Accepted Manuscript What are the types and frequencies of complications associated with mandibular third molar coronectomy? A follow-up study Giuseppe Monaco, DMD, Giselle De Santis, DMD, Giuseppe Pulpito, DMD, Maria Rosaria Antonella Gatto, PhD, Elisabetta Vignudelli, PhD student, Claudio Marchetti, MD, DDS PII:

S0278-2391(15)00071-3

DOI:

10.1016/j.joms.2015.01.016

Reference:

YJOMS 56634

To appear in:

Journal of Oral and Maxillofacial Surgery

Received Date: 14 May 2014 Revised Date:

19 January 2015

Accepted Date: 20 January 2015

Please cite this article as: Monaco G, De Santis G, Pulpito G, Gatto MRA, Vignudelli E, Marchetti C, What are the types and frequencies of complications associated with mandibular third molar coronectomy? A follow-up study, Journal of Oral and Maxillofacial Surgery (2015), doi: 10.1016/ j.joms.2015.01.016. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT

What are the types and frequencies of complications associated with mandibular third molar coronectomy? A follow-up study

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Giuseppe Monaco, DMD; Giselle De Santis, DMD; Giuseppe Pulpito, DMD; Maria Rosaria Antonella Gatto, PhD; Elisabetta Vignudelli, PhD student, Claudio Marchetti, MD, DDS

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Giuseppe Monaco, DMD – Visiting Professor- Department of Oral and Dental Science, University of Bologna, Italy – e-mail: [email protected]

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Giselle de Santis, DMD- Resident – Department of Oral and Dental Science, University of Bologna, Italy – e-mail: [email protected] Giuseppe Pulpito, DMD-Resident – Department of Oral and Dental Science, University of Bologna, Italy – e-mail: [email protected] Maria Rosaria Antonella Gatto, -PhD – Researcher-Department of Oral and Dental Science, University of Bologna, Italy – e-mail: [email protected]

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Elisabetta Vignudelli, - PhD student- Department of Oral and Dental Science, University of Bologna, Italy – e-mail: [email protected]

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Claudio Marchetti, Md, DDS-Professor and Head- Department of Oral and Dental Science, University of Bologna, Italy – e-mail: [email protected]

Corresponding Author:

Dr. Giuseppe Monaco (e-mail:[email protected]) Department of Oral and Dental Science, University of Bologna, Italy Via San Vitale 59, 40125 Bologna, Italy Tel.: 0039-051-2088155 Fax: 0039-051-225208(Telephone, fax and e-mail can be published)

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Abstract Purpose: Coronectomy has been proposed for impacted third molars in close proximity to the inferior alveolar nerve (IAN) to avoid neurological injury. We investigated

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immediate (up to 1 month) and late (between the 2nd and 36th months) postoperative complications.

Methods: A prospective cohort study was performed on healthy patients treated in the Oral Surgery Department at the Dental Clinic, University of Bologna. The predictor

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variables examined were experience of the surgeon (< 10 years vs. ≥ 10 years), length of surgery, type of mandibular third molar inclusion, and patient age. To assess the rate of postoperative complications, outcome variables were neurological injuries,

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postoperative pain, swelling, fever, alveolitis, pulpitis, and root exposure. The success rate and need for a second surgery were also investigated. Univariate and bivariate descriptive statistics, Kaplan-Meier analysis, and Cox hazards modeling were performed to evaluate the variables.

Results: The study involved 94 healthy patients, who had 116 third mandibular molars

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treated with coronectomies. The patients’ mean age was 28.99 ± 8.9 (range, 17–56) years, and there were 37 males and 57 females. During the 3-year follow-up period, 28 patients (29 coronectomies) dropped out of the study. There was no case of neurological injury to the inferior alveolar nerve or to the lingual nerve (LN). In total, 30

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complications were observed: 25 immediate (up to 1 month) and 5 late (between the second and twelfth months). Surgeons with < 10 years training exposed patients to a greater risk of complications (hazard ratio = 2.069, 95% clearance [CI] = 1.004-4.263).

