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Prognostic Factors of Clinical Outcomes in Endodontic Microsurgery: A Prospective Study
Clinical Research
Prognostic Factors of Clinical Outcomes in Endodontic Microsurgery: A Prospective Study Minju Song, DDS, MSD, PhD,* Sahng Gyoon Kim, DDS, MS,† Seung-Jong Lee, DDS, MS, PhD,‡ Baekil Kim, DDS, MSD, PhD,§ and Euiseong Kim, DDS, MSD, PhD‡ Abstract Introduction: This prospective study examined the potential prognostic factors of endodontic microsurgery and compared the predictors of an isolated endodontic lesion with those of both an isolated endodontic lesion and an endodontic-periodontal lesion. Methods: Data were collected from the Microscope Center of the Department of Conservative Dentistry at the Dental College of Yonsei University, Seoul, Korea, between March 2001 and March 2011. A total number of 584 teeth were included, and all clinical procedures were performed by a single operator (E.K.). The evaluation was performed at least 1 year after surgery. For statistical analysis of the predisposing factors, the chi-square test and logistic regression were performed. Results: Of the 584 cases treated, 431 cases came for recall after a period of at least 12 months. Sex (female), tooth position (anterior), arch type (maxilla), and lesion type (isolated endodontic lesion) were found to have a positive effect on surgical outcome. With regards to isolated endodontic lesions, the tooth position (anterior), arch type (maxilla), and type of restoration (single/splinted crown, short bridge, and removable partial denture abutment) were found to be pure positive predictors. Conclusions: In endodontic microsurgery, it is likely that preoperative factors, particularly the tooth position and arch type, have a greater influence on the healing outcome than intra- and postoperative factors. (J Endod 2013;39:1491–1497)
Key Words Endodontic microsurgery, healing outcome, prognostic factors, prospective clinical study, tooth position
B
efore the advent of surgical operating microscopes, the success rates of traditional endodontic surgery ranged from 43% to 75% (1), which is lower than those of nonsurgical retreatments (2). However, root-end surgery has changed radically over the last 20 years with the implementation of microsurgical techniques and the use of advanced equipment. In recent years, endodontic microsurgery including the use of high-power illumination and magnification (10 and higher), ultrasonic root-end preparation, and biocompatible root-end filling materials has produced favorable outcomes in the 90% success rate range (1, 3). Several studies have reported on the prognostic factors for apical surgery, which are not classified according to the type of surgical technique such as traditional rootend surgery, contemporary root-end surgery, and endodontic microsurgery (4–6). Numerous authors have analyzed the effects of individual variables on the outcome of endodontic surgery. Most predictable preoperative prognostic factors in many studies include the length and quality of existing root filling, the presence of preoperative lesion, the presence of post and the lesion size. The intraoperative factors include the placement of root-end filling, the root-end preparation methods, the root-end filling materials, and the operator’s skill. The postoperative factors include the apical and coronal seal (4–8). In the past decade, many studies have reported on the clinical outcomes of endodontic microsurgery (3, 9, 10). However, there are only a few reports related to the prognostic factors of endodontic microsurgery. Von Arx et al (10) evaluated the influence of various predictors on healing outcome 1 year after endodontic microsurgery with 194 teeth (10). Using logistic regression, the pain at initial examination (P = .04) was the only predictor reaching significance. In another study by von Arx et al (11) that assessed the 5-year outcome and its predictors in a cohort for which the 1-year outcome was reported, 2 significant outcome predictors were found: a mesial-distal bone level at #3 mm versus >3 mm from the cementoenamel junction (78.2% vs 52.9%, P < .02) and root-end filling with ProRoot MTA (Dentsply, Tulsa, OK) versus Super EBA (Harry J. Bosworth, Skokie, IL) (86.4% vs 67.3%, P < .004). In our previous retrospective study (12), the potential prognostic factors for endodontic microsurgery were sex (female), tooth position (anterior), lesion type (isolated endodontic lesion) and root-end filling material (ProRoot MTA and Super EBA). When periodontally involved lesions were excluded, an isolated endodontic lesion might reduce the effects of many variables. The tooth position (anterior) was found to be a pure predictor of an endodontic lesion affecting the clinical outcome. However, prognostic factors have been rarely reported for endodontic microsurgery, and more research is needed. This prospective study examined the potential prognostic
From the *Department of Conservative Dentistry, Gangnam Severance Dental Hospital, †Division of Endodontics, College of Dental Medicine, Columbia University, New York, New York; ‡Microscope Center, Department of Conservative Dentistry and Oral Science Research Center, College of Dentistry, Yonsei University, Seoul, Korea; and §Department of Preventive Dentistry and Public Oral Health, College of Dentistry, Yonsei University, Seoul, Korea. Supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010-0021281). Address requests for reprints to Dr Euiseong Kim, Microscope Center, Department of Conservative Dentistry and Oral Science Research Center, College of Dentistry, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu, Seoul 120-752, South Korea. 0099-2399/$ - see front matter Copyright ª 2013 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2013.08.026
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Clinical Research factors for the outcome of endodontic microsurgery and compared the predictors for isolated endodontic lesions with those of both isolated endodontic lesions and endodontic-periodontal lesions.
Methods Case Selection This study was approved by the Yonsei Dental College, Yonsei University Institutional Review Board (number 2001–2), and informed consent was acquired from all participants. Data were collected from the Microscope Center of the Department of Conservative Dentistry at the Dental College, Yonsei University, Seoul, Korea, between March 2001 and March 2011. Teeth with a mobility class II or greater, horizontal and vertical fractures, and perforation were excluded from the study. A total number of 584 teeth requiring endodontic surgery were included in the study. Surgical Procedure All clinical procedures were performed according to the Yonsei protocol described in a previous study (12) and were performed by a single operator (E.K.). With the exception of the incisions, flap elevation, and suturing, all surgical procedures were performed using a surgical operating microscope (OPMI PICO; Carl Zeiss, G€ottingen, Germany). Patients were anesthetized with 2% lidocaine with 1:80,000 epinephrine, and sulcular or mucogingival incisions were chosen depending on the type and esthetic requirements of the case. For additional hemostasis during surgery, cotton pellets soaked in 0.1% epinephrine (Bosmin; JeilInc, Seoul, Korea) and/or ferric sulfate (Astringedent; Ultradent Products, Inc, South Jordan, UT) were applied topically as required. The tissue was gently reflected toward the apical area with a Molten 2–4 curette (G Hartzell and Son Inc, Concord, CA). In cases with mandibular second premolars or first molars, the mental foramen was identified by reflecting a vertical incision that was placed mesially to the first premolar. A KP1 retractor (G Hartzell and Son Inc) was then placed just coronal to the mental foramen, and a 1.5-cm-long and 2-mm-deep groove was made by using a Lindemann bur (7, 13). This groove was designed to protect the mental foramen during the surgical procedure by creating a rest for the serrated end of the retractor. Osteotomies were performed with an H161 Lindemann bone cutter (Brasseler, Savannah, GA) in an Impact Air 45 handpiece (Palisades Dental, Englewood, NJ). A Columbia 13–14 curette (G Hartzell and Son Inc) and a Jacquette 34/35 scaler (G Hartzell and Son Inc) were used for periradicular curettage. A 2- to 3-mm root tip with a 0 to 10 beveled angle was resected with a 170-tapered fissure bur under copious sterile distilled water irrigation. The resected root surface was then stained with methylene blue and inspected with a micromirror under 20 to 26 magnification to examine the entire root tip resection and to search for anatomic details. Root-end preparation extending 3 mm into the canal space along the long axis of the root was made with KIS ultrasonic tips (Obtura Spartan, Fenton, MO) driven by a piezoelectric ultrasonic unit (Spartan MTS, Obtura Spartan). Isthmuses, fins, and other significant anatomic irregularities were identified and prepared with the ultrasonic instruments. After the root-end preparation was completed, the prepared cavity was inspected with a micromirror at a high magnification (20–26) to ensure that no debris existed in the root-end preparation. The prepared root-end cavity was dried with a Stropko irrigator/drier (Obtura Spartan). The root-end filling material used was Intermediate Restorative Material (IRM; Caulk Dentsply, Milford, DE), Super EBA, or ProRoot MTA. The adaptation of the filling material to the canal apical walls was confirmed with the aid of an operating microscope at high magnifica1492
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tion. A postoperative radiograph was taken to verify correct placement and an absence of excess material in the bony crypt, and the flap was closed and sutured with 5 0 monofilament sutures. A postoperative mouthwash (0.2% chlorhexidine gluconate [Hexamedin; Bukwang Phar Co, Ansan, Korea]) was commonly prescribed, and the sutures were removed 4–7 days later. After surgery, an operation record form was made with the preoperative and intraoperative factors from the patient records and periapical radiographs. The operation record form was updated with the postoperative events whenever the patients were recalled periodically to assess the clinical and radiographic signs of healing.
