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Features of the surgical stage of dental implantation under complex anatomical and topographic conditions of the lower jaw

Features of the surgical stage of dental implantation under complex anatomical and topographic conditions of the lower jaw



Authors: O. Doroshenko, V. Klimentyev
Partial and complete tooth loss is one of the most common pathologies of the dentition, especially in the elderly. The generally accepted method for replacing dentition defects using traditional prosthetics methods, namely the manufacture of partial and complete removable dentures, does not always satisfy patients.
From this point of view, the manufacture of orthopedic constructions based on dental implants is promising.
Very often, tooth loss is accompanied by significant atrophy of the alveolar processes and complex anatomical and topographic conditions, while the installation of dental implants becomes a rather difficult problem.
Today, there are such possible options for dental implantation under difficult anatomical and topographic conditions of the lower jaw:
  • the use of implants (subcortical, disk, transmandibular), accompanied by a significant number of complications;
  • subperiostal implantation;
  • the use of techniques for circumventing anatomical obstacles;
  • use of bone regeneration techniques;
  • bone grafting;
  • transposition of the mandibular nerve, which allows you to create optimal conditions for the installation of implants, but there is a risk of damage to the nerve membrane and its trunk.
  • Recently, literature has published evidence of the successful functioning of immediately loaded and functioning implants in patients with toothless jaws. Immediate implantation involves combining two surgical steps into one — tooth extraction and implant placement, which is performed simultaneously and prevents the resorption of the alveolar bone. With this operation, the implant can be located in an ideal position close to the position of the extracted tooth, in the direction most favorable for the perception of chewing load on the supporting bone.
Immediate implantation compensates for the patient a negative psychological effect due to tooth extraction, especially when they are last on the jaw. In addition, the patient has the opportunity to start using dentures almost immediately, and not after a long period after tooth extraction and the installation of classic implants. The number of visits to the dentist and the cost of treatment are also reduced.
The stability of the implant and the prognosis of its functioning is better, the larger the bone-implant contact area.
At the moment, there is no consensus and an approved clinical protocol for determining the length and diameter of an implant to replace one or another tooth.
Quite often, after atrophy of the alveolar ridge, the position for implant placement becomes very problematic due to the thin alveolar ridge or closely located anatomical formations, namely the lower alveolar nerve. Impaired nerve function can occur with direct perforation of the canal and trauma during the formation of the implantation bed, as well as due to compression of the nerve by postoperative edema or dental implant. These complications are manifested in the absence or prolonged change in the sensitivity of tissues in the innervation zone, the development of pain syndrome of various intensities, and is also accompanied by emotional and stress disorders and significantly worsens the patient's quality of life.
The location of implants with a length of 10 mm in case of atrophy of the alveolar ridge is problematic, and the use of short implants (length: 5 7-8, 5 mm) leads to a large number of complications. As for implants of small diameters (3.75 mm), their use is limited by certain criteria, but at the moment there is not enough scientific work with a long term of monitoring the effectiveness of their use.
Only careful planning of surgical intervention with computed tomography and manufacturing of surgical templates can ensure that there are no complications during surgery if dental implants are installed in the lateral section to bypass the mandibular nerve.
A high percentage of complications during dental implantation in the lower jaw with complex anatomical and topographic conditions for the manufacture of fixed orthopedic structures indicates that this problem has not been studied enough, and the results of the studies have not been unified.
Therefore, the aim of our study was the rehabilitation of a patient with complex anatomical and topographic conditions of a toothless lower jaw by applying the proposed algorithm for surgical dental implantation.
Patient S., born in 1960, contacted the European Dental Center with complaints of a lack of teeth in the lower jaw in order to install a fixed orthopedic design with support on implants. The patient has a history of prolonged use of a partial denture.
On the opposite jaw — ceramic-metal fixed bridges with support on 16, 14, 13, 12, 11, 21, 22, 23, 24 and 27 teeth.
In order to determine the possibility of manufacturing a fixed orthopedic structure supported by dental implants, computed tomography was performed (Fig. 1).

                                                                statji1 statji2

Fig. 1 — Computed tomography of the lateral region of the lower jaw before treatment
The study showed that the patient had type I bone tissue according to the classification of Lekholm and Zarb.
In the lateral areas where implant placement is planned, the alveolar ridge is 10.63 mm wide and 12.60 mm high. The distance from the cortical plate to the mandibular canal is only 4.84 mm.
It was decided to manufacture a fixed orthopedic design with support on 8 implants.
The installation in this clinical case of implants in the lateral region bypassing the mandibular canal is possible only under the condition of computed tomography with the determination of the exact location of the canal and the subsequent manufacture of a surgical navigation template.
The operation of dental implantation was planned virtually in the DDS-Pro CT scan, model scan and wax-up. In the distal parts of the lower jaw, single-stage screw implants with cortical fixation bypassing the mandibular canal were installed, and in the front part, implantation with root-shaped implants with a screw intraosseous part was performed. The length of the intraosseous part of all implants is 10 mm, the thickness is 3.0 mm.
After implant placement, computed tomography was performed to confirm the correct placement of the implants (Fig. 2, 3).

           statji3          statji4     statji5           statji6 А
Fig. 2 — CT after implant placement (A — right side, B — left side) of the implant location (Fig. 2, 3).
 statji8 statji9 statji10А
Fig. 3 — CT after implant placement (A — central area, B — right side)

The surgical stage of dental implantation provided for immediate functional load with a temporary fixed composite prosthesis with a plastic coating, which the patient was able to use already 3 days after the surgery. A sufficient number of implants of considerable length, the practical correspondence of the axes of the prosthesis and the implants virtually eliminates the occurrence of such risks as reducing the reliability of the prosthesis retention, fractures of the implant and inadequate functional load on them.
The effectiveness of the treatment was determined by clinical and radiological criteria (Albrektsson and coll).
The postoperative period was uneventful, the condition of the mucous membrane around the implants was satisfactory. The patient did not show any complaints.
Clinically, the patient was determined immobility of the implants, the absence of negative manifestations during percussion, the absence of pain infection around the implants and the absence of paresthesia.

                                                                                          statji11   statji12                                                                      Fig. 4 — Clinical picture of the oral cavity on the second day after implantation


                                                                statji13                    statji14                                    Fig. 4.1 — Immediate prosthetics on the third day after surgery with temporary non-removable metal-plastic structures.

X-ray throughout the observation period, the absence of bone resorption sites around the intraosseous part of the implant and the minimal loss of bone tissue during the period of functioning of the implant were determined (Fig. 5).

                                                                                                         statji15OCG before dental implantation
                                                    statji16              statji17                                                  OCG on the 3rd day after implantation
                  OCG 6 months after implant placement

Fig. 5 — X-ray examination before and at certain times after dental implantation
Similar data were obtained during CT scan after 6 months.

statji18 statji19
 statji20А Central plot
Б Right side
  statji21 В Left side
 Fig. 6 — CT 6 months after implant placement (A is the central section, B is the right lateral side, C is the left lateral side of the alveolar bone)

After 6 months of using the temporary design, the patient was fixed in the oral cavity with a permanent fixed fixed structure supported by dental implants
Thus, careful planning of the surgical intervention with computed tomography ensured that there were no complications during the surgical intervention in the case of the installation of one-stage root-shaped implants: in the lateral section — bypassing the mandibular nerve, and in the central section — in the holes of the extracted teeth.
This minimally invasive technique can be applied to patients who want to reduce the number of surgical interventions, reduce the number of visits to the dentist and the duration of treatment with the ability to use a fixed orthopedic design immediately after the installation of dental implants.
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