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An overall success rate of 74% at 6 months was estimated, and a second surgery was needed in 6% of cases. Of the retained roots analyzed, 80% showed postoperative root migration.

Conclusions: In this study, coronectomy of mandibular third molars did not result in temporary or permanent injury to the IAN or LN. Coronectomy showed a low rate of postoperative complications. However, within the first year, a second surgery was needed in 6% of coronectomies to remove migrated root fragments. Additional studies with larger patient samples are recommended to further investigate differences in postoperative complications in relation to patient age.

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Introduction Extraction of impacted mandibular third molars in close proximity to the inferior alveolar nerve (IAN) can result in temporary or permanent neurologic injury. This

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postoperative complication is more frequent in older patients (≥ 40 years) (1).

Coronectomy is an alternative surgical procedure to a complete extraction in cases of third molars with roots that are close to the mandibular canal (2). Many published

studies (3–16) report a low incidence of immediate postoperative complications, such as

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pain, swelling, and alveolitis. However, to exclude the risk of late infection caused by loss of pulpal vitality, clinicians need to know what happens to the root fragments

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beyond the first year of follow-up. Moreover, 1 year of follow-up, as reported in most published studies (3–16), is insufficient to observe root migration and root exposure. A recent systematic review (2) concluded that coronectomy could be used in clinical practice for extractions of third molars that presented a high risk of neurological injury. The authors also stated that more studies with longer follow-up are needed to evaluate any adverse effect of coronectomy (2). A 3-year follow-up is probably sufficient to

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evaluate any late complications from remnant root fragments in the alveoli. The purpose of this study was to determine whether coronectomy reduced neurological damage in cases of mandibular third molars in close proximity to the IAN. We evaluated the incidence of immediate (up to 1 month) and late postoperative

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migration.

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complications (between the 2nd and the 36th months), and also documented root

Materials and Methods Study design

We designed a prospective cohort study. The study population consisted of 94 healthy consecutive patients referred for mandibular third molar extractions to the Department of Oral Surgery of the Dental Clinic, Alma Mater Studiorum, University of Bologna, Italy. The study was explained to the patients, who provided written informed consent before any study-related procedures. The study protocol was approved by the Ethics

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ACCEPTED MANUSCRIPT Committee AUSL Città di Bologna, Italy (CE: 12098). The patients underwent coronectomies in the same department between December 2009 and June 2013. Study inclusion criteria were: age between 18 and 70 years old; ASA 1 status according to the American Society of Anesthesiologists (ASA) classification system; the presence of at least one third mandibular molar that needed extraction for previous episodes of

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pericoronitis or periodontal disease distal to the second molar; the presence on a

panoramic radiograph of at least one radiographic marker that was considered highly predictive of close contact between IAN and third molar roots (e.g., increased

radiolucency, narrowing, and interruption of the radiopaque border); and direct contact

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between the roots and the mandibular canal, due to the absence of cortical bone, as

evaluated by cone-beam computed tomography (CBCT) (17). Exclusion criteria were:

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systemic condition that precluded surgical treatment; the use of antibiotics or antiinflammatory agents in the 14 days before surgery; and third molars with caries, endodontic disease, or premature apexes. Study variables

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Predictor Variables

The predictor variables were surgeon’s experience (evaluated in years of clinical practice: expert surgeon, ≥ 10 years vs. less expert surgeon, < 10 years), length of surgery (in minutes), type of third molar inclusion (total or partial inclusion), and

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patient age (in years). Outcome variables

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Subjects having one or more of the clinical situations outlined below were defined as having complications. The absence of any complication was considered a success. If complications occurred up to 1 month from surgery, they were classified as immediate complications; complications that occurred between the 2nd and 36th months were classified as late complications. •

Neurological damage was evaluated at suture removal as the presence of hypoesthesia, hyperesthesia, or dysesthesia in the lower lip and mental region on the operated side. The presence of any alteration of lingual sensitivity was also

