Endodontic treatment, or root canals, are a common, although often dreaded, dental procedure. They are often successful at preserving a natural tooth instead of having it extracted, which can cause bone loss and other complications. Endodontic treatment was introduced by Hermann in the 1920s, when he outlined the administration of calcium hydroxide for pulp therapy. This essentially created the foundation for modern endodontic therapy as it is known in dentistry today. Ideally, the outcome of a root canal is the removal of diseased pulp and the replacement of healthy pulp that begins to regenerate itself. To control the differentiation, metabolism, and proliferation of stem cells and to provide spatially correct positioning, appropriate scaffolding is necessary. Different types of scaffolding facilitates the regeneration of various tissues, making it critical that the treating dentist has a robust knowledge of which scaffolding is suitable for the type of tissue attempting to be regenerated.

Scalloped Implant

A scalloped dental implant is an older style of implant that was created to biologically facilitate and guide interproximal bone remodeling during procedure healing and to retain papillae and bone height during functional loading. The scalloped implant design includes areas for both soft and hard tissue apposition, which are set parallel to each other, mirroring the cementoenamel junction. The area for the apposition of hard tissue is meant to facilitate osseointegration, while the area for soft tissue is designed to create a space for the subgingival margin of the restoration and to support various connective tissues. While the design was well-intentioned, it did not work as well as expected during application. A study of 17 scalloped implants that were evaluated for 18 months revealed that the scalloped design increased bone loss more than conventional dental implants that were properly placed. There were no differences in papillae formation in the study.

Scanning abutment

A scanning abutment is a type of abutment that is used to transmit data related to the angulation and position of seated implants. The data is collected with a digital desktop scanner or an intraoral scanner and is extremely accurate. A scanning abutment includes a biocompatible abutment body. Inside the body is an internally threated titanium screw, which is designed to be compatible with other materials and components used within the specified dental implant system. There are two types of scanning abutments: clinical scanning abutments and laboratory scanning abutments. The former contains barium, a radiopaque material, and is designed to be used with intraoral scanners. The latter contains radiolucent material and is used with both blue-light and red-light desktop scanners. Scanning abutments should be inspected for damage before use, and the use of multiple scanning abutments is not recommended due to the possibility of cross contamination.

Scanographic template

A scanographic template, also called a scanography template and sometimes spelled scannography, is a template created for the process of capturing digital images of an object. Typically, the purpose of the template is to create a printable image using a flatbed scanner with a charge-coupled (CCD) array capturing device. Scanograpy differs significantly from conventional document scanning by utilizing three-dimensional or atypical objects. In dentistry, scanography is a type of radiography that is used to produce images of the oral structures of a patient for the purpose of creating restorations. It can also be used as a diagnostic tool to detect abnormalities in the mouth and jaw, as well as tumors, cysts, impacted teeth, dental implant malalignment, caries (tooth decay), and other clinically significant issues. There are two types of scanography used in dentistry: rotational scanography and linear scanography. Linear scanography is used most often as it produces panoramic views.

Schneiderian Membrane

The Schneiderian membrane, also called the Schneiderian epithelium, is the lining of the paranasal sinuses and nasal cavity. It’s unique in that the ciliated columnar lining is ectodermally derived and features goblet cells. The neighboring respiratory epithelium, which appears similar to the Schneiderian membrane, is derived from the endoderm. One of the most common complications that can occur during a sinus grafting surgery is a tear or perforation in the Schneiderian membrane of the maxillary sinus. If this occurs, typically, the surgeon will repair the perforation at the same time the graft is placed, and few additional risks of complications exist. However, in some cases, patients will develop an infection in the maxillary sinus or surrounding areas of the maxillofacial complex after a substantial or complete tear in the membrane. This infection is serious and may result in the failure of a recently completed bone graft or dental implant.

Screw Fracture

For many decades, dental implants have been one of the most desirable ways to replace one or more missing teeth. Their outcomes are generally predictable, and the failure rate of dental implants is low overall. However, failure can still occur both in the short and long term. Screw fracture, or the fracture of the screw implanted into the bone to hold the dental prosthetic, is a common reason dental implants fail within the first 10 years. Although nearly half of dental implant patients suffer a screw fracture, removing it is a complex procedure, especially if the screw is fractured or broken in more than one place. Considered a mechanical complication, the fracture of a dental implant screw is often caused by high occlusal loads. In cases of bruxism, where there is constant pressure on the teeth from clenching or grinding them (usually at night), screw fractures are more common.

Screw Implant

A screw implant is a threaded root-form dental implant which can either be parallel-sided or tapered. A screw implant is placed into the bone of the jaw to replace the root of a missing tooth. After the screw implant is positioned, gum tissue is placed over it and allowed to heal, sometimes for up to 6 months. A second procedure is usually then required to affix the abutment and the crown. The screw implant is generally made of a material such as titanium that is biocompatible and capable of fusing with the surrounding bone during osseointegration. At times, a patient may require a bone graft prior to the placement of the screw if the existing bone is not substantial enough to support the implant by itself. Complications such as peri-implantitis may occur following a screw implant. This condition causes inflammation and can lead to bone loss around the implant and to implant failure.

Screw Joint

A screw joint is the junction of two parts held together by a screw (e.g., implant-abutment screw joint). In implant dentistry, the screw joint is an essential part of the implant or prosthesis, however, it is also susceptible to loosening over time. This can cause implant failure at the screw joint. A screw at the screw joint may become loose for several reasons which include incorrect fit of the prosthesis, excessive loading, poor screw design, improper placement, inadequate torque on placement, poorly made prosthesis components, and improper design of the restoration. For those factors which can be controlled by the dental professional, exact adherence to protocols should be maintained to ensure screw joint failure isn’t caused by an error on placement. A basic understanding of the physical forces that act on the screw joint in a prosthesis is extremely helpful for the dental professional as it provides information on how screw joint loosening can occur.

Screw Loosening

Screw loosening is a prosthetic complication whereby a screw loses its preload causing the loosening of a restoration or abutment. Due to the many forces exerted on a screw in an implant, a variety of issues may occur that contribute to screw loosening. These forces include the bite angle of the patient, loading of the implant, and the functional tension, rotation, and force on the screw. There are other factors that can contribute to the loosening of an implant or abutment screw as well. Some of these factors include the design of the implant, the design of the abutment, the amount of torque used to secure the screw, the efficiency of the implant’s manufactured parts, and the fit of the implant. While manufacturer errors may not be something the dental professional can control, they should follow all protocols when placing the implant and the screw to avoid improper torque, positioning, or incorrect loading.

Screw preload

Screw preload is the clamping or stretching force that occurs across the interface of the implant components that are being attached via screw tightening. Screw preloading has been shown to increase the screw’s fatigue strength as well as improve the locking effect. To set the screw preload within its optimal range, the correct amount of torque must be applied. However, this can be a complicated process as the torque applied in preloading a screw can be affected by a variety of factors. These factors include the material which the screw is made of, the screw’s stiffness, construction, and shape, the integrity of the screw and joint, and the condition of the surrounding surfaces. A screw’s level of preloading should be more than the biting force but less than the elastic limit and may fall within a 75-90 percent range of the material’s elastic limit to prevent the screw from loosening under moderate loads.