Evaluation Factors Evaluation factors were divided into preoperative, intraoperative, and postoperative factors similar to the previous retrospective study (12). The preoperative factors included the patients’ age and sex, tooth position, arch type, preoperative signs and/or symptoms, probing depth, root filling state (length, density, material), type of root canal treatment (initial treatment, retreatment), history of apical surgery, type of a preoperative restoration, and lesion type. The intraoperative factors included the root-end filling material, the presence of complications such as sinus wall perforation or nerve damage, and the presence of a ‘‘through-and-through’’ lesion. The postoperative factors included the type of postoperative restoration at follow-up. The preoperative signs and/or symptoms were defined as preoperative pain or swelling. The adequate root filling length was defined as a filling within 2 mm from the apex, and the criterion for adequate density was a filling without voids and with uniform radiopacity. The lesion type was divided into isolated endodontic lesions (class A, B, or C) and endodontic-periodontal combined lesions (class D, E, or F) as classified by Kim and Kratchman (14). The type of preoperative and postoperative restoration was divided into 4 subgroups: single/splinted crown, short bridge, long bridge, and removable partial denture (RPD) abutment. Resin cores in the anterior teeth were included in the single/splinted crown subgroup. A short bridge was defined as having less pontics than abutments. A long bridge was defined as having the same number of pontics or more pontics than abutments. Regardless of the type of restoration, if the tooth was used as an abutment for an RPD, it was categorized as an RPD abutment. All data were recorded on the operation record form by a single doctor, except for the radiographic interpretations in which 2 examiners had to concur. Radiographic interpretation included root filling density and root filling length. Clinical and Radiographic Evaluation The patients were usually followed up at 3, 6, and 12 months and every year thereafter. On every recall visit, a routine examination was performed, and periapical radiographs were taken. The clinical data, including the signs and/or symptoms or loss of function, tenderness to percussion or palpation, subjective discomfort, mobility, sinus tract formation or periodontal pocket formation, postoperative complications, and type of restoration at follow-ups, were included in the operation record form. The evaluation was performed at least 1 year after surgery. The postoperative radiographs were evaluated independently by 2 examiners using the same criteria used by Molven et al (15, 16). The healing classifications were as follows: 1. 2. 3. 4.
Complete healing: The re-establishment of the lamina dura Incomplete healing: Scar tissue Uncertain healing Unsatisfactory healing JOE — Volume 39, Number 12, December 2013
Clinical Research Assessment of Outcome Healing was judged clinically and radiographically. The criteria for a successful outcome included the absence of clinical signs and/or symptoms and radiographic evidence of complete or incomplete healing. The criteria for failure included any clinical signs and/or symptoms or radiographic evidence of uncertain or unsatisfactory healing. Analyses of Data For statistical analysis of the predisposing factors, the dichotomous outcome (success or failure) was used as the dependent variable. A univariate description with the percentage frequencies was generated to characterize the study material. Significant associations between the outcome and all the variables were examined using chi-square tests or Fisher exact tests to identify the potential outcome predisposing factors. Multiple analyses of the predisposing factors using logistic regression models were performed. All statistical analyses were performed with SPSS v19.0 software (IBM Corp, Somers, NY), and the level of significance was set at P < .05.
Of the 584 cases treated, 431 cases came for recall after a period of at least 12 months. A recall rate of 73.8% (431/584) was achieved. Table 1 presents the distribution of cases in relation to the recall period. Table 2 lists the distribution of the cases according to the variables/category and bivariate analysis. The Cohen kappa value for the density and length of pre-existing root filling as well as postoperative radiographs ranged from 0.87–0.95 (Table 3). Of the preoperative factors examined, significant differences were observed for age (P < .001), sex (P = .027), tooth position (P = .002), arch type (P = .002), and lesion type (P = .001) with regards to both isolated endodontic lesions and endodontic-periodontal lesions (Table 2). Of the intraoperative and postoperative factors, none were found to be significant (P > .05). Of the 431 cases recalled, 87 cases were related to endodontic-periodontal combined lesions, and 344 cases were related to isolated endodontic lesions. With regards to the isolated endodontic lesions, the age (P = .005), tooth position (P = .006), and arch type (P = .002) were found to be significant among the preoperative factors. The type of postoperative restoration (P = .023) was also found to be significant (Table 2). As with the previous results of the retrospective study (12), variables with a significance level of 0.05 or less were included in the logistic regression model. Table 4 lists the point estimate, 95% confidence intervals of the odds ratios, and the P value of the significant remaining parameters. For both isolated endodontic lesions and endodonticperiodontal lesions, sex (female), tooth position (anterior), arch type (maxilla), and lesion type (endodontic lesion) were found to have a positive effect on the outcome. On the other hand, with the isolated endodontic lesions, the tooth position (anterior) and arch type TABLE 1. Distribution of Cases Related to the Recall Period 1 year 2 years 3 years 4 years 5 years 6 years 7 years 8 years 9 years 10 years
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Discussion This study aimed to identify the significant prognostic factors in endodontic microsurgery that can guide us in the hope of achieving higher success rates. The prognostic factors should be considered in case selection because the treatment outcome may depend on them. As with our previous retrospective study (12), similar evaluation factors were investigated in this prospective study. The results of this study indicate that several factors, including age, sex, tooth position, arch type, lesion type, and type of postoperative restoration, had a significant effect on the healing outcome of endodontic microsurgery. It appears that the preoperative factors, particularly the tooth position and arch type, had a greater effect on the healing outcome than the intra- and postoperative factors.
Age
Results
Recall period
(maxilla) were significant (Table 4). The type of postoperative restoration (long bridge) was found to have a negative effect on the outcome (P = .022).
No. of teeth (%) 110 (18.8) 120 (20.7) 40 (6.8) 37 (6.3) 18 (3.1) 27 (4.6) 23 (3.9) 30 (5.1) 23 (3.9) 3 (0.5)
In many studies, the patients’ age has had no significant effect on the treatment outcome (7, 17). However, Barone et al (5) reported that the rate of healing in patients older than 45 years was 84% compared with 68% for younger patients. On the other hand, in the present study, the highest success rate was reported in patients under 20 years and tended to decrease as the patients aged (P < .05). Perhaps this can be attributed to the younger patients having a better healing potential. This result should be interpreted with caution because the cutoff age for statistical analysis varies among studies.
Sex This study indicated that males had a poorer success rate than females. In the periodontal literature, it has been shown that males are more prone to periodontal infection than females (18). In an endodontic outcome study (19), it was shown that male patients had a significantly lower success rate after initial root canal treatment when compared with female patients. In a mouse experimental study of pathologic endodontic bone loss, male mice suffered more bone loss with the increase in inflammatory infiltrate (20). However, the clinical significance of sexual dimorphism in periapical inflammation and wound healing has not been fully elucidated.