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ACCEPTED MANUSCRIPT evaluated. •

Postoperative pain was evaluated on a 10-cm horizontal visual analog scale (VAS), with degree of pain intensity ranging from “no pain” to “unbearable pain.” On this form, each patient reported pain intensity immediately after surgery, 6 h after surgery, and in the following 6 days, in the morning (7–9 am) and evening (8–9

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pm). Coronectomy was considered painful when patients recorded a score of 4 cm or greater on the 10-cm horizontal scale. Postoperative pain was considered to be a complication if the patient reported a score of 4 cm or greater on the 10-cm scale for 3 days or more in the postoperative week (14, 18). Patients also reported their use of •

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anti-inflammatory agents using a questionnaire on a daily basis.

Postoperative swelling was evaluated by patients on a daily basis, starting on the day

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after surgery, using a scale from 0 to 3 (14, 18). Swelling was considered a complication if present for 2 days or more during the first postoperative week. •

Fever was measured by the patient and reported on a daily basis. Fever was considered a complication if it was present for at least 2 days in the week after the coronectomy (14, 18).



Alveolitis was considered to be the presence of purulent exudates at suture removal

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or in the following weeks (18). •

Root exposure was defined as the eruption of retained roots in the oral cavity.



Pulpitis was considered to be severe pain without any periodontal or postoperative

• • •

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Other variables

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local infection.

Gender: male or female. Smoking habit: numbers of cigarettes smoked daily. Reason for treatment: the reason for the coronectomy was noted (pericoronitis or periodontal disease).



Failed coronectomy was considered to be any intra-operative root mobilization.



Root migration was considered to be any post-surgical radiographical movement of retained roots at 3, 6, 12, 24, and 36 months. A periapical radiograph with parallel technique was taken immediately after the coronectomy, and at 3, 6, 12, 24 and 36

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ACCEPTED MANUSCRIPT months. To evaluate root migration, we used only radiographs in which the mesiodistal width of the second molars was identical in all following radiographs. For a third molar in the vertical position with a single root, root migration was considered to be the distance between the cemento-enamel junction (CEJ) of the second molar and the root apex. For third molars in vertical positions with two completely

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separate apices, root migration was considered to be the distance between the

middle point of a line connecting the two apices and the CEJ of the second molar

(Figs. 1, 2). For third molars in horizontal positions, root migration was considered to be the distance between the middle point of a line joining the mesial and distal

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part of the root remnant and the CEJ of the second molar (Figs. 3, 4). The root

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migration values at 3, 6, 12, 24, and 36 months are reported.

Figures 1–4 •

Re-operation rate: the need for a second surgery was noted. The reason and type of second surgery were also recorded.



Secondary intention healing was considered to be wound healing with the

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Surgical procedures

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postoperative alveolus exposed to the oral cavity.

Preoperative care

At least 1 week before surgery, all of the patients underwent a professional tooth

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cleaning to decrease the bacterial load. They also received antibiotic prophylaxis (2 g amoxicillin and clavulanic acid in tablet form) 1 h before surgery. All of the patients rinsed for 1 min with 0.2% chlorhexidine mouth-rinse immediately before surgery.

Intra-operative care All of the surgical procedures were performed under local anesthesia with 2% mepivacaine and 1:100,000 adrenaline (Pierrel spa, Milano, Italy). The surgical procedures were performed as previously described (14) with a standardized surgical protocol to reduce intra-operator differences and coronectomy failure due to root

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ACCEPTED MANUSCRIPT mobilization. Surgeon’s experience was evaluated as years of clinical practice (expert surgeon, ≥ 10 years; less expert surgeon, < 10 years).

Postoperative care A periapical radiograph with parallel technique was taken immediately after the

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coronectomy, and at 3, 6, 12, 24, and 36 months. After surgery, all of the patients

received the same antibiotic (1 g amoxicillin and clavulanic acid every 8 h for 4 days), analgesic (600 mg ibuprofen, two tablets daily for 2 days), and antiseptic therapy (0.2% chlorhexidine mouth-rinse used from the day after surgery, twice per day, for 2 weeks).

