Preprosthetic surgery remains a work horse of dentoalveolar surgery. Advances in rehabilitation of the edentulous mouth with the use of endosseous osseointegrating dental implants and dermal matrix substitutes have changed the narrative of traditional preprosthetic surgery while maintaining some fundamental principles. An outline of the basic techniques in preprosthetic dentoalveolar surgery is discussed in the setting of these technological and tissue engineering advances.
Preprosthetic dentoalveolar surgery continues to be an important factor in successful rehabilitation of the oral cavity.
Anatomic considerations in preprosthetic surgery.
Hard-tissue preprosthetic surgical techniques.
Soft-tissue preprosthetic techniques.
Skin substitutes in preprosthetic surgery.
Rehabilitation of the dentition has been an ongoing process as far back as 700 BC, which often referred to removal of disease and replacement of the lost structures to restore function. Preprosthetic surgery is a vital component to achieving the goals of restored dentition. Regardless of whether it was the prehistoric times or the era of osseointegrating implants, most patients require some aspect of preprosthetic surgery when an attempt is made for oral rehabilitation. This rehabilitation of the edentulous patient can pose significant challenges to the restorative dentist and surgeon. The intent of this article is to discuss preoperative patient planning, preprosthetic surgical options, and other relevant considerations.
Complete or partial edentulism is known to be more common in the aging population. The surgical management of the condition demands a thorough preoperative assessment to ensure both medical risk stratification and optimization before rendering safe surgical treatment. Thus, the initial evaluation entails the investigation of any medical comorbidities and a deep dive into the overall health of the patient. During the physical examination, the patient should undergo a standard head and neck evaluation with a focus on the unique anatomic consideration of the edentulous condition, including asymmetries of the maxilla or mandible, gingival type and mucosal quality, presence of maxillomandibular tori and exostoses, high frenum attachments, interarch space, vestibular depth, and vertical dimension of occlusion. The use of standardized classification systems such as the one introduced by Cawood and Howell can help standardize the evaluation of the edentulous ridge anatomy. Traditionally, the data collection process required standard stone models for surgical planning and prosthetic fabrication. However, current technological advancements, such as with cone beam computed tomography scan and intraoral scanner, have modernized data collection processing to an incredibly accurate level, bypassing the need for alginate impressions and stone models. ,
Anatomic changes with edentulism
Understanding the unique maxillomandibular edentulous anatomy and its differences from its dentate counterpart is vital to the success of surgery. Edentulous ridges resorb significantly with time, and with time there is a significant reduction in both bulk and quality of available bone stock, and with resorption, the inferior alveolar canal and foramen are positioned more superiorly in the mandible. The foramen can have variable presentations of its anatomic location. The genial tubercle can become more superiorly positioned. With edentulous, aging, and bony atrophy, the vascular support to the mandible shifts from a centrifugal to a centripetal arrangement.
In the maxilla, there may be little bone between the crest of the ridge and the nasal floor. Similarly, the posterior maxilla in the region of the maxillary sinuses may have minimal bone between the crest of ridge and the sinus cavity. The entire ridge may seem flat and confluent with the palatal shelf in severe and chronic edentulism.
Indications for surgery
The edentulous ridge of the maxilla and mandible resorb differently among individuals but generally follows a similar pattern. The maxilla resorbs on the facial surface and the inferior surface of the alveolar ridge. The mandible resorbs in an inferior and anterior pattern. These resorptive patterns can yield a ridge that is unable to accommodate a denture.
The following circumstances can necessitate a surgical procedure to ensure smooth ridges with adequate width and height for denture retention:
Maxillary palatal torus
Mandibular or maxillary exostoses
Overhanging maxillary tuberosities
Severe bony undercuts
Knife edge ridges
Alveoloplasty can be completed in order to flatten the bone and allow for a larger “shelf” of bone for the denture. Soft tissue may also require augmentation before restoration fabrication. With conventional dentures, vestibular sulcus depth is of utmost importance. Shallow sulcus depth will require a vestibuloplasty.
Other instances of soft tissue indications may include
Hyperplastic maxillary tuberosities,
Epulis fissurata, or
Unfavorable frenum attachments.
In the patient with dental implants adequate tissue height and thickness is a necessity. Soft tissue augmentation in the form of vestibuloplasty, keratinized tissue augmentation, or lowering of the floor of the mouth may be required.
Once the decision has been made to proceed with preprosthetic surgery, the goal is to establish ideal hard and soft tissue contours. The bony ridge should be U-shaped with adequate height and width without undercuts, protuberances, or sharp edges. The oral mucosa should have adequate thickness with appropriate buccal and lingual depth. ,
A common procedure before denture fabrication is mandibular tori removal ( Fig. 1 ). The procedure may be completed in the ambulatory setting under general anesthesia or local anesthesia. Excessive tori may pose more of a surgical challenge and be better addressed in the operating theater. Regardless of the setting, establishing profound local anesthesia is imperative. In general, the initial incision involves making a crestal incision and reflecting a full-thickness mucoperiosteal flap. In the case of bilateral mandibular tori, the crestal incision is carried from the posterior right alveolar ridge to the posterior left alveolar ridge. If needed, a buccal hockey-stick releasing incision may be completed to the posterior extent. A full-thickness mucoperiosteal flap is elevated on the lingual surface of the mandible, exposing the tori. Delicate soft tissue management is imperative, as trauma to the lingual mucosa complicates the postoperative recovery. After the tori are exposed and adequately visualized, a Seldin retractor is placed between the exposed lingual surface of the mandible and the lingual mucosal flap in order to protect the lingual tissue.
There are several methods to remove the bony protuberances. A rongeur can be used to snip the exostoses. A drill using a pineapple-shaped bur under copious irrigation may be used instead. Most surgeons prefer to score the superior aspect of the protruding bone with surgical drill and a fissure bur with irrigation. A chisel with mallet is then used to removal the tori. After the initial ostectomy, a bone file or handpiece with bur may be used to level any remaining undercut ( Fig. 2 ). Digital palpation of the lingual surface of the mandible is performed to assess the smoothness of the remaining structure and the presence of residual undercuts or projections. After bone removal is completed, the area is thoroughly irrigated to remove unwanted debris. The area is checked for hemostasis. The mucosal flaps are then closed in running fashion with resorbable sutures. This technique, largely reliant on diligent soft tissue management, can be used for any bony protuberance in the maxilla or mandible.
Maxillary Palatal Torus
A thorough discussion with the restorative dentist is necessary before proceeding with surgical removal. At times, surgery can be avoided with a well-fitting denture in the presence of the tori. The technique for removal of a palatal torus is predominantly based on clinical presentation ( Fig. 3 ). As with mandibular tori, these cases can be addressed in the ambulatory or operating room setting under general or local anesthesia depending on the extent of surgery required. Given that this procedure can be highly stimulating and may result in excess bleeding, additional precautions should be undertaken with surgery in the ambulatory setting, especially in the presence of an open-“guarded” airway and the potential respiratory sequelae. A protected airway with endotracheal tube may be necessary when the removal of the torus is suspected to be more demanding than routine.