without teeth and bone. The success is huge just imagining what it is like to tell a patient, who has been offered dentures as an alternative for life, that you can give them false teeth in about a day and that we can do it without bone addition and with a much higher success rate than with bone grafting’’, says Dr. Cristian Csapo Martinescu, dental aesthetics and implant dentist at DENT ESTET.

The All-on-4® system offers patients an immediate improvement in function, aesthetics and phonetics.

• Shorter treatment time and lower cost compared to other conventional implant treatment modalities;
• A favorable bone level for axial and angled implants;
• Higher survival rate: 98% after 7.5 years according to studies;
• Provides maximization of anterior/posterior space while avoiding important anatomical structures;
• Helps avoid complex and unreliable grafting procedures, increasing the acceptance rate of the dental implant by the body;
• Very high stability with only 4 implants. 

The All-on-4® treatment concept allows us to offer hope to many patients who until now did not have many encouraging options. Now we can considerably change their lives for the better. 

And because this treatment is more accessible to patients, a huge number of people become candidates for implant insertion. For us, the All-on-4® treatment concept has created a new market. 

We recommend dentists to learn this concept with an open mind! There are practically millions of patients who can benefit from this treatment. Nobel Biocare has a predictable workflow with a great support system that guarantees your success. 

Several types of implant-supported final prosthetic work (the All-on-4® system) are available; the advantage is that patients, together with their clinician, can choose the option that best suits their needs.

Fixed dentures on implants have the following benefits:

• Comfort - fixed dentures on implants stay in place and will be comfortable;
• Confidence - the patient does not have to worry about the denture moving;
• Health - dentures on implants allow the patient to eat normally. Patients can continue to eat healthy and varied food without worrying about chewing difficulties;
• Appearance - these devices prevent bone and muscle loss, so the patient's physiognomy will not change;
• Easy to maintain - their hygienization is similar to that of natural teeth, performed daily, regular check-ups and X-rays at the specialist;
• Reliability - they are durable and long-lasting.

Types of fixed prostheses

Fixed dentures on implants can be fixed or removable depending on the clinical case and the patient's needs. Both types are significantly more comfortable and aesthetic than a conventional denture and help improve a person's oral health by preventing further bone loss and supporting nutritional needs.

Metal-acrylic fixed dentures

This type of denture has excellent long-term clinical results and until recently was the main type of fixed implant denture offered to patients. It is made with a metal frame that attaches to implants and has been designed to incorporate mechanical elements to help retain acrylic resin and artificial teeth. Current technology also uses CAD/CAM to fabricate precision frameworks. The final prosthesis is usually screw-retained and is relatively easy to retrieve if the teeth or acrylic resin need to be repaired.

Metal-ceramic fixed dentures

This prosthesis simulates a typical metal-ceramic bridge made for natural teeth, in that a substructure is fabricated to provide both attachment to the underlying implants and an ideal thickness on the ceramic for long-term durability. It is waxed-up with the full contour of the framework, then cut to create the ideal thickness of veneering ceramic and then scanned. The scanned image is used in a CAM process to create a metal frame from a compatible ceramic alloy. In some situations, the wax-up can be molded into a metalceramic alloy, but the accuracy of the full spring match is more difficult to achieve than a CAM substructure. A metal-ceramic prosthesis has very good aesthetics because the ceramic is more lifelike than acrylic resin. A disadvantage of a metal-ceramic denture is that chipping or ceramic fractures can occur which can be difficult to repair. The opposite occlusion should invariably and conscientiously be considered, especially if a parafunctional habit is suspected. If appropriate, consideration may be given to the design of an occlusal guard for additional protection of applied dental materials.

All-ceramic fixed dentures

This type of denture is conceptually similar to the metal-ceramic denture, except that the substructure is made of zirconia instead of metal. The veneer ceramic is then applied to the zirconia. Patients who require a metal-free denture and/or demand an excellent aesthetic result may be better managed with an all-ceramic denture in which the gray color of the metal does not need to be masked. Again, chipping or fracturing of the ceramic can be difficult to repair and occlusal considerations, especially parafunctional ones, must be carefully considered.

