Simultaneous Perio-endo Surgery with ER:YAG Laser and Bone Xenograft. A Case Report

Periodontally affected teeth with periapical lesion indicated for periapical surgery have a poor prognosis. Using Er:YAG lasers to perform simultaneous surgery on both defects may increase their survival rate. Preparing a retrograde cavity on affected teeth and obturating it is still a matter of debate among clinicians. The purpose of this case report was to describe the simultaneous use of Erbium-doped Yttrium Aluminium Garnet Er:YAG (2,940 nm) laser in the treatment of periapical granuloma and infraossal defect and the achieved results. The Er:YAG laser was used to perform flap dissection, granulation tissue removal, osteotomy and root-end resection except for initial flap incision and reflection. The cystic cavity was filled with Bio-Oss Collagen® xenograft. Results were followed up for 18 months with the help of radiographic orthopantomographic images. The outcome of this clinical case indicates that the use of Er:YAG laser could be considered a suitable method to perform simultaneous periodontal and endodontic surgery.


INTRODUCTION
About 15% -30% of apical lesions do not regress after nonsurgical endodontic treatment and periapical surgery is indicated. Its purpose is to remove all pathological tissues, seal the root canal and regenerate the periodontium. Surgery faces a few issues: choice of access flap, size of ostectomy, length of root resection, retrograde preparation, micro-permeability, material for retrograde obturation, periodontal bone loss. They complicate the procedure, increase mobility and worsen prognosis (Kim S, Kratchman S, 2006). Major problem is the difficult access for root observation and preparation, haemostasis, placement of obturating material. The classical rotary technique is more damaging in periodontally affected teeth due to bur vibration destabilising the tooth. It leads to lower clinical survival. 1 Lasers may enhance periapical surgery 2,3 and periodontal therapy 4 , by requiring less tools, 5 less time, providing surgical field disinfection, sealing of tubules 1,6-10 , enhanced bone healing, and a shorter recovery period. [11][12][13] We present a case with a periapical cyst and multiple infarossal defects simultaneously treated with erbium doped yttrium aluminium garnet-Er:YAG laser.  (Fig. 3). Decision was made to continue treat-     (Fig. 4).

CASE REPORT
Full thickness flap with no vertical incisions was reflected mainly on the buccal from the distal gingival margin of tooth 15 up to the distal of 25 to allow access to infraossal defects and periapical lesion of 12. Treatment protocol is similar to that described by Reyhanian A, et al. (2008). Laser is regularly calibrated and metered by the manufacturer. During the surgery, laser was used in a pulse mode. Impulses were 100-200 µs in width. Spot size was dependent on the sapphire Folia Medica I 2020 I Vol. 62 I No. 3     (Fig. 5).
Calculus was removed with Piezon Master 400 ® , tip P3 and hand Gracey Curretes. Initially, we treated the inner surface of the flap and all infraossal defects by removing granulation tissue with flat cylindrical tip for ablation (non-contact mode; 400 mJ/20 Hz; 8 W; 0.8×14 mm tip; water level 4) (Fig. 6).
In non-contact mode, the tip was 1-2 mm away from the tissue. Cyst had resorbed vestibular cortical plate but not enough for straight access so the cavity was widened, ostectomy (non-contact mode; 300 mJ/25 Hz; 7.5 W; 1.3×19 mm tip; water level 8) (Fig. 7). 11 The cyst was dissected from the walls and removed with tweezers and cavity ablated.  X-ray observations at 6 months showed complete resolution and fill up of both bone defects (Fig. 8) and physiological PPD (Fig. 9). 75 (Fig. 2). After a period of 6 months density was 40-114 isodensity dots/ average 29 (Fig.  10); densitometric analysis average 62. Eighteen months later density was 49-156 isodensity dots/ average 81; densitometric analysis average 72 (Fig. 11) evaluated with Kodak Dental Imaging Software®.

Initially, the density in the range of cystic cavity on the OPT image was 30-129 isodensity units/ average 26; densitometric analysis average
Eighteen months after surgery, tooth 12 is still in the patient's mouth with a first degree of mobility according to Miller index of mobility (Fig. 12). Soft tissues healed with minimal scarring and recession, and there was complete bone fill of infraossal and periapical bone defects (Fig. 13).

DISCUSSION
Lasers can be used for every step of surgery. 2,4,5,7,[11][12][13][14][15] Results are monitored for a period of 90 13 , 180 5 , days up to 3 7 to 10 years and show preservation of treated teeth. Er:YAG lasers have less thermal effects 10 , cause no carbonisation, 15 improve sealing between dentin and epoxy sealer 10 , have fewer cracks, chippings, and burning effects when compared to Nd:YAG, CO 2 lasers 1,7-9 or ultrasonic tips. 2 Lasers produce smoother resected root surfaces 1,6 , less vibration -1.5 W power 11 , and less chipping compared to diamond burs 4 but are inferior to carbide burs. 6 Some authors believe that the use of burs is the best way to perform periapical surgery 5 because it leads to less inflammation 13 , has more bone fill, and takes less time. 3 Epoxy sealers lased with Er:YAG have less apical micro-leakage, compared to   zinc oxide eugenol (ZEO) cements and root end prepared with ultrasonic tips. Some authors find no difference in permeability between roots resected with burs or lasers. Different power modes 6 , especially higher 400 mJ 8,9 , lead to different dentin sealing ability, different methylene blue permeability, irrespective of retrograde cavity materials like mineral trioxide aggregate (MTA), super ethoxy benzoic acid (SuperEBA), intermediate restorative material (IRM). Results are better, compared to retrograde cavities prepared with ultrasonic tips. We believe that laser incision is not beneficial 15 and leads to shrinkage, unlike other researchers who find less pain and inflammation. 2,5 Use of microscope could increase treatment time 11 , cause less inflammation and have more predictable results 15 compared to standard rotary technique. Er:YAG lasers bone ablation led to defect resolution, which may be due to stimulated platelet derived growth factor (PDGF) secretion 11,12 , which is supported and achieved by some authors 8,11 but not all agree. 8,12 Bio-Oss collagen ® was used as a grafting material due to the size of the lesion ≥10 mm which may have improved results with or without a membrane. Taschiery et al. (2007), however, believe that there is no beneficial effect from grafts compared to cases without graft or a membrane. 14 Von Arx T, Cochran DL (2001) believe that using collagen membranes alone will lead to significantly better results. Using lasers leads to greater accuracy and reduces the tools needed for periapical surgery. This is contrary to the opinion of other researchers who find less control over depth of preparation. Bone healing and fill shows that enough disinfection and sealing of the root tip and infraossal defect has been achieved.

CONCLUSION
Based on previous research and the case described, we believe that simultaneous periodontal and endodontic surgery performed with Er:YAG laser with xenograft and without retrograde filling, is suitable for similar cases. Further randomised controlled clinical studies are needed to confirm stable and predictable results.