Glossary

See: Orientation jig

An orientation jig is a device that is created in the laboratory. This abutment transfer device is designed to correctly maintain a component’s positional relationship as it is transferred from the custom-designed cast to the patient’s mouth. Abutment transfer devices are available for use with both closed tray and open tray techniques.

A restorative dentist uses impression coping (i.e., transfer coping) to create a cast that is identical to the patient’s mouth. This cast is used to ensure that the correct position of the patient’s abutment or implant is attained at the time that it is placed. Although impression coping is appropriate for the creation of an abutment level or an implant level cast, the correct coping must be used in each circumstance (e.g., impression posts, transfer copings, etc.).

The abutment-implant interface is the area of the abutment connection where the prosthetic screw comes into contact with the abutment. There are several different types of abutment-implant interfaces, all of which are affected by the particular type of hardware used. Types of abutment-implant interfaces include straight matching, straight non-matching, straight one-piece, concave matching, concave non-matching, and concave one-piece. For proper fit and overall success of a dental implant, the abutment-implant interface must be flush with no space or micromotion in between the prosthetic screw and the abutment. If micro motion is detected, more torque may be applied, however, periodontists must be careful to avoid applying too much force. If the abutment-implant interface is not flush, the integrity of the implant may be compromised and the patient may have a higher risk of overall implant failure. What type of hardware is used usually depends on the preferences of the periodontist.

There are two different levels of impressions that can be made in implant dentistry — abutment-level impressions and implant-level impressions. Each type of impression has benefits and caveats, and which is used depends largely on the type of procedure that the patient needs to have and what the periodontists preference is. An implant level impression requires subgingival placement of copings, while abutment-level impressions are easier due to supragingival margins. Impression copings are necessary for implant-level impressions, however, in some cases they don’t need to be used with abutment-level impressions. However, custom abutment is typically not available with abutment-level impressions, and abutment modification may be needed in the mouth. A periodontist will perform a full examination and conduct several imaging studies, including potentially 3-D volume renderings, to determine whether abutment-level impressions or implant-level impressions are necessary to achieve the doctor’s and the patient’s desired results.

An access hole in implant dentistry is an opening in the artificial tooth (crown) of a screw-retained dental implant. This opening provides access to the abutment or screw prosthesis, hence its name. Typically, the access hole is placed on the lingual or occlusal surface, but may be placed elsewhere depending on the preference of the attending surgeon. Because the access hole easily allows food and bacteria to become trapped inside the implant, it must be covered after the completion of the dental implant procedure. If this isn’t done properly, bacteria can cause the implant to become infected, which is likely to result in rejection and potentially bone loss if the underlying jawbone is affected. Many dental professionals use plumber’s tape or cotton pellets, however, plumber’s tape is often considered the better choice. It is self-adhering, so it packs down onto itself easily and forms a tight seal that protects the implant.

The principle maxillary sinus ostium (PMO) and accessory sinus ostium (i.e., accessory ostium) are the anatomical structures of the middle meatus that are referred to as the osteomeatal complex. This complex contributes to the final drainage pathway of the anterior ethmoidal, maxillary and the frontal sinuses. The principle maxillary sinus ostium is present throughout the population; however, the accessory ostium is not. The accessory ostium only occurs in 30 to 40 percent of the population.

Typically, the maxillary sinus is located close to the alveolar ridge of the first molar and second premolars; therefore, it is not uncommon to find the roots of the first and second molars in the maxillary antrum. However, when these teeth are lost, the sinus expands into the remaining alveolar bone. As time passes, the floor of the sinus becomes the crest of the remaining alveolar ridge; thus, the level of the bone and the floor of the nasal cavity may be nearly identical. In a case such as this, before dental implants can be placed, bone grafts may be necessary.

See: Ostium (maxillary sinus)

Accessory ostium, also referred to as accessory sinus ostium or just sinus ostium, are a common anatomical variation in humans. However, they may be due to a sinusal disease.They are described as bony dehiscences that are covered with mucosa that allow nasal fluids to leak into other areas of the sinus. Despite this, no connection has been found between the presence of accessory ostium and the increase in rhinitis or sinusitis symptoms in patients who have them. The cause of accessory sinus ostium may also be attributed to maxillary sinusitis, obstruction of the primary ostium, or anatomical or pathological abnormalities in the middle meatus. These conditions may cause the rupture of membranous areas, resulting in accessory ostium. Knowledge of the structures within the maxillary sinus is important in determining whether the patient will need a bone graft prior to the implant. In rare cases, implant hardware can become displaced in the sinus cavity.

This term refers to some form of biological material that is lacking intact cells, not divided into cells or devoid of cells. Consider that an acellular vaccine contains cellular material; however, the cells are not complete. In dentistry, acellular dermis is frequently used to address issues related to gingival tissue. Acellular dermis is biomaterial that is derived from animal or human tissue. This tissue is processed in such a way as to remove cells, while retaining some of the extracellular matrix (ECM). The ECM consists of a collection of extracellular molecules that are secreted by support cells. These cells provide biochemical and structural support to surrounding cells. Although the structure of an extracellular matrix depends on where the tissue originated, all ECMs consist of proteoglycans, collagen fibers and multi adhesive proteins.

Functions of the ECM include:

• Segregating tissues
• Controlling the communication that occurs between the cells
• Forming a support structure for the cells
• Regulating various cell processes (e.g., migration, growth and differentiation)

An allogeneic skin graft is derived from donated human skin. Grafts are used for a variety of soft tissue applications including gingival augmentation, visible root coverage, soft tissue ridge augmentation as well as to address soft tissue augmentation around dental implants. When a gingival graft is necessary, these grafts can be used to eliminate the need for an autograft.

Some acellular dermal allografts are processed using detergent and a sodium chloride solution, which removes the viable dermal cells as well as the epidermis while preserving the skin’s original dermal collagen matrix. By removing the cells, the likelihood of graft rejection or inflammation decreases. The tissue is disinfected with a solution consisting of detergents that have antiseptic and acidic reagents to ensure it passes the sterility standards as set forth by the United States Pharmacopeia Standard 71 (USP <71>). Once it is sterile, the tissue is freeze-dried, then cut to size and packaged using terminally sterilized materials. These acellular dermal allografts are available in a variety of sizes and thicknesses: These pieces of tissue just need to be rehydrated and they are ready to use.

An acellular dermal matrix graft is similar to the cellular dermal allograft in that they are both derived through the process of removing cells from animal or human tissues while retaining portions of the extracellular matrix (ECM). However, unlike traditional xenografts and allografts, an acellular dermal graft is usually completely devoid of cells. The main components of ADM are elastic fibers and collagen bundles.

There are a variety of acellular dermal graft products available: For example, a regenerative tissue matrix is processed in such a way as to preserve the tissue’s biologic components while maintaining the structure of the dermis itself. Acellular dermal matrix graft products differ in the processing methods used to create them as well as in their size and thickness.

Grafts can be used for numerous soft tissue applications, including:

• Soft tissue ridge augmentation
• Gingival augmentation
• Soft tissue augmentation around implants
• Exposed root coverage

If a gingival graft is required, an acellular dermal graft can be used as an alternative to an autograft.