Abutment screw

The dental abutment screw is the device that is used to secure the abutment to the implant. This fastener is threaded and is typically tightened until it reaches its final seating position. There are mechanical or electronic torque measuring devices that will indicate the magnitude of the torque that is being applied to the abutment screw. If proper tightening of the dental abutment screw is overlooked, serious challenges may arise.

One of the most common complications associated with dental implants is the unwanted rotation of the abutment screw. In addition, improperly using the abutment screw can result in deleterious effects on the bone, components of the implant itself and the final restoration result.

Dental abutment screws are available in various sizes, shapes and materials. It is imperative that the dentist performing the implant procedure be knowledgeable in the materials as well as the physical and mechanical aspects necessary to ensure a proper connection between the implant and the abutment.

Abutment selection

This refers to the step of the dental implant process in which the type of abutment that will serve the patient best is decided upon. Several factors are taken into consideration when choosing an abutment, some of which include the height of the soft tissue, the angulation of the dental implant, the planned prosthesis, interarch space, occlusal factors (e.g., antagonist teeth and parafunctional activities), phonetic considerations and esthetics. In addition, some patients will require two surgical sessions to complete their dental implant restoration. During the first surgery, these patients receive healing abutments. The healing abutments remain intact until the gum has healed around the dental implant. Once healing is complete, the final abutments and permanent prosthesis can be placed.

Types of abutments include:

  • Anatomic healing abutments
  • Angulated abutments/Angled abutments
  • CAD/CAM abutments
  • Custom abutments
  • Castable abutments
  • Healing abutments/Healing cuffs
  • Nonangulated abutments
  • Prepable abutments
  • Multi-unit abutments
  • Transmucosal abutments
  • Prefabricated abutments
  • Zirconium dioxide abutments (standard or customized)
  • Temporary abutments

Abutment swapping

Syn: Platform switching

This term refers to using an abutment that has a narrower diameter than the platform of the dental implant itself. Using this method, the dentist can move the implant-abutment junction away from the platform’s edge. The goal of abutment swapping is to prevent crestal bone loss and to increase the soft tissue volume around the platform of the implant. By using an abutment that is smaller than the dental implant platform, any inflammation that occurs will be farther from the crestal bone; thus, preventing peri-implant bone loss due to inflammatory responses.

A thick crestal bone ensures that the implant remains stable and stability is essential for the long-term success of a dental implant, which is why preventing bone loss is so important. When platform switching is utilized, the bone and tissue surrounding the dental implant is preserved, helping to provide patients with exceptional aesthetic results.

Abutment transfer device

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.).

Abutment-implant interface

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.

Abutment-level impression

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.

Access Hole

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.

Accessory ostium

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

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)