RU2849130C1 - Method for determining the donor site of the mucosa of the hard palate - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention can be used for personalised determination of a safe donor site on the mucous membrane of the hard palate for cutting out a connective tissue graft. Based on the diagnostic plaster model of the patient's upper jaw, an individual transparent palate cap is made. Then, in the patient's oral cavity, the hard palate is conditionally divided into six areas of investigation on each side of the midline. Next, using high-frequency Doppler ultrasound, the mucous membrane of the hard palate is examined, and in each conditionally designated study area, one point corresponding to the location of the greater palatine artery is found and marked. Next, a transparent cap is placed on the patient's upper jaw and pressed against the patient's upper palate, imprinting the marker points of the artery's location on its inner surface. The trajectories of the location of the greater palatine artery are determined on the cap by connecting the points. Then, on the cap, on each side of the middle of the palate, parallel to the line characterising the location of the greater palatine artery, 2 mm away from it towards the dental arch, a second line is drawn, and parallel to the gingival margin, 2 mm apically from it, a third line is drawn. After that, in the projection of the canine and third molar, parallel to the axis of the teeth, draw lines connecting the second and third lines. Cut out a hole corresponding to the shape of the donor site along the resulting contour, without intersecting the greater palatine artery.

EFFECT: to minimise surgical complications, ensures clear visualisation of the surgical field without excessive bleeding into the wound, and reduce the duration of the surgical procedure.

1 cl, 4 dwg, 3 ex

Description

The invention relates to medicine, namely to surgical dentistry, and can be used for personalized determination of a donor site of the mucous membrane of the hard palate for cutting out a connective tissue graft.

The hard palate mucosa is a popular donor site for flaps and connective tissue grafts used to close small defects in the palatoalveolar complex mucosa and to increase the thickness and correct the width of the keratinized gingiva.

However, when performing tissue dissection in this area, there is a high risk of damaging the greater palatine artery.

The greater palatine artery is a paired artery with a diameter of 1-2.5 mm that directly supplies blood to the mucous membrane of the hard palate and is located between the periosteum and the proper plate of the mucous membrane of the hard palate, in shallow bony grooves.

The complex relationships between the mucous membrane and the bony base of the hard palate, as well as the variability of the morphometric parameters of the palatoalveolar complex, determine the topographic and anatomical variability of the trajectory of the localization of the greater palatine artery.

Injury to an arterial vessel leads to excessive bleeding from the wound surface, impaired visualization of the surgical field, and increased surgical time. These factors increase the likelihood of postoperative necrosis of the donor site wound surface and can also negatively impact the quality of the graft, directly affecting the outcome of the surgery.

In order to prevent this type of complication, the doctor must conduct additional diagnostic methods in order to have an accurate understanding of the individual characteristics of the localization of the large palatine arteries in the patient and, based on this knowledge, select the surgical area outside of their localization.

A known technique for ultrasound angiography is color Doppler mapping, energy mapping, harmonic imaging techniques, artificial contrast enhancement using intravenous contrast agents, and three-dimensional vascular reconstruction. Ultrasound angiography allows for noninvasive visualization of various vascular structures, the study of vascular patterns, the assessment of their nature, the monitoring of the accumulation and elimination of contrast agents, and the study of hemodynamics. Linear scanning transducers L 9-5 and 17-5 (with an operating frequency of 5-17 MHz) are used for ultrasound examination of soft tissues in the maxillofacial region. Their advantage is good resolution, but their disadvantage is the large scanning surface area, which varies from 4.0 to 6.0 cm or more. It is not possible to place such a transducer in the oral cavity.

A method for ultrasound examination of the oral soft tissues is available using the L 15-7 io intraoral linear transducer (with an operating frequency of 7-15 MHz) (RU 2411006, published February 10, 2011). The pencil-type intraoperative linear transducer has a small diameter and is long enough to be positioned inside the patient's oral cavity.

However, using such a probe to study the trajectory of the greater palatine artery, which projects onto the mucous membrane of the hard palate, is quite challenging. The probe aperture, 23 mm, covers a significant portion of the mucous membrane of the hard palate, preventing a multi-positional study.

