A combination of tools and techniques introduced in the 1990s—the dental operating microscope, ultrasonic root-end preparation and biocompatible root-end fillings—resulted in a revision of endodontic procedures termed “periapical microsurgery” that raised the success rate of surgical endodontic therapy from 45% to 60% to more than 90%. Although the literature shows that periapical tissue, the cortical plate and the gingiva experience rapid healing at a histologic level after periapical microsurgery, these reports are based on 2-dimensional imaging, which limits the ability to diagnose 3-dimensional (3-D) changes in structures surrounding the teeth. Thus, studies have focused on healing and reformation of the cortical plate rather than volumetric healing and corresponding site maintenance over time. Inadequate site preservation could make later implant placement problematic.

Crossen et al from the University of North Carolina School of Dentistry used cone-beam computed tomography (CBCT) to establish 4-dimensional (3-D plus time) volumetric healing patterns, focusing on the buccolingual width of the bone and the surface contour of the cortical plane at 1 year after surgery.

They studied 12 patients aged 18 to 65 years at the time of surgery (half of whom were aged >50 years) who had had a CBCT scan performed 3 months before surgery and who had attended a recall examination 1 to 6 years after surgery. Volumetric analysis of the buccal cortical plate showed a median change of –24.9 mm3 over a median of 25 months.


While the loss of nearly 25 mm3 in bone may appear significant, the authors stressed that this loss actually demonstrated the occurrence of little to no regression of the buccal cortical plate. Given that total bone regression was measured over the total area of the surgical site, this loss is equivalent to <0.25 mm linear cortical plate regression averaged over the surgical site surface area. This study showed that healing after periapical microsurgery without grafts occurs with minimal buccal cortical plate regression.

Crossen D, Morelli T, Tyndall DA, Tawil PZ. Periapical microsurgery: a 4-dimensional analysis of healing patterns. J Endod 2019;doi:10.1016/j.joen.2018.11.002.