Piezo surgery: Simplified Extraction of third molars

Originally published in Dental Tribune Latin America

Third molar extraction is one of the most common surgical procedures in dentistry. As with most oral surgeries, it requires thorough clinical and radiographic assessment to develop an optimal treatment plan, thereby reducing and/or avoiding postoperative complications or damage.¹

Piezoelectric technology facilitates third molar extraction by eliminating the need for chisels or rotary instruments during the osteotomy that provides surgical access to the wisdom tooth. This article outlines each necessary step of the procedure.

The complexity of the procedure may vary depending on the tooth’s location, depth, angulation, and the density of the surrounding bone.² One of the most critical and decisive steps in the extraction is the osteotomy performed prior to and concomitant with surgical access to the tooth, for which various instruments may be used, such as chisels, mallets or rotary tools.³

These instruments can be highly invasive, posing a risk of injury to soft and hard tissues and resulting in a significant inflammatory response. Postoperative symptoms often include pain, swelling, and limited mouth opening due to muscle spasm caused by jaw manipulation.⁴

Before proceeding with the removal of third molars, a comprehensive assessment must be conducted, including a precise diagnosis, clear indications, contraindications, and the risks associated with the selected technique.^5,6

The primary indication for third molar extraction is the presence of pathology directly associated with the tooth, such as non-restorable caries, fractures, cysts, tumours, or, in some cases, untreatable pericoronitis. Extraction may also be indicated due to lesions affecting adjacent teeth – such as proximal carious lesions, root resorptions, or active periodontal disease. Additionally, third molars may be removed if they pose an obstacle in planned orthodontic, prosthetic, or complex surgical treatments.⁷

Once the diagnosis has been confirmed, several factors must be considered when planning the extraction technique for a third molar:

High-speed handpieces are commonly used for the removal of hard tissue around partially or fully impacted third molars. Morphological analyses have shown that rotary instruments produce irregular bone surfaces and marginal osteonecrosis due to the high temperatures generated during bone removal.⁸

In contrast, piezoelectric instruments perform micrometric cuts, removing only a minimal amount of bone and significantly reducing the risk of marginal thermonecrosis compared to conventional rotary burs.⁹ The micrometric movements allow for greater cutting precision and tactile control, while eliminating excessive vibrations typically associated with rotary instruments.¹⁰
 
Its oscillation amplitude ranges from 60–200 µm horizontally and 20–60 µm vertically, which is significantly lower than that of oscillating micro saws, thus enabling highly precise and safe osteotomies. Additionally, the ultrasonic vibrations generated by the instrument break the irrigation fluid into very fine particles (a phenomenon known as cavitation effect), producing a hemostatic effect and thereby reducing blood loss. This ensures a clear and unobstructed view of the surgical field.^11,12

Jian Q. et al.¹³ reported that although patients undergoing piezo surgery experienced longer surgical times, they exhibited reduced postoperative inflammation, suggesting that piezo surgery is a promising alternative for the extraction of impacted third molars. Rullo et al.¹⁴, however, associated longer surgical durations with increased postoperative pain, particularly due to the slower, micrometric cutting action of the piezoelectric device.

It should be noted that postoperative pain following third molar extraction also depends on several other factors, including the extent of flap elevation, smoking habits, oral hygiene status, patient age, anxiety levels, and a history of pericoronitis.

Figure 1. Third molar position: Third molar in vertical position (a). Third molar in mesioangular position (b). Third molar in horizontal position (c).

The procedure begins with the administration of a mandibular nerve block to anaesthetise the inferior alveolar nerve and its branches. Subsequently, surgical access is planned according to the position of the third molar to be extracted.For didactic purposes, the extraction of the molar depicted in Figure 1 (c) will be described:

a horizontal incision is made in the retromolar area, extending distally to the second molar. This is followed by an intrasulcular incision continuing mesially along the second molar, and completed with a full-thickness vertical incision extending to the mucogingival junction (Figure 2).

Figure 2. Incision design for access to the third molar.

Figure 3. Full-thickness flap elevation for access to the third molar.

Figure 4. Demarcation of the osteotomy area using straight and/or angled piezo instruments for bone surgery (e.g. the B1, B2R or B2L by W&H) at the occlusal level. Frontal view (a). Occlusal view (b).

Figure 5. Fracture and removal of the bone fragment from the coronal occlusal portion.

Figure 6. Demarcation and fracture of the osteotomy area at the buccal level using a straight and/or angled serrated piezo instrument (e.g. B1, B2R or B2L by W&H).

Figure 7. Removal of the buccal fragment.

Figure 8. Odontosection using a high-speed bur and/or piezoelectric instrument (e.g. B6 or B7 by W&H). Subsequently, the pericoronal space is widened with the piezoelectric periotome (EX1 or EX2 by W&H) to facilitate tooth extraction.

Figure 9. Extraction of the coronal portion of the third molar.

Figure 10. Mesial traction of the remaining tooth fragment using straight elevators.

Figure 11. Removal of the residual root fragment of the third molar.

Figure 12. Removal of the pericoronal tissue and inspection of the extraction socket.

Figure 13. Flap repositioning and suturing.