Thus, the main disadvantage of the ultrasound angiography method is the impossibility of its use in identifying the trajectory of the large palatine artery on the mucous membrane of the hard palate due to the dimensional and technical features of the ultrasound sensors.

Computed tomography and magnetic resonance angiography are known in the art, providing objective information on the condition and location of blood vessels in the head. However, these methods involve ionizing radiation and the use of a contrast agent, leading to absolute and relative contraindications for these diagnostic methods. Therefore, their use is justified in diagnosing malformations, injuries, and other pathological conditions of the vascular bed.

The disadvantages of these methods in relation to the study of the large palatine artery are the difficulties in visualizing small diameter vessels due to their tortuous course and the lack of practice in conducting research for these purposes.

A method of cone-beam computed tomography of the maxillofacial region (hereinafter CBCT) is known from the prior art.

When planning flap surgeries in the palatoalveolar complex, the use of CBCT allows one to determine the localization of the anatomical openings of the hard palate, corresponding to the localization of the vessels and nerves emerging from them, and to assess the relief of the bony palate and the thickness of the mucous membrane.

The localization of the greater palatine artery is determined by the greater palatine foramen, the relief of the hard palate, the presence of the palatine spine, and the grooves that are observed on computed tomography scans.

However, accurately identifying the location of the greater palatine artery after its exit from the greater palatine foramen can be quite challenging, as the palatine sulci cannot always be traced along its entire length in the projection of the donor site being examined, or, conversely, multiple sulci can be visualized. The angle formed by the alveolar and palatine processes of the maxilla is not always clearly defined. Due to the low contrast of soft tissues, to achieve diagnostic results, it is necessary to use radiopaque agents in soft tissues, such as iodinated contrast agents, ExiTron™ nano 12000 contrast agent, iogexol, and others.

The disadvantage of this method is the high noise level of the image and the impossibility of determining the location of the large palatine artery along its entire length due to the absence of bony landmarks on the vault of the hard palate.

A prototype method for digitally planning the harvesting of hard palatal mucosa grafts (RU 2756080, published September 27, 2021) is known. The method involves performing a CBCT scan of the maxilla and scanning the dental arches. By analyzing the CBCT data and combining it with a digital model of the maxilla, a computer program module is used to create virtual navigation templates with the contours of the future grafts. These virtual models of the trays are converted into physical models using an additive computer-aided 3D printing method and are used to make mucosal incisions.

The disadvantages of this method include its inability to identify the location of the greater palatine artery along its entire length due to variations in the bony palate. It also produces high image noise, is labor-intensive, and requires expensive equipment and specialized physician training or the involvement of third-party medical organizations.

The objective of the present invention is to develop a method for determining a safe donor site for the patient in the mucous membrane of the hard palate for collecting a connective tissue graft in the region of the palatoalveolar complex in order to minimize surgical complications.

This problem is solved due to the fact that in the method of determining the donor site of the mucous membrane of the hard palate, including the allocation of a safe donor site, the manufacture of an individual transparent mouthguard for the palate, the collection of a connective tissue graft, there are differences in that, according to the obtained diagnostic plaster model of the patient's upper jaw, an individual transparent mouthguard is made for the palate, then, in the patient's oral cavity, the hard palate is conditionally divided into six areas of study on each side of the midline, then, using high-frequency ultrasound Dopplerography, the mucous membrane of the hard palate is examined and in each conditionally allocated area of study, one point is found corresponding to the localization of the large palatine artery and marked, then a transparent mouthguard is placed on the patient's upper jaw, pressed against the patient's upper palate, imprinting marker points of the artery localization on its inner surface, determine the trajectory of the localization of the large palatine artery on the splint, by connecting the points, then on the splint on each side from the middle of the palate parallel to the line characterizing the localization of the large palatine artery, stepping back from it 2 mm towards the dental arch, draw the second line and parallel to the gingival margin, at a distance of 2 mm apically from it, draw the third line, after which in the projection of the canine and third molar, parallel to the axis of the teeth, draw lines connecting the second and third lines, along the resulting contour, cut out a hole corresponding to the shape of the donor site, not intersecting with the large palatine artery.

