Evaluation of Extraction Sites for Evidence of Retained Tooth Roots and Periapical Pathology*
The objective of this retrospective clinical study was to determine the frequency and pathogenicity of unintentional retained tooth root fragments after extraction of the maxillary fourth premolar (108 and 208) and mandibular first molar teeth (309 and 409) in 74 canine and 42 feline client-owned patients. Radiographs of client-owned animals with historical evidence of extraction of teeth 309 and 409 were reviewed. All patients had dental extraction(s) for clinical reasons, and all extractions were deemed successful by the practitioners. Extraction sites were radiographed to identify tooth root fragments and pathology. Twenty-five canine and 25 feline patients that had extractions utilizing preoperative and postoperative radiography were also included. Sixty-one of 74 canine patients (82.4%; P < 0.0001) and 39 of 42 feline patients (92.8%; P < 0.0001) had evidence of retained tooth root fragments. In total, 100 of 116 cases (86.4%; P < 0.0001) had retained tooth root fragments, and periapical pathology was found in 66 of 116 (56.8%; P = 0.000000743) radiographs, including 39 of 74 canine cases (52.7%; P = 0.00002765) and 27 of 42 feline cases (64.3%; P = 0.01589). The control group had no evidence of retained root fragments. Further veterinary dental training and routine use of pre- and postoperative dental radiology are recommended.
Introduction
Exodontia is one of the most common procedures in general and referral veterinary dental practice. The prevalence of periodontal disease and poor preventive care provided to veterinary patients results in teeth commonly becoming nonvital. Current veterinary curricula often include either little or no training in current techniques of surgical exodontia and dental radiology, and yet tooth extractions are performed by > 90% of veterinarians in their first year in practice.1 It is more common for general practice veterinary hospitals to have ultrasonography rather than dental radiography on site, yet 85% of animals have periodontal disease.2,3 The purpose of this investigation was to examine the frequency and consequences of retained tooth root fragments in a group of patients deemed to have undergone successful extraction attempts.
Indications for exodontia include complicated crown fractures, nonvital teeth, significant bone loss resulting from periodontal disease, root fractures, traumatic malocclusions, severe wear, persistent deciduous teeth, feline tooth resorption, caries, and relief of inflammatory conditions, such as chronic ulcerative paradental stomatitis and lymphoplasmacytic stomatitis/glossitis/faucitis complex (now called caudal stomatitis).2,4 Exodontia is often the treatment of choice due to insufficient operator skill to accomplish more advanced tooth-saving techniques, such as endodontia, orthodontia, and periodontal surgery.2 Even when a practitioner has advanced dental skills, exodontia is often necessary.
Large multirooted teeth, such as right maxillary fourth premolar (108), left maxillary fourth premolar (208), left mandibular first molar (309), and right mandibular first molar (409), generally require surgical extraction, including reflecting a mucoperiosteal flap and sectioning of teeth into single-rooted segments.1,4–8 Those procedures are usually followed by removal of buccal bone to facilitate nontraumatic extraction of the root segments.1,4–8 Often, those teeth will have significant aberrations of root tip anatomy to accommodate the variations in alveolar anatomy.9–11 The mandibular first molar mesial root is often deflected by its proximity to the mandibular ventral cortex, and the roots of 108 and 208 can be deflected by brachycephalic anatomy and tooth crowding.10 Finally, mandibular first molars commonly have a developmental groove on the mesial root that further complicates extraction attempts.10–13 Many teeth have extra roots, requiring a surgical approach to completely extract.10 Preoperative radiology is used to facilitate clinical treatment planning and surgical approach for those anatomic anomalies.2,6 Postoperative radiographs identify retained tooth root fragments and document complete extraction.4–8
Materials and Methods
Review of medical records of clients referred to the Southern California Veterinary Dental Specialties identified 116 records (74 canine and 42 feline) with specific historical details. They were of various breeds, ages, and sexes. Reference to specifically named extractions of 108, 208, 309, and 409 was required for inclusion in this study. Cases were excluded if the animal was referred for known incomplete extraction, if there was crown amputation with intentional root retention, the roots had significant replacement resorption, or if there was not a specific reference to a named tooth (i.e., if the record included a reference to extraction of a molar tooth but no tooth was named). Finally, if there were any clinical signs of the retained roots (i.e., visible roots in the mouth, swelling, fistula), the patient was excluded from the study.
Patients were presented to the dental referral service for oral therapy (typically, with an additional fractured tooth) that required anesthesia, examination, and radiography. The animals were examined preoperatively, had appropriate preoperative evaluations, and were anesthetized. Perioperative oral examination and charting was performed. The area of extraction was radiographeda,b, and reviewed for evidence of complete extraction, the presence and number of retained tooth root fragments was noted, and any pathology was recorded. Intraoral dental radiographs were made using conventional bisecting angle and parallel techniques and recorded using digital sensors and softwarec,d,e.1,4,10–15
Radiographs of extraction sites were evaluated for presence of periapical pathology. Periapical pathology included severe osseous ankylosis, sclerosis, and alveolar bone loss that was most often either periapical or periradicular lucency as shown in Figures 1–4.6,15 The presence of radiographic changes was recorded.