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A form was given to each patient on which they reported the degree and intensity of pain on a 10-cm VAS, the use of anti-inflammatory agents, swelling, and fever on a

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daily basis. A second operator, who had not performed the surgery, removed the sutures 1 week after surgery, and noted any cases of secondary intention healing and complications during suture removal and during any follow-up visits. The same operator also received and evaluated the forms.

Data management

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Data management and analyses

A data collection form and data management system, including the development of data entry forms, was designed using Excel (Mac ver. 14.0.0; Microsoft Excel 2011). Data

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were entered by a single operator. Before entry, data were evaluated for accuracy and completeness; logical consistency was verified, and for quantitative data, ranges were computed. A hard copy of the entered data was verified and stored in individual

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coronectomy files. Data were analyzed using SPSS software (ver. 11.5; SPSS, Inc., Chicago, IL).

For quantification of the degree of migration, after manual development,

periapical radiographs (Kodak DF55 Ultra Speed, 2.4 × 4 cm) were transformed into computer images using an Epson Perfection V750 scanner to obtain 40, 800 × 56, 160pixel images at a resolution of 4800 dpi. During scanning, a piece of millimeter paper was inserted under each radiograph to permit calibration in millimeters. After scanning, the radiographs were saved in JPEG format. The radiographs were then analyzed using Osirix imaging software (ver. 4.0) (19-20).

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Statistical Analyses The association between study variables (age at coronectomy, surgeons’ experience, length of surgery, inclusion of third molar) and the main outcome (presence of complications) was described by means of contingency tables, and evaluated using χ2

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tests. Given the varying durations of follow-up, Kaplan-Meier analyses were performed. Cox hazard modeling was used to measure the risk that the study variables presented a significant association with the main outcome. The Kendall tau-b test was used to assess the correlation between pain and length of surgery, because the latter did not exhibit a

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Gaussian distribution, according to the Shapiro-Wilk test (p = 0.001). The association

between the experience of the surgeon and the duration of surgery was evaluated using

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the Mann-Whitney U-test.

The data on migration are presented as arithmetic means and 95% confidence intervals; when marked skewness was identified, medians and interquartile ranges were used instead. The Friedman test was performed to detect differences in migration over time; linear regression analysis was used to quantify this relationship. The Wilcoxon test for paired samples was performed to compare migration measures between

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successive time points; Bonferroni correction was used for these multiple comparisons.

Results

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We set the α level at 0.05 (20–21).

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The study population consisted of 94 patients (37 males, 57 females) with 116 third molars with a mean age of 28.99 ± 8.9 (range, 17–56) years treated with coronectomies. All the patients were healthy (ASA 1), according to the ASA classification system, except one with juvenile diabetes. Of the 94 patients, 81% were non-smokers, 15% smoked fewer than 10 cigarettes per day, and 4% smoked more than 10 cigarettes per day. Of the patients, 87 (93%) took no regular medication while the one (1%) diabetic took insulin, 3 (3%) patients took Eutirox (levothyroxine) and 3 (3%) female patients took oral contraceptives. Of the 116 third molars treated, 56 (48.3%) were totally impacted and 60

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ACCEPTED MANUSCRIPT (51.7%) were partially impacted. The teeth were treated by coronectomy due to pericoronitis (47.4%), periodontal disease (18.1%), or both (32.9%). In all cases, the patients had a preoperative pocket depth of 6 mm or more distal to the second molar before surgery. In 44.2% of cases, the operation was performed by a surgeon who had more than 20 years surgical experience. In 55.8% of cases, the operation was performed

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by surgeons with < 10 years surgical experience; however, these surgeons operated

under the supervision of the more-experienced surgeon. The surgeon with 20 years of

experience performed the surgery in less time (55 ± 2 min) than the surgeon with < 10 years experience (64 ± 2 min; p = 0.008). None of the coronectomies failed (0%).