The technical result is to minimize the risk of arterial dissection, ensure clear visualization of the surgical field without profuse bleeding into the wound, and reduce the time of surgical intervention.

The invention is illustrated by the following drawings:

Fig. 1 shows an example of fixing the detected localization points of the large palatine artery on the mucous membrane of the hard palate with a 1% aqueous solution of methylene blue.

Fig. 2 shows an example of transferring a transparent protective splint with colored localization points of the greater palatine artery to a diagnostic model of the upper jaw, where 1 is a plaster model of the patient's upper jaw; 2 is an individual transparent protective splint for the palate; 3 is the localization point of the greater palatine artery, colored with a marker of 1% aqueous solution of Methylene blue.

Fig. 3 shows an example of lines on the kappa that characterize the localization of the large palatine arteries.

Fig. 4 shows an example of the contour of the donor site of the mucous membrane of the hard palate, not intersecting with the greater palatine artery.

In 80 cases requiring donor site determination in the hard palate mucosa, the locations of the greater palatine artery were identified on the hard palate mucosa using a 25 MHz transducer and stained with a 1% aqueous methyl blue marker. A custom-made transparent mouth guard was placed on the patient's upper jaw, and the identified locations were duplicated on its outer surface. The mouth guard was transferred to a plaster cast of the patient's upper jaw, and on its outer surface, parallel to the dental arch on each side of the middle of the hard palate, the marker locations were connected by a line characterizing the trajectory of the greater palatine artery in the given patient. By visualizing the location of the patient's greater palatine artery on the mouth guard, the physician can create a customized contour of a safe donor site: a second line is drawn on the mouth guard parallel to the line characterizing the location of the greater palatine artery, approximately 2 mm from the dental arch. Next, a third line is drawn apically, parallel to the gingival margin and approximately 2 mm away. In the projection of the canine and third molar, lines are drawn parallel to the long axis of the teeth, thereby connecting the second and third lines.

Thus, the doctor received an individual outline of the donor site, which did not intersect with the large palatine artery, and could plan the future size and shape of the transplant.

Then, using a scalpel, a hole was cut out on the cap along the selected contour, corresponding to the safe donor site.

The mouthguard was removed from the model and disinfected. Then it was put back on.

on the patient's upper jaw, and within the formed hole in the mouth guard, under local anesthesia, the doctor made incisions in the mucous membrane to collect a connective tissue graft.

When collecting the connective tissue graft within the donor area of the mucous membrane of the hard palate determined by the proposed method, in all cases there was no profuse arterial bleeding from the wound.

The method is carried out as follows.

The first stage involves creating a diagnostic plaster model of the patient's upper jaw. A custom-made transparent protective palate guard is fabricated using a vacuum former based on the plaster model. Next, the patient's hard palate is divided into six areas on each side of the midline: the third molar projection; the second molar projection; the first molar; the second premolar; the first premolar; and the canine area.

Next, high-frequency Doppler ultrasound is used with a Minimax-Doppler K computerized device and a 25 MHz ultrasound transducer to examine the mucous membrane of the hard palate to locate the arterial vessel in each designated area. One arterial location is identified in each area and stained with a 1% aqueous methylene blue solution (Figure 1).

Next, a transparent mouthguard is placed on the patient's upper jaw and pressed against the patient's upper palate, imprinting marker dots indicating the artery's location on its inner surface. Simultaneously, the dots are duplicated on the outer surface of the mouthguard using a 1% aqueous methylene blue marker. The mouthguard is then transferred to a plaster model of the upper jaw (Fig. 2), and on its outer surface, parallel to the dental arch on each side of the middle of the palate, the marker dots are connected with a line (Fig. 3).