Tooth Position and Arch Type There are a few studies on apical surgery in which tooth position was not significant on the healing outcome of endodontic surgery (17, 21, 22). A few studies have investigated the outcomes of endodontic microsurgery per tooth group, but they were just descriptions without statistical analysis (9, 23). In this prospective study, the anterior, premolar, and molar teeth had significantly different success rates with microsurgery (P < .05). A significant difference was also observed between the maxillary and mandibular groups (P < .05). In addition, the success rates were analyzed according to the tooth position within the jaw. Within the mandible, there was no significant difference found in the success rate among the tooth positions. However, within the maxilla, the success rates differed according to tooth position (P < .001). The maxillary anterior teeth tended to have a higher success rate than the other tooth groups (14), which might be because of the relatively easy access and less complicated root anatomy (24). The use of a surgical operating microscope does not enhance access (25). The lower success rates in lower anterior and molar teeth compared with upper anterior teeth may be Prognostic Factors in Endodontic Microsurgery
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Variables/category
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Age <20 21–30 31–40 41–50 51–60 >60 Sex Male Female Tooth position Anterior Premolar Molar Arch type Maxilla Mandible Right vs left Right Left Preoperative signs and symptoms No Yes Probing depth #4 mm 5–7 mm $8 mm Root filling length Adequate Inadequate Root filling density Adequate Inadequate Root filling material Empty Gutta-percha Other Previous treatment Initial Retreatment Previous apical surgery No Yes Preoperative restoration type Single/splinted crown Short bridge Long bridge RPD abutment Lesion type Endodontic
Success, n (%)
Failure, n (%)
15 (100.0) 87 (92.6) 108 (92.3) 67 (78.8) 63 (86.3) 29 (61.7)
0 (0.0) 7 (7.4) 9 (7.7) 18 (21.2) 10 (13.7) 16 (38.3)
136 (81.0) 233 (88.6)
32 (19.0) 30 (11.4)
208 (91.2) 69 (80.2) 92 (78.6)
20 (8.8) 17 (19.8) 25 (21.4)
272 (88.9) 97 (77.6)
34 (11.1) 28 (22.4)
155 (87.6) 214 (84.3)
22 (12.4) 40 (15.7)
50 (86.2) 319 (85.5)
8 (13.8) 54 (14.5)
305 (86.9) 30 (78.9) 34 (81.0)
46 (13.1) 8 (21.1) 8 (19.0)
172 (83.5) 149 (90.3)
34 (16.5) 16 (9.7)
185 (84.5) 136 (89.5)
34 (15.5) 16 (10.5)
36 (87.8) 280 (86.4) 5 (83.3)
5 (12.2) 44 (13.6) 1 (16.7)
272 (86.3) 49 (87.5)
43 (13.7) 7 (12.5)
322 (86.6) 47 (79.7)
50 (13.4) 12 (20.3)
311 (85.4) 31 (93.9) 13 (72.2) 14 (87.5)
53 (14.6) 2 (6.1) 5 (27.8) 2 (12.5)
304 (88.4)
40 (11.6)
Endo
Chi-square value
P value
30.529
.000
Success, n (%) 13 (100.0) 67 (93.1) 90 (94.7) 60 (83.3) 47 (85.5) 27 (73.0)
4.860 12.487
9.183 0.993 0.019 2.580
3.641 0.923 0.410
0.054 1.968 4.322
10.520
Failure, n (%)
Chi-square value
P value
16.067
.005
0.605
.437
10.342
.006
9.610
.002
0.531
.466
0.080
.778
1.436
.529
0.160
.689
0.102
.750
0.668
.726
0 (0.0) 5 (6.9) 5 (5.3) 12 (16.7) 8 (14.5) 10 (27.0)
.027 110 (86.6) 194 (89.4)
17 (13.4) 23 (10.6)
180 (93.3) 54 (83.1) 70 (81.4)
13 (6.7) 11 (16.9) 16 (18.6)
230 (91.6) 74 (79.6)
21 (8.4) 19 (20.4)
126 (86.9) 178 (89.4)
19 (13.1) 21 (10.6)
43 (89.6) 261 (88.2)
5 (10.4) 35 (11.8)
273 (88.6) 24 (88.9) 7 (77.8)
35 (11.4) 3 (11.1) 2 (22.2)
145 (88.4) 124 (89.9)
19 (11.6) 14 (10.1)
147 (88.6) 122 (89.7)
19 (11.4) 14 (10.3)
30 (85.7) 235 (89.4) 4 (100.0)
5 (14.3) 28 (10.6) 0 (0.0)
234 (88.6) 35 (92.1)
30 (11.4) 3 (7.9)
270 (89.1) 34 (82.9)
33 (10.9) 7 (17.1)
256 (88.3) 25 (100.0) 12 (75.0) 11 (84.6)
34 (11.7) 0 (0.0) 4 (25.0) 2 (15.4)
.002
.002 .334 .890 .275
.056 .166 .921
.816
.781
.161
.295
.208
.001
6.728
.053
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TABLE 2. Distribution of Cases per Variables/Category and Bivariate Analysis
TABLE 3. Interexaminer Reliability in Evaluating Preoperative and Postoperative Radiographs
.023
1.000
1.000
.529
.616
Clinical Research
Factors
8.730
0.894
1.274
Root filling density Root filling length Postoperative radiographs
Agreement (%)
Cohen kappa value
97.57 96.23 97.22
0.95 0.92 0.87
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Endo, isolated endodontic lesion; Endo + endo-perio, both isolated endodontic lesion and endodontic-periodontal lesion; MTA, mineral trioxide aggregate; RPD, removable partial denture.
34 (12.1) 0 (0.0) 4 (25.0) 2 (15.4) 311 (85.4) 31 (93.9) 13 (72.2) 14 (87.5)
53 (14.6) 2 (6.1) 5 (27.8) 2 (12.5)
4.322
.208
1.000 59 (14.5) 3 (12.0) 347 (85.5) 22 (88.0)
354 (85.5) 15 (88.2)
60 (14.5) 2 (11.8)
0.327 29 (14.8) 31 (13.9) 2 (16.7) 167 (85.2) 192 (86.1) 10 (83.3)
22 (25.3)
Endodontic-periodontal Lesion type (endodontic lesion) A B C Root-end filling material MTA Super EBA IRM Complication Absence Presence Through-and-through lesion No Yes Postoperative restoration type Single/splinted crown Short bridge Long bridge RPD abutment
65 (74.7)
247 (87.9) 34 (100.0) 12 (75.0) 11 (84.6)
38 (11.8) 2 (9.5) 285 (88.2) 19 (90.5)
39 (11.8) 1 (7.7) 292 (88.2) 12 (92.3) 1.000
.835
45 (91.8) 161 (89.0) 98 (86.0)
135 (90.0) 162 (87.1) 7 (87.5)
4 (8.2) 20 (11.0) 16 (14.0)
15 (10.0) 24 (12.9) 1 (12.5)
attributed to limited access that can potentially hinder the precise surgical procedures.
