Examination and planning before dental implantation

Preparation and diagnostic imaging

The presence of caries, stomatitis, xerostomia, gingivitis, or leukoplakia in the oral cavity is associated with a high risk of inflammatory complications. A mandatory step is complete sanitation and treatment of periodontal tissues. Functional disorders, such as macroglossia, temporomandibular joint (TMJ) pathologies, and malocclusion, must be accounted for in the treatment plan, while bruxism and poor hygiene are major additional risk factors.

Instrumental planning relies on diagnostic imaging:

• Computed tomography (CT): This is the method of choice. It makes it possible to analyze the jaw in vertical and horizontal slices, providing a precise spatial understanding of the anatomy.
• Panoramic radiography (OPG): Frequently used, but has pronounced drawbacks. The method does not allow for the evaluation of alveolar ridge width and distorts real dimensions of structures by 25–75%. To estimate bone height using OPG, a marker of a known size is preliminarily fixed to the mucosa.

Important: In modern practice, significant bone atrophy is no longer considered a contraindication, as current surgical techniques allow for working with any initial anatomical data.

Surgical positioning principles

To ensure the long-term stability of the metal support, strict rules are followed:

1. Bicortical fixation. It is preferable to stabilize the structure between two dense cortical layers. The first support is the crest of the alveolar ridge. The second support is the base of the mandible (in the anterior region), the lower wall of the maxillary sinus, or the nasal base. Relying on the cortical plate of the mandibular canal is strictly prohibited.
2. Angles and parallelism. Implants must stand parallel to each other and to the remaining teeth in the arch. If the difference in the inclination of the supports exceeds 30°, adequate prosthetics will be impossible (masticatory load will not follow the vertical axis). The inclination itself should mimic the natural one: a slight lingual inclination in the mandible and buccal in the maxilla.
3. Surrounding tissues. At least 1.5 mm of free space must be preserved on all sides between the implant edge and the adjacent bone (and up to 2 mm in the coronal part). The distance between the implants themselves must be a minimum of 2–3 mm. If these volumes are deficient, bone atrophy around the neck of the implant will inevitably develop.

Calculation of the number and size of supports

The total contact area between the titanium support and the bone is significantly smaller than that of natural roots (20 cm² vs 45 cm²). To avoid overloading the bone tissue, it is necessary to install the maximum number of implants, guided by the anatomy of the missing teeth.

• Partial edentulism: When anterior teeth or premolars are lost, 1 implant is installed. When a molar is lost, it is preferable to place 2 implants. If a single one is placed, its diameter must be at least 4 mm (optimally 5–6 mm). The absolute minimum diameter for any single restoration is 3.75 mm; thinner devices break under overload.
• Full edentulism: To fix bridges on an edentulous mandible, a minimum of 6 supports is needed (this is the maximum number that physically fits between the mental foramina). For the maxilla, a minimum of 8 supports is required. The length of the devices must be at least 10 mm. At the same time, the effectiveness of implantation in the maxilla is generally lower than in the mandible.

Methods and timelines of osseointegration

After tooth extraction, the physician can take two paths: perform delayed implantation (into already remodeled bone) or immediate implantation (into the socket of a freshly extracted root). The immediate technique shortizes timelines and allows for a thicker implant, but is contraindicated in suppurative inflammation, bone loss, and requires ideal sanitation.

According to the surgical approach, the following are distinguished:

• Two-stage technique: Universal, with proven efficacy, but requires two surgeries and carries the risk of cover screw exposure.
• Single-stage technique: Less traumatic, but requires flawless initial stability. Not suitable for acute bone ridges and a small volume of attached gingiva.

Standard waiting periods (without load) are 3 months for the mandible and 6 months for the maxilla — during this time, osteoblasts and osteoclasts form the bond between bone and metal. In soft bone, this period is increased. However, modern protocols aim to shorten timelines by 2–3 times, down to immediate loading (on the day of surgery or a week later), provided there is ideal primary stability and no bruxism.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Criteria for choosing single-stage and two-stage implantation techniques
• Protocols for guided bone regeneration
• Biomechanical features when implant axes diverge by more than 30°
• Immediate loading tactics in complete edentulism

Other topics from the section "Chapter 17. Dental Implantology (V.I. Olesova)"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.