Citation: Journal of the American Animal Hospital Association 50, 2; 10.5326/JAAHA-MS-5977
Citation: Journal of the American Animal Hospital Association 50, 2; 10.5326/JAAHA-MS-5977
Citation: Journal of the American Animal Hospital Association 50, 2; 10.5326/JAAHA-MS-5977
Citation: Journal of the American Animal Hospital Association 50, 2; 10.5326/JAAHA-MS-5977
A control group was established using an initial date of January 1, 2008 that included the first 25 canine and 25 feline cases of exodontic procedures involving carnasial teeth (108, 208, 309, 409). Those cases were all recruited from a general practice that utilized pre- and postoperative oral radiography.3–6 No tooth root fragments were noted on examination of postoperative radiographs in the control group (Figures 5, 6).
Citation: Journal of the American Animal Hospital Association 50, 2; 10.5326/JAAHA-MS-5977
Citation: Journal of the American Animal Hospital Association 50, 2; 10.5326/JAAHA-MS-5977
Statistical Analysis
Patient details were recorded and P values < 0.05 were considered significant. A χ2 test for independence was performedf. The resulting P value was .0000001, indicating association between the variables.
Results
In total, 74 canine and 42 feline extraction sites were examined radiographically for the presence of retained tooth root fragments and periapical pathology. Of those, 61 of 74 canine cases (82.4%, P < 0.0001) showed evidence of retained tooth root. Pathology was identified in 39 of 74 cases (52.7%, P = 0.00002765). When the specific cases with retained roots were evaluated for pathology, 39 of 61 cases (61.9%, P < 0.0001) showed evidence of disease. There was no periapical pathology noted in cases of complete extraction. In the feline cases, 39 of 42 cats showed evidence of retained tooth roots (92.8%, P < 0.00001). Twenty-seven had pathology at the apical area (64.3%, P = 0.01589), and 27 of 39 cases with retained roots showed pathology at the apical area (69.2%, P < 0.001). There were no cases of pathology with complete extraction. The control group of canine and feline patients showed complete extraction with no periapical pathology at the extraction sites.
When all cases were combined, tooth fragments were identified in 100 of 116 animals (86.2%, P < 0.00001). Sixty-six of 116 animals showed pathology at the periapical area (56.8%, P = 0.000000743). There was pathology at the apical area in 66 of 100 animals with evidence of retained tooth root fragments (66%, P < 0.001).
Discussion
In this clinical study, cases of confirmed, complete extractions occurred at a very low rate. The data showed a significant failure rate of complete exodontia. Those retained tooth root segments caused periapical pathology 66% of the time, making complete exodontia of infected teeth a necessity, not simply a goal. The majority of patients in the current study did not receive postoperative radiographs following extraction; however, in two of the canine cases with retained roots, the veterinarian did take and interpret postoperative images. In both cases, the veterinarian documented complete extraction; however, the retained roots were not only easily visualized on subsequent images taken at the referral hospital, but plainly visible on the radiographs sent from the original hospital.
This study’s aim was to present a very controlled population of animals. Selection of those cases required specific reference to an extraction attempt that was made for particular teeth and cases in which the extraction was deemed successful by the referring veterinarian. Moreover, it was important to eliminate the possibility of either traumatic coronal fracture or intentional root retention causing the retained root fragments.
The purpose of the second, and possibly most important portion of this study, was to evaluate the probability of retained tooth root fragments representing a practical risk of pathology to the patient. If this study was performed using cone-beam computed tomography (CT), the occurrence of pathology would likely be even higher.16–19 Because veterinary patients are known to be stoic when it comes to oral pain, some patients with no radiographic evidence of disease may in fact be painful.5 Due to the high probability of retained tooth root fragments causing pathology (63.9% in canines and 69.2% in felines), as well as the above-mentioned information, it is critical to remove all tooth root fragments.16–19 One previous study showed cysts with squamous cell linings (presumably early odontogenic cyst formation) were recorded with nearly the frequency of histologic abscess formation.20 Either odontogenic or dentigerous cysts will often place surrounding bone at risk for osseous resorption and eventual destabilization of the jaw.21,22
Twenty-two of 61 canine retained roots and 12 of 37 feline retained roots did not show radiographic evidence of pathology. That may have been a result of either radiographic resolution failing to display pathology or lack of pathology. one study published in 1974 suggested intentional retention of nondiseased, nonvital tooth root segments in dogs would result in little histopathologic changes.20 Another study included experimentally extracting healthy teeth in beagles with no history of periodontal disease or indications for exodontia. Experimentally rendering teeth 309 and 409 in beagles nonvital by extirpating pulp and submerging the remaining nonvital roots 2 mm subgingivally resulted in abscess formation coronally in 3 of 8 dogs and cysts lined with squamous cells were noted in an additional 3 dogs.21 Further investigations involving the use of cone-beam CT and histologic evaluation of retained root sites would be helpful in elucidating the pathophysiology of retained roots.