Lesion Type In this prospective study, the lesion type was a significant predictor (95% confidence interval, 1.120–3.793, P = .020). The isolated endodontic lesion had a higher success rate than the endodonticperiodontal combined lesion (88.4% vs 74.7%). A similar pattern was reported in our previous study (12), and several studies have also suggested a poorer prognosis for teeth with periodontally involved lesions (3, 26). The loss of alveolar bone induces the apical migration of gingival epithelial cells that forms a long junctional epithelium, making periodontal reattachment difficult. The long junctional epithelium may serve as a path for reinfection and prevent the healing process (27). Therefore, in situations of endodonticperiodontal lesions, a regeneration technique such as guided tissue regeneration might be necessary to help the lesions to heal. With a combined endodontic-periodontal lesion, the prognosis of the teeth may depend on secondary periodontal support in addition to the endodontic microsurgery (28). Therefore, the predisposing factors of an isolated endodontic lesion after endodontic microsurgery would be different from those of an endodontic-periodontal lesion. Age (P < .001), sex (P = .027), tooth position (P = .002), arch type (P = .002), and lesion type (P = .001) were found to be significant predictors of success for combined lesions, whereas age (P = .005), tooth position (P = .006), arch type (P = .002), and type of postoperative restoration (P = .023) were found to be significant for isolated endodontic lesions. Tooth position (anterior) and arch type (maxilla) seemed to be important positive predictors of surgical success (logistic regression, P < .05) for isolated endodontic lesions. Type of Postoperative Restoration In the present study, teeth restored with single/splinted crowns presented a higher healing rate than teeth restored with long bridges (95% confidence interval, 1.246–17.382, P = .022). A long bridge was defined as a restoration in which the number of pontics is the same or more than the number of abutments. In fixed prosthodontics with several pontics, the ability of the abutment teeth to resist applied forces is important for the prognosis (29). Endodontic microsurgery leaves shorter roots after root-end surgery, which can lead to an unfavorable outcome based on Ante’s law, which suggests that when the root surface area of the abutment is less than the root surface area of the teeth being replaced, fixed prosthodontics should not be placed (30). Moreover, with overloading of abutments with a long span, it might be hard for the root-end filling materials of the abutments to bear the occlusal force and thus fail to form a bacteria-tight seal. Other Factors Other preoperative factors associated with previous treatment status such as root filling state (length, density, materials), type of Prognostic Factors in Endodontic Microsurgery
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Clinical Research TABLE 4. Logistic Regression Model Endo + endo-perio
Endo
95% confidence interval Variables Sex Female versus male Tooth position Anterior versus premolar Anterior versus molar Arch type Maxilla versus mandible Lesion type Endodontic versus endodonticperiodontal Postoperative restoration type Single vs short bridge Single vs long bridge Single versus RPD abutment
95% confidence interval
Point estimate
Lower
Upper
P value
Point estimate
Lower
Upper
P value
1.926
1.090
3.403
.024
1.489
0.733
3.027
.271
2.176
1.057
4.479
.035
3.060
1.210
7.739
.018
2.288
1.154
4.537
.018
3.445
1.407
8.437
.007
1.922
1.059
3.485
.032
2.118
1.024
4.381
.043
2.061
1.120
3.793
.020
0.000 4.653 1.330
0.000 1.246 0.253
0.000 17.382 6.976
.998 .022 .736
Endo, isolated endodontic lesion; Endo + endo-perio, both isolated endodontic lesion and endodontic-periodontal lesion; RPD, removable partial denture. The coefficient of determination = 0.115 (total) and the coefficient of determination = 0.157 (isolated endodontic lesion).
previous treatment (initial treatment or retreatment), and history of apical surgery did not have a significant relationship with healing outcome. Furthermore, of the intraoperative and postoperative factors, none was found to be significant (P > .05) except for the type of postoperative restoration. Endodontic microsurgery uses a surgical operating microscope to allow clinicians to identify and address the causes of endodontic failure. Therefore, with the strict application of microsurgical techniques, the variables related to previous treatment status and procedures may not have a significant effect on the outcome of endodontic microsurgery. Smoking habits were not evaluated in the present study but might be related to the healing process. There is a paucity of evidence relating smoking to endodontic disease, but smoking has been suggested to be related to a potential increase in surgical complications (31). Smoking is likely to affect healing in surgical endodontic cases that involve bony and soft-tissue healing (32, 33). The present study did not include the habit of smoking as an evaluation factor, and, therefore, any correlation between healing and smoking could not be analyzed. Further studies are needed to assess the relationship between smoking and healing. In this prospective study, endodontic microsurgery reduced the effect of many variables in the healing outcome compared with traditional root-end surgery. This is consistent with our previous retrospective study (12). Our 2 studies showed that age, sex, tooth position, lesion type, and postoperative restoration were important predictors. Other variables, including the root filling length and root-end filling material, were not found to be significant in this prospective study, but they were significant in the retrospective study. In conclusion, the potential positive prognostic factors on the surgical outcome with regards to both isolated endodontic lesions and endodontic-periodontal lesions include sex (female), tooth position (anterior), arch type (maxilla), and lesion type (isolated endodontic lesion). The tooth position (anterior), arch type (maxilla), and type of restoration (single/splinted crown, short bridge, and RPD abutment) were found to be positive predictors for clinical outcome of an isolated endodontic lesion. More prospective studies need to be performed to further investigate the effects of various prog1496
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nostic factors including the effect of smoking on the healing outcome of endodontic microsurgery.
Acknowledgments The authors deny any conflicts of interest related to this study.
References 1. Setzer FC, Shah SB, Kohli MR, et al. Outcome of endodontic surgery: a meta-analysis of the literature—part 1: comparison of traditional root-end surgery and endodontic microsurgery. J Endod 2010;36:1757–65. 2. Torabinejad M, Corr R, Handysides R, et al. Outcomes of nonsurgical retreatment and endodontic surgery: a systematic review. J Endod 2009;35:930–7. 3. Kim E, Song JS, Jung IY, et al. Prospective clinical study evaluating endodontic microsurgery outcomes for cases with lesions of endodontic origin compared with cases with lesions of combined periodontal-endodontic origin. J Endod 2008;34:546–51. 4. Friedman S. The prognosis and expected outcome of apical surgery. Endod Top 2005;11:219–62. 5. Barone C, Dao TT, Basrani BB, Wang N, et al. Treatment outcome in endodontics: the Toronto study-phases 3, 4, and 5: apical surgery. J Endod 2010;36:28–35. 6. von Arx T, Penarrocha M, Jensen S. Prognostic factors in apical surgery with rootend filling: a meta-analysis. J Endod 2010;36:957–73. 7. Rahbaran S, Gilthorpe MS, Harrison SD, et al. Comparison of clinical outcome of periapical surgery in endodontic and oral surgery units of a teaching dental hospital: a retrospective study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001;91: 700–9. 8. Lustmann J, Friedman S, Shaharabany V. Relation of pre- and intraoperative factors to prognosis of posterior apical surgery. J Endod 1991;17:239–41. 9. Rubinstein RA, Kim S. Long-term follow-up of cases considered healed one year after apical microsurgery. J Endod 2002;28:378–83. 10. von Arx T, Jensen SS, Hanni S. Clinical and radiographic assessment of various predictors for healing outcome 1 year after periapical surgery. J Endod 2007;33:123–8. 11. von Arx T, Jensen SS, H€anni S, et al. Five-year longitudinal assessment of the prognosis of apical microsurgery. J Endod 2012;38:570–9. 12. Song M, Jung IY, Lee SJ, et al. Prognostic factors for clinical outcomes in endodontic microsurgery: a retrospective study. J Endod 2011;37:927–33. 13. Kim S, Pecora G, Rubinstein R. Comparison of traditional and microsurgery in endodontics. In: Kim S, Pecora G, Rubinstein R, eds. Color Atlas of Microsurgery in Endodontics. Philadelphia: Saunders; 2001. 14. Kim S, Kratchman S. Modern endodontic surgery concepts and practice: a review. J Endod 2006;32:601–23.
