Indications for palatal sinus lift: Case series.

BACKGROUND: Open sinus lift is indicated in posterior maxilla when subantral bone is insufficient for insertion of dental implants. Lateral approach is the most used technique. Sometimes, this surgery is difficult due to thick buccal bone or other anatomic variations of maxillary sinus. AIM: The aim of this study was to determine cases that palatal approach open sinus lift is indicated. SETTINGS AND
DESIGN: This study was a retrospective study.
MATERIALS AND METHODS: Archive files of Dental Implant Department of Mashhad Dental School were searched for palatal sinus lift. The reason for patients was noticed. Pre- and post-operative radiographs were evaluated.
RESULTS: Ten patients with palatal approach sinus lift were included. Seven patients had previous insufficient sinus lift, one patient had acute palatonasal recess, and two other patients had thick buccal bone.
CONCLUSION: Palatal approach is maxillary open sinus lift is a useful auxiliary in patients with heavy buccal vestibule scar, thick buccal bone, deep palatonasal recess, and for reentry augmentation.

INTRODUCTION

Sinus lift is indicated for vertical augmentation of posterior maxilla for insertion of appropriate length dental implant.[1]

Based on the amount of subantral bone, crestal or lateral approach is indicated.[2]

In sever bone deficiency, open sinus lift through lateral maxillary sinus wall is the first option.[3] Sometimes, this surgery is difficult due to lateral maxillary sinus wall thickness or large diameter alveolar antral artery.[4]

Palatal approach for maxillary sinus membrane elevation is an option with unique indications.

MATERIALS AND METHODS

In a retrospective study, archive files of Dental Implant Department of Mashhad Dental School were searched for palatal sinus lift. Surgical technique was done according to the standard protocol of department. Under local anesthesia, crestal incision with anterior palatal release in between first permanent maxillary premolar and canine was used to get access to palatal bone. With a round surgical bur, osteotomy window was prepared, and Schneiderian membrane was elevated from medial to lateral wall.

Allograft (Cenobone® Tissue Regeneration Corporation, Iran) was used to fill the space between elevated Schneiderian membrane and sinus floor. Reflected palatal flap was sutured back to original position [Figure 1].

Figure 1

(a) Vertical release in between first permanent maxillary premolar and canine, palatal osteotomy and elevation of Schneiderian membrane; (b) bone substitute is used to fill the biologic box; (c) triangular flap is sutured

The reason for a palatal approach to maxillary sinus and demographic information of these patients were noticed. Pre- and post-operative radiographs were evaluated.

RESULTS

Ten patients with palatal approach sinus lift were included in the study. Age ranges were between 20 (a trauma patient) and 68 years. Majority of the patients were female (60%). Seven patients had previous insufficient sinus lift, one patient had acute palatonasal recess, and two other patients had thick buccal bone [Figures 2 and 3]. Schneiderian membrane perforation had occurred during surgery in two patients, both with reentry augmentation. The results were analyzed by the amount of the added postoperative augmentation that was achieved.

Figure 2

Palatal osteotomy. Vertical release is considered between maxillary canine and lateral to avoid soft tissue incision too close to osteotomy site

Figure 3

(a) Insufficient previous sinus lift; (b) postoperative cone-beam computed tomography, after recent augmentation with palatal approach; (c) schematic picture

Angulation of palatonasal recess on the medial wall was considered as acute if it was <90°.[5] A maxillary sinus wall was considered thick if it measured at least 2.3 mm in preoperative cone-beam computed tomography.[6]

DISCUSSION

Maxillary sinus lift is a preprosthetic surgery that was introduced by Tatum and Boyne in 1977–1980.[7] Nowadays, this surgery can be done through three approaches; lateral, crestal, or palatal approach [Figure 4]. In open sinus lift, lateral approach is the most widely used technique. Palatal approach can be used in the cases with a deep palatonasal recess, thick buccal bone, or prominent alveolar antral artery that is located in buccal bony window osteotomy design.[8] Vestibular scar with previous intrasinus manipulation through buccal approach makes reentry for secondary sinus lifting more difficult.[9] Palatal approach to the maxillary sinus for elevating Schneiderian membrane has advantages in these situations.

Figure 4

Three approaches for maxillary sinus lift: Lateral, crestal, and palatal; (a) lateral and palatal approaches for open sinus lift; (b) crestal approach for closed sinus lift in cases with more subantral bone

Blood supply of maxillary sinus is provided through alveolar antral and greatest palatine arteries. The first is located within lateral maxillary sinus bony wall and the second is in the soft tissue of palate.[10] With palatal approach, alveolar antral artery can still supply the augmented bone.

We suggest anterior vertical release in palate because of the added access and visibility. The best location for this release is between first permanent premolar and canine because of the small diameter of the greater palatine artery in this location. Anterior edge of palatal osteotomy window has influential effect on the location of this release. Flap margins should rest on healthy bone, and in the case of anticipated overlap, vertical release should be transferred more anteriorly between canine and lateral. Vertical release in palatal mucosa has not designed to prevent injury to greater palatine artery. Vertical release crosses palatine artery at the right angle. Intentional cutting of this artery in between canine and first premolar almost is not accompanied with pulsatile bleeding. However, if the surgeon confronts with bleeding from this artery, it easily can be controlled by electrocautery or suture ligation. Long envelope flap extending to midline to avoid intentional cutting of greater palatine artery is recommended by some authors. Small distal release is mentioned by others.[1112]

Hematoma formation is possible in edentulous patients that whole palatal mucosa is reflected. Suturing back palatal flap to periosteal remnants in palate or bone suture is strongly recommended in this situation. In partial edentulous patients, deep bites of palatal flap by stiches can prevent hematoma formation. If hematoma happened in palate, accumulated blood should be aspirated.

This surgery is more easily done if the patient has a high palatal vault and thin palatal bone. Facial swelling in this technique is minimal, and risk of emphysema is reduced.[13] This is important in airline travelers and pilots. Edentulous patients can wear dentures without difficulty because of preserved buccal vestibule.[14] Connective tissue flap can easily be obtained for the management of Schneiderian membrane perforation if it is needed [Figure 5].

Figure 5

Posteriorly based connective tissue flap is used to manage sinus membrane perforation during palatal sinus lift

Palatal approach sinus lift is technically more difficult than lateral approach, so it is not recommended for first-time sinus lift if lateral approach is feasible. In our department, majority of cases were reentry augmentations. The difficulty of the procedure increases in thick palatal bone, low palatal vault, and maxillary second molar region. However, this method should be considered as plan B in every maxillary open sinus lift surgery.

CONCLUSION

Palatal approach is maxillary open sinus lift is a useful auxiliary in patients with heavy buccal vestibule scar, thick buccal bone, deep palatonasal recess, and for reentry augmentation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.