Fixed implant-screw-retained versus implant-cemented dentures

Both types of denture retention can give excellent long-term results, although the retrievability offered by screw-retained dentures clearly offers the safer and more versatile option. However, some dentists prefer the cementation protocol, as this approach excludes the visibility of access holes in the occlusal or vestibular surfaces of the artificial teeth. However, it should be emphasized that any submucous extension of a prosthesis could predispose to iatrogenic peri-implant inflammation with concomitant marginal bone loss if all cement debris is not removed. A screw-retained design is recommended for full-arch prostheses because any subsequent maintenance or treatment procedure can be performed more efficiently by removing the prosthesis; for example, in the case of technical problems such as fracture of the facing material, screwbolts, or treatment of mucositis and peri-implantitis. The problem in the area of screw access paths, to be located in aesthetically relevant areas, can be solved by the use of angled bridges (i.e. multi-unit bridges) or angled screw channels.

Aesthetic and phonetic considerations

The aesthetic requirements of the patient should be discussed very carefully before treatment, particularly when a maxillary fixed bridge is planned in a patient wearing dentures. A duplicate denture should be attempted, and this helps to reveal the lip support provided by the teeth alone. 

In addition, speech can be a challenge for those wearing maxillary fixed dentures. In particular, the S sound is the most mispronounced speech sound. It is a fricative consonant that is created by altering the airflow on the path from the lungs through the vocal tract. The airflow must be undisturbed in the anterior palatal area, flowing over the palatal concavity of the anterior teeth and passing between the incisal edges of the upper and lower anterior teeth. The original paragraph positions of the teeth should be reproduced as accurately as possible, since any change in their inclination would result in a distortion of the S sound.

Stages of fixed dentures

The dentist will review all the steps of the implant insertion and fixed denture fabrication process. As with the insertion of a single implant, a fixed prosthesis initially has the same steps leading up to the prosthetic stage.

1. Consultation

   The doctor should be familiar with all the patient's needs and concerns, and will perform a detailed examination and review the patient's medical and dental history. Typically, digital photographs, initial impressions, and digital radiographs (OPG, CT) are taken to determine the size of the bone and whether additional surgery, such as bone grafting, is needed.

2. Implant placement

   The specialist will use a local anesthetic to numb the areas targeted for implant insertion. For anxious patients, conscious sedation assisted by an ITA specialist is recommended.

3. The healing process

   The healing time requires about 4 months before the implants can be loaded with the final prosthetic work. Throughout this healing time, the patient will wear a temporary fixed denture using a soft material, usually acrylic.

4. Taking the impression

   Scanning or traditional impression helps the specialist fabricate the final work. This will then be sent to the laboratory to make the denture framework and the artificial teeth - the aesthetic part.

5. Insertion

   Once the fixed denture is crafted, the doctor will try in the work and make any necessary adjustments. If it does not need any modifications, it will be permanently fixed with screws to the implants inserted 4 months ago. At the end, the patient will receive instructions for the proper care of the denture, and it is also recommended that the patient comes in every 6 months for regular check-ups and sanitization.

Classic dentures vs fixed dentures

A classic denture and a fixed denture are two very different types of dentures. Their only common denominator is that they replace missing teeth. 

Standard dentures are removable, affordable and quick solutions to replace missing teeth. Acrylic dentures help to restore function and aesthetics and are used when people want to eat something else. A full denture will fit over the bone crest, but may loosen over time due to bone deterioration. 

Over time, a toothless lower jaw experiences bone resorption. This causes a denture wearer to experience a loose denture that needs frequent relining and repair. When we choose to place implants, they keep the dentures stable and improve patient satisfaction. 

Fixed dentures are usually permanent and not easily dislodged. They are stable and offer much more confidence and control than standard dentures. Fixed dentures are an excellent lifelong investment in your oral and general health. 

Unlike traditional dentures, a fixed denture helps to retain and strengthen the jawbone. It also contributes to a more youthful appearance than a conventional denture and encourages bone regeneration rather than bone deterioration.

Advantages of fixed dentures

The advantages of fixed dentures are endless. Many patients opt for a conventional denture as a first choice because they are unaware of the advantages of fixed dentures.

The most common benefits include:

• A permanent solution to missing teeth;
• More confidence in chewing function, smiling and laughing;
• Retains jaw bone and provides a youthful appearance;
• No risk of dislocation as with conventional dentures;
• Restores a more natural appearance;
• Oral hygiene is greatly improved.

Maintenance

Patients immediately notice how incredibly stable and natural fixed dentures are. The work is sanitized daily at home. The patient is also advised to have regular check-ups and professional scaling every 6 months.