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Clinical Research 15. Molven O, Halse A, Grung B. Incomplete healing (scar tissue) after periapical surgery—radiographic findings 8 to 12 years after treatment. J Endod 1996;22: 264–8. 16. Molven O, Halse A, Grung B. Observer strategy and the radiographic classification of healing after endodontic surgery. Int J Oral Maxillofac Surg 1987;16:432–9. 17. Zuolo ML, Ferreira MO, Gutmann JL. Prognosis in periradicular surgery: a clinical prospective study. Int Endod J 2000;33:91–8. 18. Desvarieux M, Schwahn C, Volzke H, et al. Gender differences in the relationship between periodontal disease, tooth loss, and atherosclerosis. Stroke 2004;35:2029–35. 19. Marquis VL, Dao T, Farzaneh M, et al. Treatment outcome in endodontics: the Toronto Study. Phase III: initial treatment. J Endod 2006;32:299–306. 20. McAbee J, Li Q, Yu H, et al. Sexual dimorphism in periapical inflammation and bone loss from mitogen-activated protein kinase phosphatase-1 deficient mice. J Endod 2012;38:1097–100. 21. Lindeboom JA, Frenken JW, Kroon FH, et al. A comparative prospective randomized clinical study of MTA and IRM as root-end filling materials in single-rooted teeth in endodontic surgery. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;100:495–500. 22. Taschieri S, Del Fabbro M, Testori T, et al. Endodontic surgery with ultrasonic retrotips: one-year follow-up. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005; 100:380–7. 23. Taschieri S, Del Fabbro M, Testori T, et al. Microscope versus endoscope in rootend management: a randomized controlled study. Int J Oral Maxillofac Surg 2008; 37:1022–6.
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24. Friedman S. Treatment outcome and prognosis of endodontic therapy. In: Ørstavik D, Pitt Ford TR, eds. Essential Endodontology: Prevention and Treatment of Apical Periodontitis. Oxford: Blackwell Science; 1998:368–9. 25. Song M, Kim E. Success and failure of endodontic microsurgery. J Kor Acad Cons Dent 2011;36:465–76. 26. Hirsch JM, Ahlstrom U, Henrikson PA, et al. Int J Oral Surg 1979;8:173–85. 27. Friedman S. Treatment Outcome and Prognosis of Endodontic Therapy. 2nd ed. Malden, MA: Blackwell Science; 2008. 28. Dietrich T, Zunker P, Dietrich D, et al. Periapical and periodontal healing after osseous grafting and guided tissue regeneration treatment of apicomarginal defects in periradicular surgery: results after 12 months. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;95:474–82. 29. Rosenstiel SF, Land MF, Fujimoto J. Contemporary Fixed Prosthodontics. St Louis, MO: Mosby Elsevier; 2006. 30. Shillingburg HT, Sather DA, Stone SE. Fundamentals of Fixed Prosthodontics. Chicago: Quintessence Publishing; 1997. 31. Duncan HF, Pitt Ford TR. The potential association between smoking and endodontic disease. Int Endod J 2006;39:843–54. 32. W-Dahl A, Toksvig-Larsen S. Cigarette smoking delays bone healing: a prospective study of 200 patients operated on by the hemicallotasis technique. Acta Orthop Scand 2004;75:347–51. 33. Chang LD, Buncke G, Slezak S, et al. Cigarette smoking, plastic surgery, and microsurgery. J Reconstr Microsurg 1996;12:467–74.
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Prognostic Factors of Clinical Outcomes in Endodontic Microsurgery: A Prospective Study Minju Song, DDS, MSD, PhD,* Sahng Gyoon Kim, DDS, MS,† Seung-Jong Lee, DDS, MS, PhD,‡ Baekil Kim, DDS, MSD, PhD,§ and Euiseong Kim, DDS, MSD, PhD‡ Abstract Introduction: This prospective study examined the potential prognostic factors of endodontic microsurgery and compared the predictors of an isolated endodontic lesion with those of both an isolated endodontic lesion and an endodontic-periodontal lesion. Methods: Data were collected from the Microscope Center of the Department of Conservative Dentistry at the Dental College of Yonsei University, Seoul, Korea, between March 2001 and March 2011. A total number of 584 teeth were included, and all clinical procedures were performed by a single operator (E.K.). The evaluation was performed at least 1 year after surgery. For statistical analysis of the predisposing factors, the chi-square test and logistic regression were performed. Results: Of the 584 cases treated, 431 cases came for recall after a period of at least 12 months. Sex (female), tooth position (anterior), arch type (maxilla), and lesion type (isolated endodontic lesion) were found to have a positive effect on surgical outcome. With regards to isolated endodontic lesions, the tooth position (anterior), arch type (maxilla), and type of restoration (single/splinted crown, short bridge, and removable partial denture abutment) were found to be pure positive predictors. Conclusions: In endodontic microsurgery, it is likely that preoperative factors, particularly the tooth position and arch type, have a greater influence on the healing outcome than intra- and postoperative factors. (J Endod 2013;39:1491–1497)
Key Words Endodontic microsurgery, healing outcome, prognostic factors, prospective clinical study, tooth position
B
efore the advent of surgical operating microscopes, the success rates of traditional endodontic surgery ranged from 43% to 75% (1), which is lower than those of nonsurgical retreatments (2). However, root-end surgery has changed radically over the last 20 years with the implementation of microsurgical techniques and the use of advanced equipment. In recent years, endodontic microsurgery including the use of high-power illumination and magnification (10 and higher), ultrasonic root-end preparation, and biocompatible root-end filling materials has produced favorable outcomes in the 90% success rate range (1, 3). Several studies have reported on the prognostic factors for apical surgery, which are not classified according to the type of surgical technique such as traditional rootend surgery, contemporary root-end surgery, and endodontic microsurgery (4–6). Numerous authors have analyzed the effects of individual variables on the outcome of endodontic surgery. Most predictable preoperative prognostic factors in many studies include the length and quality of existing root filling, the presence of preoperative lesion, the presence of post and the lesion size. The intraoperative factors include the placement of root-end filling, the root-end preparation methods, the root-end filling materials, and the operator’s skill. The postoperative factors include the apical and coronal seal (4–8). In the past decade, many studies have reported on the clinical outcomes of endodontic microsurgery (3, 9, 10). However, there are only a few reports related to the prognostic factors of endodontic microsurgery. Von Arx et al (10) evaluated the influence of various predictors on healing outcome 1 year after endodontic microsurgery with 194 teeth (10). Using logistic regression, the pain at initial examination (P = .04) was the only predictor reaching significance. In another study by von Arx et al (11) that assessed the 5-year outcome and its predictors in a cohort for which the 1-year outcome was reported, 2 significant outcome predictors were found: a mesial-distal bone level at #3 mm versus >3 mm from the cementoenamel junction (78.2% vs 52.9%, P < .02) and root-end filling with ProRoot MTA (Dentsply, Tulsa, OK) versus Super EBA (Harry J. Bosworth, Skokie, IL) (86.4% vs 67.3%, P < .004). In our previous retrospective study (12), the potential prognostic factors for endodontic microsurgery were sex (female), tooth position (anterior), lesion type (isolated endodontic lesion) and root-end filling material (ProRoot MTA and Super EBA). When periodontally involved lesions were excluded, an isolated endodontic lesion might reduce the effects of many variables. The tooth position (anterior) was found to be a pure predictor of an endodontic lesion affecting the clinical outcome. However, prognostic factors have been rarely reported for endodontic microsurgery, and more research is needed. This prospective study examined the potential prognostic
From the *Department of Conservative Dentistry, Gangnam Severance Dental Hospital, †Division of Endodontics, College of Dental Medicine, Columbia University, New York, New York; ‡Microscope Center, Department of Conservative Dentistry and Oral Science Research Center, College of Dentistry, Yonsei University, Seoul, Korea; and §Department of Preventive Dentistry and Public Oral Health, College of Dentistry, Yonsei University, Seoul, Korea. Supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010-0021281). Address requests for reprints to Dr Euiseong Kim, Microscope Center, Department of Conservative Dentistry and Oral Science Research Center, College of Dentistry, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu, Seoul 120-752, South Korea. 0099-2399/$ - see front matter Copyright ª 2013 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2013.08.026
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Clinical Research factors for the outcome of endodontic microsurgery and compared the predictors for isolated endodontic lesions with those of both isolated endodontic lesions and endodontic-periodontal lesions.