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At 3 years, of the 94 patients (116 coronectomies), 28 patients (29 coronectomies) were lost to follow-up. Of the 28 patients, 15 were not seen at the 3-month, 2 at the 6-month,

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7 at the 12-month, and 4 at the 24-month recalls. All patients returned for suture removal, so it was possible to evaluate immediate postoperative complications in all cases. The immediate postoperative complications (up to 1 month after surgery) were 5 (4%) cases of postoperative alveolitis, 10 (9%) cases of postoperative swelling, and 10 (9%) cases of postoperative pain, and 0 cases of neurological damage. The time required for surgery showed a slight correlation with the postoperative pain evaluated at

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3 days (Kendall tau-b = 0.214, p = 0.004). Alveolitis was treated with antibiotic therapy (amoxicillin and clavulanic acid (1 g every 8 h for 4 days in tablet form) and antiseptic therapy (chlorhexidine 0.20% mouth-rinse twice a day for 15 days). Descriptive statistics of the study predictors that are associated with the presence of early (# 25) and

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Table 1

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late (# 5) complications are presented in Table 1.

The expert surgeons showed a significantly reduced incidence of complications (p = 0.04). The Cox model was applied to evaluate the influence of the operators’ experience; it was the only variable that was significantly associated with complications. The less experienced surgeons presented a risk of 2.069 times (95% CI = 1.004-4.263) versus expert surgeons in exposing the patient to complications. The median length of the surgery was 60 min (50–65 min); the incidence of complications was lower when the length of surgery was shorter, although this was not statistically

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ACCEPTED MANUSCRIPT significant (p = 0.103). The timing of complication onset is presented in Figure 5.

Figure 5

Table 2 reports the Kaplan-Meier summary of risk of complications. A success rate of

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74% at 6 months was estimated; no complication occurred after 12 months.

Table 2

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Late postoperative complications (1 month to 3 years after surgery) were one case of pulpitis and four cases of root eruption into the oral cavity. The four cases of root

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migration (three with pain due to periodontal disease and one case with pulpitis) were addressed by surgical root removal with no neurological damage to the IAN. According to these data, a second extractive surgery was needed in 6% of coronectomies. A second corrective surgery was necessary in four (3%) other cases: in three cases to remove enamel remnants that prevented bone formation around the roots, and in one case to reduce gingival hyperplasia distal to the second molar. In nine (8%) cases, there was a

Migration

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second intention healing; none of the cases had postoperative complications.

In the 116 coronectomies performed, 70 had comparable radiographs. Of the root

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fragments analyzed, 80% had postoperative migration. The mean root fragment migrations were 1.85 mm (95% CI = 1.52-2.18) at the 3-month follow-up, 2.36 mm

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(95% CI = 1.96-2.76) at the 6-month follow-up, 3.30 mm (95% CI = 2.71-3.88) at the 1-year follow-up, 4.63 mm (95% CI = 3.71-5.55) at the 2-year follow-up, and 4.826 mm (95% CI = 2.95-6.68) at the 3-year follow-up. The differences among the follow-up times were statistically significant (p = 0.02); in particular, the migration was significantly lower at 3 months than at 12 or 24 months (p = 0.001), and that at 6 months was significantly lower than that at 24 months (p = 0.001). Migration at 6 months decreased significantly with increasing age (Kendall tau-b = -0.273, p = 0.004). Based on the relationship between migration and time, it can stated that root migration

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ACCEPTED MANUSCRIPT increased every 12 months (median of the time series) by 0.844 mm (migration (mm) = 0.868 + 0.844 months); 28% of the variability in the data was due to the linear relationship (Figs. 6–9).