Next, a second line is drawn on the tray on each side of the midpalate, parallel to the line characterizing the location of the greater palatine artery, approximately 2 mm toward the dental arch. A third line is then drawn parallel to the gingival margin at a distance of approximately 2 mm apically from it. In the projection of the canine and third molar (if the third molar is absent, a line is drawn in the projection of the outermost tooth on the side being examined), lines are drawn parallel to the long axis of the teeth, thereby connecting the second and third lines. This creates a customized donor site contour (Fig. 4), along which a hole is cut with a scalpel. This hole corresponds to the shape of the donor site and does not intersect with the greater palatine artery. The tray is removed from the model and disinfected. This tray is then placed on the patient's maxilla, creating an open area of mucosa that precisely corresponds to the safe donor zone, within which the connective tissue graft is collected.

Thus, the proposed method allows for the safe and accurate determination of the maximum safe donor site of the hard palate mucosa, within which the physician can safely collect the connective tissue graft without the risk of damaging the arterial vessel.

Clinical example 1. Patient A., 35 years old. Came with complaints of gum atrophy in the area of the upper jaw teeth, exposed tooth roots, and sensitivity to temperature stimuli.

An examination of the dental system and oral cavity was performed. A diagnosis of multiple gingival recessions in the anterior maxillary region (Miller Classes 1 and 2) was made. Surgical correction of the gingival recession using a connective tissue autograft of the hard palate mucosa was prescribed.

A diagnostic plaster model of the patient's upper jaw was made. A custom-made transparent protective palate guard was fabricated using the plaster model.

Using high-frequency Doppler ultrasound, the location of the greater palatine artery, projecting onto the mucous membrane of the hard palate, was studied in the patient's oral cavity in the area of teeth 18, 17, 16, 15, 14, 13, 28, 27, 26, 25, 24, and 23. The identified artery locations were stained with a 1% methylene blue solution. A transparent mouthguard was placed on the patient's upper jaw, and the obtained points were transferred to it. The mouthguard was then placed on a plaster model, and a line was drawn connecting the plotted points parallel to the dental arch on each side of the midpalate, thereby obtaining the trajectory of the greater palatine artery.

Next, a second line was drawn on the tray on each side of the midpalate, parallel to the line defining the location of the greater palatine artery, approximately 2 mm toward the dental arch. A third line was then drawn parallel to the gingival margin, approximately 2 mm apically. Lines were drawn parallel to the long axes of the teeth in the projections of the canine and third molar, connecting the second and third lines. Thus, the donor site contour was defined on the tray, along which a hole was cut with a scalpel. The hole matched the donor site shape and did not intersect with the greater palatine artery. After disinfection, the tray was placed on the patient's maxilla, creating an exposed area of mucosa. Within this area, a connective tissue graft was harvested under infiltration anesthesia. The graft was transferred to the recipient bed and secured with sutures.

No arterial bleeding was observed during the surgery. The surgical wound on the gum healed by primary intention, and the donor site wound healed under an antiseptic compress without signs of inflammation.

Clinical example 2. Patient G., 40 years old. Came with complaints of gum recession in the area of the anterior teeth of the lower jaw.

An examination of the dental and oral system revealed a low gingival attachment, the presence of connective tissue bands, and insufficient depth of the oral vestibule. A vestibuloplasty with an apical flap shift in the area of the aforementioned teeth and a free connective tissue autograft of the hard palate mucosa were prescribed.

A diagnostic plaster model of the patient's upper jaw was made. A custom-made transparent protective palate guard was fabricated using the plaster model.

Using high-frequency Doppler ultrasound, the location of the greater palatine artery, projecting onto the mucous membrane of the hard palate, was studied in the patient's oral cavity in the area of teeth 18, 17, 16, 15, 14, 13, 28, 27, 26, 25, 24, and 23. The identified artery locations were stained with a 1% methylene blue solution. A transparent mouthguard was placed on the patient's upper jaw, and the obtained points were transferred to it. The mouthguard was then placed on a plaster model, and a line was drawn connecting the plotted points parallel to the dental arch on each side of the midpalate, thereby obtaining the trajectory of the greater palatine artery.