Methods Case Selection This study was approved by the Yonsei Dental College, Yonsei University Institutional Review Board (number 2001–2), and informed consent was acquired from all participants. Data were collected from the Microscope Center of the Department of Conservative Dentistry at the Dental College, Yonsei University, Seoul, Korea, between March 2001 and March 2011. Teeth with a mobility class II or greater, horizontal and vertical fractures, and perforation were excluded from the study. A total number of 584 teeth requiring endodontic surgery were included in the study. Surgical Procedure All clinical procedures were performed according to the Yonsei protocol described in a previous study (12) and were performed by a single operator (E.K.). With the exception of the incisions, flap elevation, and suturing, all surgical procedures were performed using a surgical operating microscope (OPMI PICO; Carl Zeiss, G€ottingen, Germany). Patients were anesthetized with 2% lidocaine with 1:80,000 epinephrine, and sulcular or mucogingival incisions were chosen depending on the type and esthetic requirements of the case. For additional hemostasis during surgery, cotton pellets soaked in 0.1% epinephrine (Bosmin; JeilInc, Seoul, Korea) and/or ferric sulfate (Astringedent; Ultradent Products, Inc, South Jordan, UT) were applied topically as required. The tissue was gently reflected toward the apical area with a Molten 2–4 curette (G Hartzell and Son Inc, Concord, CA). In cases with mandibular second premolars or first molars, the mental foramen was identified by reflecting a vertical incision that was placed mesially to the first premolar. A KP1 retractor (G Hartzell and Son Inc) was then placed just coronal to the mental foramen, and a 1.5-cm-long and 2-mm-deep groove was made by using a Lindemann bur (7, 13). This groove was designed to protect the mental foramen during the surgical procedure by creating a rest for the serrated end of the retractor. Osteotomies were performed with an H161 Lindemann bone cutter (Brasseler, Savannah, GA) in an Impact Air 45 handpiece (Palisades Dental, Englewood, NJ). A Columbia 13–14 curette (G Hartzell and Son Inc) and a Jacquette 34/35 scaler (G Hartzell and Son Inc) were used for periradicular curettage. A 2- to 3-mm root tip with a 0 to 10 beveled angle was resected with a 170-tapered fissure bur under copious sterile distilled water irrigation. The resected root surface was then stained with methylene blue and inspected with a micromirror under 20 to 26 magnification to examine the entire root tip resection and to search for anatomic details. Root-end preparation extending 3 mm into the canal space along the long axis of the root was made with KIS ultrasonic tips (Obtura Spartan, Fenton, MO) driven by a piezoelectric ultrasonic unit (Spartan MTS, Obtura Spartan). Isthmuses, fins, and other significant anatomic irregularities were identified and prepared with the ultrasonic instruments. After the root-end preparation was completed, the prepared cavity was inspected with a micromirror at a high magnification (20–26) to ensure that no debris existed in the root-end preparation. The prepared root-end cavity was dried with a Stropko irrigator/drier (Obtura Spartan). The root-end filling material used was Intermediate Restorative Material (IRM; Caulk Dentsply, Milford, DE), Super EBA, or ProRoot MTA. The adaptation of the filling material to the canal apical walls was confirmed with the aid of an operating microscope at high magnifica1492
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tion. A postoperative radiograph was taken to verify correct placement and an absence of excess material in the bony crypt, and the flap was closed and sutured with 5 0 monofilament sutures. A postoperative mouthwash (0.2% chlorhexidine gluconate [Hexamedin; Bukwang Phar Co, Ansan, Korea]) was commonly prescribed, and the sutures were removed 4–7 days later. After surgery, an operation record form was made with the preoperative and intraoperative factors from the patient records and periapical radiographs. The operation record form was updated with the postoperative events whenever the patients were recalled periodically to assess the clinical and radiographic signs of healing.
Evaluation Factors Evaluation factors were divided into preoperative, intraoperative, and postoperative factors similar to the previous retrospective study (12). The preoperative factors included the patients’ age and sex, tooth position, arch type, preoperative signs and/or symptoms, probing depth, root filling state (length, density, material), type of root canal treatment (initial treatment, retreatment), history of apical surgery, type of a preoperative restoration, and lesion type. The intraoperative factors included the root-end filling material, the presence of complications such as sinus wall perforation or nerve damage, and the presence of a ‘‘through-and-through’’ lesion. The postoperative factors included the type of postoperative restoration at follow-up. The preoperative signs and/or symptoms were defined as preoperative pain or swelling. The adequate root filling length was defined as a filling within 2 mm from the apex, and the criterion for adequate density was a filling without voids and with uniform radiopacity. The lesion type was divided into isolated endodontic lesions (class A, B, or C) and endodontic-periodontal combined lesions (class D, E, or F) as classified by Kim and Kratchman (14). The type of preoperative and postoperative restoration was divided into 4 subgroups: single/splinted crown, short bridge, long bridge, and removable partial denture (RPD) abutment. Resin cores in the anterior teeth were included in the single/splinted crown subgroup. A short bridge was defined as having less pontics than abutments. A long bridge was defined as having the same number of pontics or more pontics than abutments. Regardless of the type of restoration, if the tooth was used as an abutment for an RPD, it was categorized as an RPD abutment. All data were recorded on the operation record form by a single doctor, except for the radiographic interpretations in which 2 examiners had to concur. Radiographic interpretation included root filling density and root filling length. Clinical and Radiographic Evaluation The patients were usually followed up at 3, 6, and 12 months and every year thereafter. On every recall visit, a routine examination was performed, and periapical radiographs were taken. The clinical data, including the signs and/or symptoms or loss of function, tenderness to percussion or palpation, subjective discomfort, mobility, sinus tract formation or periodontal pocket formation, postoperative complications, and type of restoration at follow-ups, were included in the operation record form. The evaluation was performed at least 1 year after surgery. The postoperative radiographs were evaluated independently by 2 examiners using the same criteria used by Molven et al (15, 16). The healing classifications were as follows: 1. 2. 3. 4.
Complete healing: The re-establishment of the lamina dura Incomplete healing: Scar tissue Uncertain healing Unsatisfactory healing JOE — Volume 39, Number 12, December 2013
Clinical Research Assessment of Outcome Healing was judged clinically and radiographically. The criteria for a successful outcome included the absence of clinical signs and/or symptoms and radiographic evidence of complete or incomplete healing. The criteria for failure included any clinical signs and/or symptoms or radiographic evidence of uncertain or unsatisfactory healing. Analyses of Data For statistical analysis of the predisposing factors, the dichotomous outcome (success or failure) was used as the dependent variable. A univariate description with the percentage frequencies was generated to characterize the study material. Significant associations between the outcome and all the variables were examined using chi-square tests or Fisher exact tests to identify the potential outcome predisposing factors. Multiple analyses of the predisposing factors using logistic regression models were performed. All statistical analyses were performed with SPSS v19.0 software (IBM Corp, Somers, NY), and the level of significance was set at P < .05.