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Discussion Iatrogenic nerve injury can be a serious complication in mandibular third molar

extraction (1,2). The purpose of the present study was to examine whether coronectomy

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of the mandibular third molar reduced neurological damage in cases of teeth in close

proximity to the mandibular canal. We also evaluated post-operative complications in the postoperative 4 weeks and up to 3 years. None of the patients with high-risk

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mandibular molars experienced neurological injury to the IAN or LN, and no complications occurred within 12 months after surgery. Additionally, the total rate of postoperative complications seemed to correlate with the surgeons’ experience. Many (80%) of the analyzed retained roots migrated during the postoperative period, and the mean migration was 4.8 mm at the 3-year follow-up. Moreover, migration

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seemed to show a discontinuous movement pattern. During the first 2 years, the movement was regular, whereas between the second and third years, the roots moved little. In four cases, the retained roots erupted in the oral cavity due to large migration and a second surgery was necessary.

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In this study, the incidence of immediate complications, such as pain and swelling, was lower than that reported in studies of complete extractions of partially or completely impacted third molars (18, 22–24). Although a coronectomy is a time-

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consuming surgical procedure, it is less aggressive than a complete extraction with regard to the surrounding soft and mineralized tissues. As a consequence of this reduced intraoperative trauma, few cases of pain or swelling during the first postoperative week were observed. The incidence of alveolitis was comparable to previous reports (18, 22– 24). Expert surgeons significantly reduced the incidence of complications, because in this surgical procedure, a specific learning period is required. For this reason, it is important to consider coronectomy as a proper technique, not as incomplete extraction. Regarding late complications, the 2- and 3-year follow-up examinations showed that the

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ACCEPTED MANUSCRIPT root remnants were, after initial migration, covered by bone, with no apical infection. Only one case was diagnosed with pulpitis and re-intervention was necessary for root extraction at 6 months after the coronectomy. The presence of a deep periodontal pocket distal to the second molar could have been responsible for the late pulp infection. While pulpitis is possible, it is rare; we experienced only one case in 116

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coronectomies. A recent study discussed the potential of pulp tissue in terms of

regeneration after injury (25). Moreover, root migration, even in the case of pulpitis at 3-6 months after a coronectomy, facilitates safer extraction because the root remnants have moved away from the mandibular canal. Migration, as described by Marks &

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Schroeder (26), is a physiological and continuous movement of the dental root. After a coronectomy, this movement can start again when the third molar crown is removed. In

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our study of 70 migrated root fragments, only 4 were removed due to migration. Three roots caused periodontal disease distal to the second mandibular molar and one root, although asymptomatic, was removed 12 months after surgery because the patient was moving to another town and would have been unable to attend follow-up appointments. The high frequency of root movement and the low rate of second surgery due to migration confirms the hypothesis of the natural and physiological significance of

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migration. This is consistent with the report by Leung & Cheung (11), who carried out the same analysis using orthopantomography. Considering our and others’ data (11), during a 3-year follow up, no associated complication was observed. This is an important issue for clinicians who cannot provide such a strict follow-up protocol after

inadequate.

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surgery. However, we consider a 6-month follow up, as suggested by Pogrel (6), to be

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In this study, in some cases root migration of 4-5 mm was observed; to avoid the risk of premature second surgery, it is important to grind the root fragments as much as possible. Considerable grinding is advisable in third molars in mesial or horizontal impaction, where in cases of consistent migration the root could impact the distal surface of the second molar, and at the same time maintain proximity with the mandibular canal. For this reason, it may be useful in clinical practice to consider the regression equation that expresses an increase of 0.844 mm every 12 months (i.e., 0.070 mm per month). Clinical application of this equation could permit the surgeon, using an intra-operative radiographic examination, to determine whether the root

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ACCEPTED MANUSCRIPT grinding is sufficient. The strengths of this study include standardization of the surgical protocol and the preoperative diagnosis after a CBCT examination. With accurate standardization of the surgical protocol, this is the first reported study where no coronectomy failed due to intra-operative root mobilization. Additionally, with the pre-operative CBCT, the

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surgeon could better evaluate the root anatomy and decide between coronectomy and

extraction (it may be safer to extract third molars with conical roots even if they are in close proximity to the mandibular canal). Moreover, standardization of the surgical procedure provided good results in terms of reduced immediate postoperative

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complications, even when the surgical procedure was performed by surgeons with < 10 years experience. Surgeons with less experience took longer to complete the

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coronectomy, and pain was slightly correlated with the length of surgery, but not with swelling in the first postoperative week. The weakness of this study was the small number of cases. Further studies with a larger number of cases are necessary to investigate postoperative complications; in addition the relationship between such complications and patient age should be evaluated, as patient age generally affects the

Conclusions

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rate of complications (1).

