Gregory M. Kusner, DDS is a dentist specializing in endodontics who maintains a Carlsbad practice address on La Golondrina Street in the La Costa area near the Omni La Costa Resort. Endodontic focus means the practice concentrates on root-canal therapy, retreatment of failed prior cases, and apicoectomy surgery, a referral-driven specialty that overlaps with the microsurgical endodontic work performed at Merchant Endodontics along the El Camino Real corridor. Root-canal procedures use electronic apex locators to determine precise working length before nickel-titanium rotary instrumentation shapes and cleans the canal system. Obturation with warm vertical condensation of gutta percha seals each canal to the radiographic apex, reducing the risk of post-treatment reinfection. Patients presenting with cracked-tooth syndrome or referred temporomandibular pain sometimes coordinate diagnosis between endodontic and musculoskeletal providers such as La Costa Chiropractic & Wellness to distinguish pulpal pathology from myofascial referred pain. The most technically demanding cases involve calcified canals requiring operating-microscope magnification and ultrasonically activated instruments to negotiate mineralized obstructions without perforating the root wall.