Of the 584 cases treated, 431 cases came for recall after a period of at least 12 months. A recall rate of 73.8% (431/584) was achieved. Table 1 presents the distribution of cases in relation to the recall period. Table 2 lists the distribution of the cases according to the variables/category and bivariate analysis. The Cohen kappa value for the density and length of pre-existing root filling as well as postoperative radiographs ranged from 0.87–0.95 (Table 3). Of the preoperative factors examined, significant differences were observed for age (P < .001), sex (P = .027), tooth position (P = .002), arch type (P = .002), and lesion type (P = .001) with regards to both isolated endodontic lesions and endodontic-periodontal lesions (Table 2). Of the intraoperative and postoperative factors, none were found to be significant (P > .05). Of the 431 cases recalled, 87 cases were related to endodontic-periodontal combined lesions, and 344 cases were related to isolated endodontic lesions. With regards to the isolated endodontic lesions, the age (P = .005), tooth position (P = .006), and arch type (P = .002) were found to be significant among the preoperative factors. The type of postoperative restoration (P = .023) was also found to be significant (Table 2). As with the previous results of the retrospective study (12), variables with a significance level of 0.05 or less were included in the logistic regression model. Table 4 lists the point estimate, 95% confidence intervals of the odds ratios, and the P value of the significant remaining parameters. For both isolated endodontic lesions and endodonticperiodontal lesions, sex (female), tooth position (anterior), arch type (maxilla), and lesion type (endodontic lesion) were found to have a positive effect on the outcome. On the other hand, with the isolated endodontic lesions, the tooth position (anterior) and arch type TABLE 1. Distribution of Cases Related to the Recall Period 1 year 2 years 3 years 4 years 5 years 6 years 7 years 8 years 9 years 10 years
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Discussion This study aimed to identify the significant prognostic factors in endodontic microsurgery that can guide us in the hope of achieving higher success rates. The prognostic factors should be considered in case selection because the treatment outcome may depend on them. As with our previous retrospective study (12), similar evaluation factors were investigated in this prospective study. The results of this study indicate that several factors, including age, sex, tooth position, arch type, lesion type, and type of postoperative restoration, had a significant effect on the healing outcome of endodontic microsurgery. It appears that the preoperative factors, particularly the tooth position and arch type, had a greater effect on the healing outcome than the intra- and postoperative factors.
Age
Results
Recall period
(maxilla) were significant (Table 4). The type of postoperative restoration (long bridge) was found to have a negative effect on the outcome (P = .022).
No. of teeth (%) 110 (18.8) 120 (20.7) 40 (6.8) 37 (6.3) 18 (3.1) 27 (4.6) 23 (3.9) 30 (5.1) 23 (3.9) 3 (0.5)
In many studies, the patients’ age has had no significant effect on the treatment outcome (7, 17). However, Barone et al (5) reported that the rate of healing in patients older than 45 years was 84% compared with 68% for younger patients. On the other hand, in the present study, the highest success rate was reported in patients under 20 years and tended to decrease as the patients aged (P < .05). Perhaps this can be attributed to the younger patients having a better healing potential. This result should be interpreted with caution because the cutoff age for statistical analysis varies among studies.
Sex This study indicated that males had a poorer success rate than females. In the periodontal literature, it has been shown that males are more prone to periodontal infection than females (18). In an endodontic outcome study (19), it was shown that male patients had a significantly lower success rate after initial root canal treatment when compared with female patients. In a mouse experimental study of pathologic endodontic bone loss, male mice suffered more bone loss with the increase in inflammatory infiltrate (20). However, the clinical significance of sexual dimorphism in periapical inflammation and wound healing has not been fully elucidated.
Tooth Position and Arch Type There are a few studies on apical surgery in which tooth position was not significant on the healing outcome of endodontic surgery (17, 21, 22). A few studies have investigated the outcomes of endodontic microsurgery per tooth group, but they were just descriptions without statistical analysis (9, 23). In this prospective study, the anterior, premolar, and molar teeth had significantly different success rates with microsurgery (P < .05). A significant difference was also observed between the maxillary and mandibular groups (P < .05). In addition, the success rates were analyzed according to the tooth position within the jaw. Within the mandible, there was no significant difference found in the success rate among the tooth positions. However, within the maxilla, the success rates differed according to tooth position (P < .001). The maxillary anterior teeth tended to have a higher success rate than the other tooth groups (14), which might be because of the relatively easy access and less complicated root anatomy (24). The use of a surgical operating microscope does not enhance access (25). The lower success rates in lower anterior and molar teeth compared with upper anterior teeth may be Prognostic Factors in Endodontic Microsurgery
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Endo + endo-perio
Song et al.
Variables/category
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Age <20 21–30 31–40 41–50 51–60 >60 Sex Male Female Tooth position Anterior Premolar Molar Arch type Maxilla Mandible Right vs left Right Left Preoperative signs and symptoms No Yes Probing depth #4 mm 5–7 mm $8 mm Root filling length Adequate Inadequate Root filling density Adequate Inadequate Root filling material Empty Gutta-percha Other Previous treatment Initial Retreatment Previous apical surgery No Yes Preoperative restoration type Single/splinted crown Short bridge Long bridge RPD abutment Lesion type Endodontic
Success, n (%)
Failure, n (%)
15 (100.0) 87 (92.6) 108 (92.3) 67 (78.8) 63 (86.3) 29 (61.7)
0 (0.0) 7 (7.4) 9 (7.7) 18 (21.2) 10 (13.7) 16 (38.3)
136 (81.0) 233 (88.6)
32 (19.0) 30 (11.4)
208 (91.2) 69 (80.2) 92 (78.6)
20 (8.8) 17 (19.8) 25 (21.4)
272 (88.9) 97 (77.6)
34 (11.1) 28 (22.4)
155 (87.6) 214 (84.3)
22 (12.4) 40 (15.7)
50 (86.2) 319 (85.5)
8 (13.8) 54 (14.5)
305 (86.9) 30 (78.9) 34 (81.0)
46 (13.1) 8 (21.1) 8 (19.0)
172 (83.5) 149 (90.3)
34 (16.5) 16 (9.7)
185 (84.5) 136 (89.5)
34 (15.5) 16 (10.5)
36 (87.8) 280 (86.4) 5 (83.3)
5 (12.2) 44 (13.6) 1 (16.7)
272 (86.3) 49 (87.5)
43 (13.7) 7 (12.5)
322 (86.6) 47 (79.7)
50 (13.4) 12 (20.3)
311 (85.4) 31 (93.9) 13 (72.2) 14 (87.5)
53 (14.6) 2 (6.1) 5 (27.8) 2 (12.5)
304 (88.4)
40 (11.6)
Endo
Chi-square value
P value
30.529
.000
Success, n (%) 13 (100.0) 67 (93.1) 90 (94.7) 60 (83.3) 47 (85.5) 27 (73.0)
4.860 12.487
9.183 0.993 0.019 2.580
3.641 0.923 0.410
0.054 1.968 4.322
10.520
Failure, n (%)
Chi-square value
P value
16.067
.005
0.605
.437
10.342
.006
9.610
.002
0.531
.466
0.080
.778
1.436
.529
0.160
.689
0.102
.750
0.668
.726
0 (0.0) 5 (6.9) 5 (5.3) 12 (16.7) 8 (14.5) 10 (27.0)
.027 110 (86.6) 194 (89.4)
17 (13.4) 23 (10.6)
180 (93.3) 54 (83.1) 70 (81.4)
13 (6.7) 11 (16.9) 16 (18.6)
230 (91.6) 74 (79.6)
21 (8.4) 19 (20.4)
126 (86.9) 178 (89.4)
19 (13.1) 21 (10.6)
43 (89.6) 261 (88.2)
5 (10.4) 35 (11.8)
273 (88.6) 24 (88.9) 7 (77.8)
35 (11.4) 3 (11.1) 2 (22.2)
145 (88.4) 124 (89.9)
19 (11.6) 14 (10.1)
147 (88.6) 122 (89.7)
19 (11.4) 14 (10.3)
30 (85.7) 235 (89.4) 4 (100.0)
5 (14.3) 28 (10.6) 0 (0.0)
234 (88.6) 35 (92.1)
30 (11.4) 3 (7.9)
270 (89.1) 34 (82.9)
33 (10.9) 7 (17.1)
256 (88.3) 25 (100.0) 12 (75.0) 11 (84.6)
34 (11.7) 0 (0.0) 4 (25.0) 2 (15.4)
.002
.002 .334 .890 .275
.056 .166 .921
.816
.781
.161
.295
.208
.001
6.728
.053
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TABLE 2. Distribution of Cases per Variables/Category and Bivariate Analysis
TABLE 3. Interexaminer Reliability in Evaluating Preoperative and Postoperative Radiographs
.023
1.000
1.000
.529
.616
Clinical Research
Factors
8.730
0.894
1.274
Root filling density Root filling length Postoperative radiographs
Agreement (%)
Cohen kappa value
97.57 96.23 97.22
0.95 0.92 0.87
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Endo, isolated endodontic lesion; Endo + endo-perio, both isolated endodontic lesion and endodontic-periodontal lesion; MTA, mineral trioxide aggregate; RPD, removable partial denture.