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In this study, coronectomy of mandibular third molars did not result in temporary or permanent injury to the IAN or the LN. Moreover, coronectomy showed a low rate of immediate postoperative complications. Migration of the retained roots was a common

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event, but required removal of the retained roots in only a few cases. The 2- to 3-year follow-up showed an absence of late complications; however, surgeons should inform patients that a second surgery may be required within the first year. We recommend further studies with a larger number of patient samples to investigate any differences in postoperative complications in relation to patient age.

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23. Blondeau F, Daniel NG: Extraction of impacted mandibular third molars: postoperative complications and their risk factors. J Can Dent Assoc May, 73(4): 325, 2007.

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24. Suddiqi A, Morkel JA, Zafar S: Antibiotic prophylaxis in third molar surgery: a randomized double-blind placebo-controlled clinical trial using split-mouth technique.

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Int J Oral Maxillofac Surg Feb; 39(2): 107-14. Epub 2010 Feb. 1 25. Schmalz G and Galler KM: Tissue injury and pulp regeneration. J Dent Res 90(7):828-829, 2011.

26. Marks SC, Schroeder HE, Andreasen JO: Theories and Mechanisms of tooth eruption. Chapter 1. Textbook and color atlas of tooth impactions. Munksgaard ed. 1997.

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Table 1. Associations between study variables and primary outcome Complications n = 30 Pres

Absent

variables

ent

Expert

12 53

surgeon

40% 62%

(≥ 10 years

p = 0.04

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Study

18 65

surgery < 60

60% 76%

min (median)

p = 0.103

Age of the

16 59

patient at

53% 69%

coronectomy p = 0.132

Type of third

14 43

molar

47% 50%

impaction

p = 0.753

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n = 57

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< 30 years

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Length of

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experience)

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Table 2. Kaplan-Meier summary of risk of complications: cumulative event-free probabilities Time (months)

Number of complications

Probability density

Std error of Probability density

Hazard rate of future treatment after coronectomy

Std error of hazard ratio

0 26 0.039 0.007 0.04 0.01 6 4 0.007 0.003 0.01 0.001 12* 0 0 0 *12-month interval start time from which no complication was reported.

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Estimate

Std error

0.776 0.736 0

0.039 0.042 0

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Figures 1 & 2. To evaluate root movement in a double-root third molar, the distance between the middle point of a line connecting the two apices and the cement-enamel

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junction (CEJ) of the second molar was examined.

Figures 3 & 4. To evaluate root migration, in a single-root third molar, the distance between the CEJ and root apex was examined.

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Figure 5. Two peaks of complications were evident: at 1 month, < 1 month, from 1 to

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10 months.

Figure 6. Periapical radiograph taken before suturing to see the root of a mandibular left third molar after coronectomy.

Figure 7. Periapical radiograph taken at the 3-year follow-up of the same root shown in Figure 6. The root migration and the bone apposition distal to the second molar can be

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Figure 8. Periapical radiograph taken before suturing where the root of a mandibular

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right third molar after coronectomy can be seen.

Figure 9. Periapical radiograph taken at the 3-year follow-up of the same root shown in

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Figure 8. The bone apposition distal to the second molar and the absence of root migration can be seen.

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What Are the Types and Frequencies of Complications Associated With Mandibular Third Molar Coronectomy? A Follow-Up Study.

Coronectomy has been proposed for impacted third molars in close proximity to the inferior alveolar nerve (IAN) to avoid neurologic injury. Immediate ...
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