AAE on cracked teeth and vertical root fractures (2022): not every cracked tooth needs a root canal, every one of them needs a crown

What it says#

There is no AAE position statement on cracked teeth. What the AAE has is a clinical resource, the 2022 edition of Colleagues for Excellence, written by Keith V. Krell, which updates the association's 2008 issue on the same subject, and a companion classification table the AAE has hosted since 2008. Together they are what a general dentist should be reading.

The classification comes first, because it decides everything after. The AAE's table sorts longitudinal tooth fractures into five types by location, direction, origin, symptoms, signs, identification, treatment and prognosis. A craze line is enamel only, runs occlusogingival, is asymptomatic, needs no treatment beyond esthetics, and has a very good prognosis. A fractured cusp involves the crown and the cervical margin of the root, runs mesiodistal and faciolingual, gives sharp pain on mastication and with cold, is treated by removing the cusp and restoring, and also has a very good prognosis. A cracked tooth runs mesiodistal from the occlusal surface, may stay in the crown or extend to the root at a depth you cannot know, gives highly variable symptoms, is identified by biting and by removing the restoration, is treated with root canal treatment where the pulpal and periapical diagnosis calls for it plus full cuspal coverage, and the table calls its prognosis always questionable to poor. A split tooth reaches crown and root with extension to the proximal surfaces, shows separable segments and a periodontal abscess, requires that one segment be removed and the rest restored or the tooth extracted, and is hopeless if you try to keep it intact, variable if the segment comes out. A vertical root fracture is in the root only, runs faciolingual, gives none to slight symptoms, is confirmed by reflecting a flap and transilluminating, and is hopeless for the fractured root.

The vocabulary has since been redrawn. The AAE formed a Special Committee on Cracked Tooth Initiatives in May 2014 because the definitions in the 2012 glossary, the 2008 Colleagues issue and the International Association of Dental Traumatology did not agree with one another and overlapped. The 2015-2016 AAE Board approved new definitions that now sit in the 2020 glossary: infraction, which is the craze line, defined as a crack of the enamel without loss of tooth structure; cracked tooth, a thin surface disruption of enamel and dentin, and possibly cementum, of unknown depth or extension; fracture, a disruption assumed to be of greater depth than a crack; root fracture; longitudinal fracture, a root fracture in the axial plane; vertical root fracture, where the fractured segments are incompletely separated; and split root, where they are completely separated. Crown infraction was removed. Abfraction got its own definition. The practical consequence is that the older table's five headings and the current glossary terms are not a one-to-one map, and a chart note should use the glossary wording.

Diagnosis is the longest section. It starts with history, and the questions are specific: does the pain occur on biting down or on release, are fillings fracturing or dislodging, are there brief episodes of cold sensitivity, is there mobility. The objective exam expects a surgical operating microscope, because the naked eye often misses the subtle details, plus transillumination from multiple directions, dye staining, and flexure seen under magnification. The listed tests are soft tissue exam for swelling or sinus tracts, percussion, palpation, biting tests with each cusp tested separately, cold and electric pulp testing, periodontal probing with flexible plastic probes, restoration removal where needed, transillumination, dye staining, surgical assessment, and a radiographic exam with both periapical films and CBCT as routine. The AAE's 2016 methodology committee listed the findings highly suggestive of a crack or fracture: triggered biting pain, swelling, one or more sinus tracts, percussion sensitivity with mobility, a root crack next to a deep probing, probings greater than 6 mm, a visible fracture or a J-shaped radiolucency on a conventional film, a visible fracture on small field of view CBCT, and bone loss at an isolated periodontal defect. Small field of view CBCT helps find isolated bone loss, but flap reflection with a microscope is still called the gold standard.

Then the outcomes, and this is the part that changes treatment planning. The issue is emphatic that a cracked tooth is not necessarily hopeless as was thought earlier, and that the earlier a crack is found the better the survival, especially if crowned early. In two studies, cracked teeth with reversible pulpitis and normal apices that were crowned immediately had an 80% chance of never needing root canal treatment. The Iowa Staging Index grades what happens when root canal treatment is needed, on three factors: the depth of the probing at the crack, the location of the crack, and whether there is apical pathosis. Stage 1, probing under 5 mm, a mesial marginal ridge crack, no apical pathosis, had 93% success and survival reported as high as 97%. Stage 2, the same but with a distal marginal ridge crack, 84%. Stage 3, adding apical pathosis, 69%. Stage 4, probing over 5 mm with any marginal ridge crack, 41%. Two meta-analyses and a large retrospective study agreed that probings of 5 mm or more at a crack cut survival and that timely crown placement improves it; root canal treatment of cracked teeth is reported at 84% survival at 60 months.

On vertical root fractures the position has softened only for molars. A single-rooted tooth with a vertical root fracture will generally need to be extracted. On a multi-rooted tooth, the issue argues for root resection, amputation or hemisection over extraction and an implant, citing 92% survival for root amputation over 12 years and 79% to 91% for hemisection over 7 to 30 years, and a comparison in which single-tooth implant patients had four times as many appointments and more than twice the expense as patients who had a root canal and a crown, with the same success rate.

Who it applies to#

Every general dentist, because the first three types are found and treated in general practice and the last two are found there and referred. The AAE's framing is that cracked teeth and vertical root fractures now belong in almost every differential diagnosis of tooth pain, on the strength of its own survey: 49% of 941 endodontists had seen an increase compared with previous decades, before the pandemic, and the increase has continued since.

It does not cover fractures from acute trauma, which follow the IADT guidelines covered separately here. And the AAE's only formal cracked tooth position document, Guidelines for the Methodology of Cracked Tooth Studies, is aimed at researchers: it tells institutions, practice-based research networks and group practices how to design a prevalence study so the data can be pooled later. It is worth knowing it exists so you do not cite it as clinical guidance.

What changed#

Three things since the 2008 issue. The vocabulary was rewritten and now lives in the 2020 glossary. CBCT moved from optional to routine in the diagnostic workup, with isolated bone loss next to a root surface and loss of cortical bone read as indirect signs. And the prognosis conversation acquired numbers, so a patient can be told 93% or 41% rather than "we will see."

My own view: the sentence that should change behavior in a general office is not about endodontics at all. It is that all cracked teeth require a crown. The common failure I see is a cracked tooth diagnosed at a hygiene visit, treated with an occlusal adjustment and a wait-and-see note, and crowned two years later at Stage 4 instead of Stage 1. The diagnosis is cheap; the delay is what costs the tooth.

Where the source is#

The link under the title is the AAE's 2022 edition of ENDODONTICS: Colleagues for Excellence, Cracked Teeth and Vertical Root Fractures: A New Look at a Growing Problem, eight pages, copyright 2022 American Association of Endodontists, authored by Keith V. Krell with four named reviewers; it downloaded and was read in full, references included. The five-type classification table is the AAE's Summer 2008 bonus material A, Classification of Longitudinal Tooth Fractures, a two-page PDF on the same site, which carries a line saying it is reprinted with permission from Torabinejad and Walton, Principles and Practice of Endodontics, fourth edition, pages 108 to 128; that table was also read in full. The Summer 2008 Colleagues issue and the 14-page Guidelines for the Methodology of Cracked Tooth Studies, developed by a special committee chaired by Shimon Friedman, are both free PDFs on aae.org and were opened and read. Note that aae.org answers automated download tools with a 403, so all four were fetched through a browser-equivalent request. The Iowa Staging Index figures, the 80% figure for immediately crowned teeth and the amputation and hemisection survival rates are as the 2022 issue reports them from its cited literature; the underlying papers were not read for this entry.