Next, a second line was drawn on the tray on each side of the midpalate, parallel to the line defining the location of the greater palatine artery, approximately 2 mm toward the dental arch. A third line was then drawn parallel to the gingival margin, approximately 2 mm apically. Lines were drawn parallel to the long axes of the teeth in the projections of the canine and third molar, connecting the second and third lines. Thus, the donor site contour was determined, along which a hole was cut with a scalpel. The hole matched the donor site shape and did not intersect with the greater palatine artery. After disinfection, the tray was placed on the patient's maxilla, creating an exposed area of mucosa. Within this area, a connective tissue graft was harvested under infiltration anesthesia. The graft was transferred to the recipient site and secured with sutures.

No arterial bleeding was observed during the surgery. The surgical wound on the gum healed by primary intention, and the donor site wound healed under an antiseptic compress without signs of inflammation.

As a result of the surgical intervention, the depth of the vestibule of the mouth in the anterior part of the lower jaw was 8-9 mm.

Clinical example 3. Patient B., 25 years old. Came with complaints of gum recession in the area of tooth 15 of the upper jaw, exposure of the tooth root, sensitivity to temperature stimuli.

An examination of the dental system and oral cavity was performed. A diagnosis of gingival recession was made in the area of tooth #15 in the upper jaw. Surgical correction of the gingival recession using a connective tissue autograft of the hard palate mucosa was prescribed.

A diagnostic plaster model of the patient's upper jaw was made. A custom-made transparent protective palate guard was fabricated using the plaster model.

Using high-frequency Doppler ultrasound, the location of the greater palatine artery, projecting onto the mucous membrane of the hard palate, was studied in the patient's oral cavity in the area of teeth 18, 17, 16, 15, 14, and 13. The identified artery locations were stained with a 1% methylene blue solution. A transparent mouthguard was placed on the patient's upper jaw, and the obtained points were transferred to it. The mouthguard was then placed on a plaster model, and a line was drawn connecting the plotted points parallel to the dental arch, thereby obtaining the trajectory of the greater palatine artery on the mucous membrane of the right hard palate.

Next, a second line was drawn on the splint parallel to the line defining the location of the greater palatine artery on the right, approximately 2 mm from the dental arch. A third line was then drawn parallel to the gingival margin, approximately 2 mm from it, apically. In the projection of the canine and third molar, lines were drawn parallel to the long axis of the teeth, thereby connecting the second and third lines. Thus, the contour of the donor site was determined, along which a hole was cut with a scalpel. This hole matched the shape of the donor site and did not intersect with the greater palatine artery. After disinfection, the splint was placed on the patient's maxilla, creating an exposed area of mucosa. Within this area, a connective tissue graft was harvested under infiltration anesthesia. The graft was transferred to the recipient bed and secured with sutures.

No arterial bleeding was observed during the surgery. The surgical wound on the gum healed by primary intention, and the donor site wound healed under an antiseptic compress without signs of inflammation.

Thus, the proposed method is an accessible, non-invasive, highly informative way of determining the donor site of the mucous membrane of the hard palate with the possibility of its use in the dental chair during a clinical appointment with a dentist.

Claims (1)

A method for determining a donor site of the mucous membrane of the hard palate, including the allocation of a safe donor site, the manufacture of an individual transparent mouth guard for the palate, the collection of a connective tissue graft, characterized in that an individual transparent mouth guard is made for the palate according to the obtained diagnostic plaster model of the patient's upper jaw, then in the oral cavity of the patient the hard palate is conditionally divided into six areas of study on each side of the midline, then, using high-frequency ultrasound Dopplerography, the mucous membrane of the hard palate is examined and in each conditionally allocated area of study one point is found corresponding to the localization of the greater palatine artery, and it is marked, then a transparent mouth guard is placed on the upper jaw of the patient, pressed against the upper palate of the patient, imprinting marker points of the artery localization on its inner surface, the trajectories of the localization of the greater palatine artery are determined on the mouth guard, by connecting the dots, then on the cap on each side from the middle of the palate parallel to the line characterizing the localization of the large palatine artery, stepping back from it 2 mm towards the dental row, draw a second line and parallel to the gingival margin, at a distance of 2 mm apically from it, draw a third line, after which in the projection of the canine and third molar parallel to the axis of the teeth draw lines connecting the second and third lines, along the resulting contour cut out a hole corresponding to the shape of the donor site, not intersecting with the large palatine artery.