34 (12.1) 0 (0.0) 4 (25.0) 2 (15.4) 311 (85.4) 31 (93.9) 13 (72.2) 14 (87.5)
53 (14.6) 2 (6.1) 5 (27.8) 2 (12.5)
4.322
.208
1.000 59 (14.5) 3 (12.0) 347 (85.5) 22 (88.0)
354 (85.5) 15 (88.2)
60 (14.5) 2 (11.8)
0.327 29 (14.8) 31 (13.9) 2 (16.7) 167 (85.2) 192 (86.1) 10 (83.3)
22 (25.3)
Endodontic-periodontal Lesion type (endodontic lesion) A B C Root-end filling material MTA Super EBA IRM Complication Absence Presence Through-and-through lesion No Yes Postoperative restoration type Single/splinted crown Short bridge Long bridge RPD abutment
65 (74.7)
247 (87.9) 34 (100.0) 12 (75.0) 11 (84.6)
38 (11.8) 2 (9.5) 285 (88.2) 19 (90.5)
39 (11.8) 1 (7.7) 292 (88.2) 12 (92.3) 1.000
.835
45 (91.8) 161 (89.0) 98 (86.0)
135 (90.0) 162 (87.1) 7 (87.5)
4 (8.2) 20 (11.0) 16 (14.0)
15 (10.0) 24 (12.9) 1 (12.5)
attributed to limited access that can potentially hinder the precise surgical procedures.
Lesion Type In this prospective study, the lesion type was a significant predictor (95% confidence interval, 1.120–3.793, P = .020). The isolated endodontic lesion had a higher success rate than the endodonticperiodontal combined lesion (88.4% vs 74.7%). A similar pattern was reported in our previous study (12), and several studies have also suggested a poorer prognosis for teeth with periodontally involved lesions (3, 26). The loss of alveolar bone induces the apical migration of gingival epithelial cells that forms a long junctional epithelium, making periodontal reattachment difficult. The long junctional epithelium may serve as a path for reinfection and prevent the healing process (27). Therefore, in situations of endodonticperiodontal lesions, a regeneration technique such as guided tissue regeneration might be necessary to help the lesions to heal. With a combined endodontic-periodontal lesion, the prognosis of the teeth may depend on secondary periodontal support in addition to the endodontic microsurgery (28). Therefore, the predisposing factors of an isolated endodontic lesion after endodontic microsurgery would be different from those of an endodontic-periodontal lesion. Age (P < .001), sex (P = .027), tooth position (P = .002), arch type (P = .002), and lesion type (P = .001) were found to be significant predictors of success for combined lesions, whereas age (P = .005), tooth position (P = .006), arch type (P = .002), and type of postoperative restoration (P = .023) were found to be significant for isolated endodontic lesions. Tooth position (anterior) and arch type (maxilla) seemed to be important positive predictors of surgical success (logistic regression, P < .05) for isolated endodontic lesions. Type of Postoperative Restoration In the present study, teeth restored with single/splinted crowns presented a higher healing rate than teeth restored with long bridges (95% confidence interval, 1.246–17.382, P = .022). A long bridge was defined as a restoration in which the number of pontics is the same or more than the number of abutments. In fixed prosthodontics with several pontics, the ability of the abutment teeth to resist applied forces is important for the prognosis (29). Endodontic microsurgery leaves shorter roots after root-end surgery, which can lead to an unfavorable outcome based on Ante’s law, which suggests that when the root surface area of the abutment is less than the root surface area of the teeth being replaced, fixed prosthodontics should not be placed (30). Moreover, with overloading of abutments with a long span, it might be hard for the root-end filling materials of the abutments to bear the occlusal force and thus fail to form a bacteria-tight seal. Other Factors Other preoperative factors associated with previous treatment status such as root filling state (length, density, materials), type of Prognostic Factors in Endodontic Microsurgery
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Clinical Research TABLE 4. Logistic Regression Model Endo + endo-perio
Endo
95% confidence interval Variables Sex Female versus male Tooth position Anterior versus premolar Anterior versus molar Arch type Maxilla versus mandible Lesion type Endodontic versus endodonticperiodontal Postoperative restoration type Single vs short bridge Single vs long bridge Single versus RPD abutment
95% confidence interval
Point estimate
Lower
Upper
P value
Point estimate
Lower
Upper
P value
1.926
1.090
3.403
.024
1.489
0.733
3.027
.271
2.176
1.057
4.479
.035
3.060
1.210
7.739
.018
2.288
1.154
4.537
.018
3.445
1.407
8.437
.007
1.922
1.059
3.485
.032
2.118
1.024
4.381
.043
2.061
1.120
3.793
.020
0.000 4.653 1.330
0.000 1.246 0.253
0.000 17.382 6.976
.998 .022 .736
Endo, isolated endodontic lesion; Endo + endo-perio, both isolated endodontic lesion and endodontic-periodontal lesion; RPD, removable partial denture. The coefficient of determination = 0.115 (total) and the coefficient of determination = 0.157 (isolated endodontic lesion).
previous treatment (initial treatment or retreatment), and history of apical surgery did not have a significant relationship with healing outcome. Furthermore, of the intraoperative and postoperative factors, none was found to be significant (P > .05) except for the type of postoperative restoration. Endodontic microsurgery uses a surgical operating microscope to allow clinicians to identify and address the causes of endodontic failure. Therefore, with the strict application of microsurgical techniques, the variables related to previous treatment status and procedures may not have a significant effect on the outcome of endodontic microsurgery. Smoking habits were not evaluated in the present study but might be related to the healing process. There is a paucity of evidence relating smoking to endodontic disease, but smoking has been suggested to be related to a potential increase in surgical complications (31). Smoking is likely to affect healing in surgical endodontic cases that involve bony and soft-tissue healing (32, 33). The present study did not include the habit of smoking as an evaluation factor, and, therefore, any correlation between healing and smoking could not be analyzed. Further studies are needed to assess the relationship between smoking and healing. In this prospective study, endodontic microsurgery reduced the effect of many variables in the healing outcome compared with traditional root-end surgery. This is consistent with our previous retrospective study (12). Our 2 studies showed that age, sex, tooth position, lesion type, and postoperative restoration were important predictors. Other variables, including the root filling length and root-end filling material, were not found to be significant in this prospective study, but they were significant in the retrospective study. In conclusion, the potential positive prognostic factors on the surgical outcome with regards to both isolated endodontic lesions and endodontic-periodontal lesions include sex (female), tooth position (anterior), arch type (maxilla), and lesion type (isolated endodontic lesion). The tooth position (anterior), arch type (maxilla), and type of restoration (single/splinted crown, short bridge, and RPD abutment) were found to be positive predictors for clinical outcome of an isolated endodontic lesion. More prospective studies need to be performed to further investigate the effects of various prog1496
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nostic factors including the effect of smoking on the healing outcome of endodontic microsurgery.
Acknowledgments The authors deny any conflicts of interest related to this study.
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