A current trend in human dentistry to intentionally retain tooth root segments in impacted mandibular third molar (wisdom) teeth is under evaluation.23 That technique, involving coronectomy of impacted mandibular third molars 17 and 32, differs from veterinary patients in that the teeth chosen for that technique are impacted, sterile, and will be followed closely for signs of either root translation or pathology, preferably with cone-beam CT.23 Previous investigations in veterinary dentistry were under similar circumstances, with healthy teeth undergoing coronectomy under a controlled environment had similar results.20,21 Veterinary patients have an evolutionarily derived stoicism and are less likely than humans to demonstrate discomfort.24
In a 1995 study evaluating teeth affected by type II tooth resorption treated with crown amputation and intentional root retention, 102 roots from 59 teeth in 29 cats showed that, under controlled circumstances, root retention is not only advisable, but preferable, than complete extraction.25 In that study, cases were carefully chosen to exhibit significant type II tooth resorption (erosion into pulp), be radiographically free of evidence of periodontal and endodontic disease, had no probing defects, had no mobility, and were free from retroviral infection and evidence of caudal stomatitis.25 Teeth were treated with crown amputation and intentional root retention and monitored for 5–36 mo. Overall, 100 roots resorbed uneventfully, with 1 root remaining radiographically visible, without evidence of pathology. Further, one cat subsequently developed caudal stomatitis and required extraction of the root in question as well as a full-mouth exodontia.25 The areas treated with crown amputation and intentional root retention showed less loss of crestal bone than complete extraction sites. The 1995 study demonstrated that crown amputation with intentional root retention was both safe and effective, but only under very strict criteria.25
Studies in human dentistry show that only 10% of attempted exodontias result in retained tooth roots. There have been no studies in veterinary dentistry reviewing the success rate of routine exodontias.26
Evaluation of the radiographs for evidence of periapical pathology was significant in this study because the importance of complete exodontia would be significantly diminished if retention of tooth root fragments was thought to be nonpathologic. Radiographic evidence of periapical pathology is indicative of infection of the root fragment resulting in either granuloma or abscess formation.27–31
The inability to control for age, sex, breed, surgical techniques, or length of time postextraction were all limits of this current investigation. A large-scale investigation into the histopathologic changes of retained tooth root fragments would provide illumination regarding the mechanics of subgingival retention of nonvital tooth root segments. The frequency of surgical failure may be quite different for either single rooted teeth or smaller multirooted teeth.
An important note is that that this study was performed in California where the practice act allows licensed technicians to perform extractions. That fact may partially explain the tremendous number of extraction failures seen in this study. Furthermore, this study could not be controlled by operator because the medical records often had no mention of who performed the dental extractions. An additional study in a state where technicians are not allowed to perform extractions would be enlightening.
This investigation showed the need for further investigation. As of 2003, nine states allowed technicians to perform extractions. In general, practice acts nationwide state only “dental extraction” without further definition of either simple or closed extraction (no incision of gingival margin) or surgical extraction (incision of gingiva with removal of buccal bone). Following discussions with various veterinary medical boards, the “intent” of the law was always closed extraction; however, the “letter” of the law is ambiguous. Regardless of the semantics, gingival flaps, sectioning, and buccal cortical bone removal are almost always required for extractions of carnassial teeth. Those techniques are beyond what should be permissible for technicians because technicians are not allowed to “alter the patient.” However, the majority of extractions in this study were likely performed by technicians. The American Veterinary Dental College position statement reads that only licensed veterinarians perform those procedures.4,32 The high frequency of postoperative pathology (66%) again shows the necessity of those surgical techniques being completed only by competent and trained veterinarians.
Finally, this study underscores the importance of dental radiology in veterinary dentistry. Many of those retained roots could have been diagnosed and treated promptly if postoperative radiographs had been taken and properly interpreted. The fact that two cases had postoperative radiographs that were misdiagnosed as complete extraction proves that more training in dental radiographic interpretation is also necessary. It is the authors’ hope that this study will result in superior extraction techniques and better patient care.
Conclusion
Retained tooth root fragments in this group of patients having undergone extraction attempts deemed successful was frequent. The presence of these fragments resulted in a high rate of pathology.
Radiograph showing retained root pathology in a dog. Note the retained root (outlined arrows) and periapical lucency (solid arrow) surrounding the root fragments.
Radiograph showing retained root fragments in a dog. The arrow is pointing at the mesial root of 309. Note the mesial root of 309 completely within the mandibular canal. Further, there is significant tooth resorption on the distal root of 308 and alveolar bone loss on the second molar (310).
Radiograph showing retained root pathology in a cat. Note the vertical bone loss at the mesial ridge and periapical lucency (solid arrow) evident at distal root of 309.
Radiograph showing retained root pathology in a cat. Note the large periapical lucencies (solid arrows) at the retained root fragments (outlined arrows) of 104, 107, and 108.
Exemplar pre- and postoperative radiographs of a successful extraction of 408 and 409 in a cat.
Exemplar pre- and postoperative radiographs of a successful extraction of 207–209 in a dog.
Contributor Notes
Throughout this document, the modified Triadan system was used to identify teeth (available at: www.avdc.org. Accessed December 14, 2013).
