Bull Tokyo Dent Coll (2017) 58(1): 65–70
Short Communication doi:10.2209/tdcpublication.2016-0016
Relationship between Time from Full Pulpotomy to Definitive Diagnosis of Vertical Root Fracture and Patient Age
Koichi Yoshino1, 2), Koji Ito2), Masahiko Kuroda2) and Naoki Sugihara1) 1)Department of Epidemiology and Public Health, Tokyo Dental College, 2-9-18 Misaki-cho, Chiyoda-ku, Tokyo 101-0061, Japan 2)Kyushikai, Kuroda Dental Clinic, 3-5-5-7F Uchikanda, Chiyoda-ku, Tokyo 101-0047, Japan
Received 23 May, 2016/Accepted for publication 7 July, 2016
Abstract The goal of this study was to investigate length of time between full pulpotomy and a definitive diagnosis of vertical root fracture (VRF), as well as the age at which this was made. The participants comprised 63 dental patients (40 men and 23 women) with a mean age of 65.7±10.4 years in whom a definitive diagnosis of VRF had been made between July 2013 and June 2015, and who had also undergone a full pulpotomy. The data on all these cases were obtained from 22 dental clinics belonging to a clinical study group. The mean duration between a full pulpotomy and a definitive diagnosis of VRF was 141.0±88.9 months. The results showed no differences in terms of sex, mandible/ maxilla, or tooth type. No relationship was observed between age at which the diagnosis was made and length of time between full pulpotomy and diagnosis (Pearson correlation coefficient =0.162) (p>0.05). Most diagnoses of VRF were made in patients aged over 50 years, irrespective of length of time between full pulpotomy and the diagnosis. These results suggest that age is a stronger indicator of VRF than length of time between full pulpotomy and a definitive diagnosis. Key words: Vertical root fracture — Duration of non-vital tooth — Age — Risk factor
Introduction Chrysanthakopoulos5) found that the percent- age due to RF was 4.4%. Aida et al.1) reported Recent years have seen an increase in tooth that RF accounted for 10.6% of 9,115 perma- loss due to vertical root fracture (VRF)1,5,23). nent tooth extractions in Japan. Our own Root fracture (RF), which includes VRF, is recent report23) on 736 permanent tooth becoming more prevalent as the reported extractions in 24 clinics in Tokyo found that reason for extraction of permanent teeth1,5,23). 233 of the extractions were due to VRF In a study on 2,418 teeth extracted in Greece, (31.7%). These reports suggest that VRF is
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Table 1 Number of VRFs by likely to become a matter of increasing con- age (n=63) cern for patients and dental practitioners in the near future. Age group n % Most VRFs often occur in non-vital teeth, as 30-39 2 3.2 was the case in 93.6% of extractions due to 40-49 1 1.6 VRF in our previous study23). Non-vital teeth are more prone to VRF, a phenomenon which 50-59 12 19.0 has been attributed to excessive force during 60-69 23 36.5 obturation7), the wedging effect of spreaders 70-79 22 34.9 during lateral condensation11), excessive pres- 80-89 3 4.8 sure during post cementation14,16), a decrease in dentin thickness with finger-spreaders22), and post preparation13,21). On the other hand, several reports investi- gating extractions of caries-free teeth have of the dentists had inherited the clinic from revealed a reduction in fatigue strength and their parents. The mean period of time the fracture resistance in dentin with age in labo- dentists had been practicing since graduation ratory tests2,3,8–10,15). Furthermore, some studies from dental school was 28.0±8.8 years (range, have noted an increase in the frequency of 6 to 49 years) as of April 2016. VRFs in endodontically restored teeth in patients aged over 40 years6,19,20,23). Taken 1. Data collection together, these earlier reports suggest a cor- The participating dentists were required to relation between increase in age and the inci- provide data obtained from clinical records dence of VRF. However, whether there is a on patients in whom a definitive diagnosis of relationship between duration of non-vitality VRF had been made at least once between and VRF remains to be clarified. To the best July 2013 and June 2015. All patients targeted of our knowledge, only one report to date has had also to have undergone a full pulpotomy. investigated length of time between full pulp- These conditions yielded data on 63 VRFs otomy and a diagnosis of VRF. In a study of 36 from 22 dental clinics (Table 1). The patients cases, Testori et al.20) found that the average comprised 40 men and 23 women with a elapsed time between endodontic treatment mean age of 65.7±10.4 years. The criteria for and a subsequent diagnosis of fracture was a diagnosis of VRF were “separate pieces visi- 10.8 years. ble on an X-ray” or “a fracture line extending The purpose of the present study was to from the cervical to apical regions visible in investigate length of time between full pulp- the extracted tooth”. The length of time from otomy and a definitive diagnosis of VRF, as full pulpotomy to VRF was calculated in well as the age at which this was made. months by subtracting the date of extirpation from the date of the diagnosis. The quantity of VRFs by type of tooth is shown in Table 2. Materials and Methods Twenty-eight (44.4%) of the VRFs were in the maxilla, while 35 (55.6%) were in the mandi- This was a retrospective cohort study. The ble. Vertical root fractures were identified in 6 22 participating dentists belonged to a clini- anterior teeth (9.5%), 25 premolars (39.7%), cal research organization, and all were gen- and 32 molars (50.8%). The types of prosthe- eral practitioners working out of dental offices ses used in these teeth were as follows: 29 located in the Kanto region of Japan. All the crowns (46.0%); 9 metal-ceramic bonds dental practices were established before 2006, (14.3%); 9 abutments with bridges (14.3%); 5 with the mean year of establishment being inlay fillings (7.9%); 2 resin fillings (3.2%); 1992±9.6 years (range, 1965 to 2010). Three and 9 other procedures (14.3%). Twelve 【版面】W：396 pt（片段 192 pt） H：588 pt 【本文】行数不明（手組み） 10pt 12pt【版面】W：396 pt（片段 192 送り pt） H：588 pt 【本文】行数不明（手組み） 10pt 12pt 送り 【図】●図番号・タイトル・説明：11.3Q 12.7H New Baskerville ITC 【図】●図番号・タイトル・説明：11.3Q 12.7H NewStd 図タイトルと説明のアキ 9Q ●タイトル折り返し：番号の後（続 Baskerville ITC Std 図タイトルと説明のアキ 9Q ●タイトル折り返し：番号の後（続 く説明の先頭は字下げ不要） ●図説の幅 片段：片段固定 全段：図幅 く説明の先頭は字下げ不要） ●図説の幅 片段：片段固定 全段：図幅 【表】●番号・タイトル・説明：11.3Q 12.7H New Baskerville ITC Std タイトルと表のアキ 10.5Q ●罫線 表はじめのみ双罫 表中の【表】●番号・タイトル・説明：11.3Q 12.7H New Baskerville ITC Std タイトルと表のアキ 10.5Q ●罫線 表はじめのみ双罫 表中の 罫の太さ 1.411mm ●表中：11.3Q 12.7H New Baskerville ITC Std ●脚注 11.3Q 12.7H New罫の太さ 1.411mm ●表中：11.3Q 12.7H New Baskerville ITC Std Baskerville 字下げなし ITC Std ●脚注 11.3Q 12.7H New Baskerville ITC Std 字下げなし 斜体は New Baskerville ITC Std Italic（タグは
Table 2 Number of VRFs by tooth type (n=63) Table 3 Comparison of mean length of time from full pulpotomy to VRF diagnosis by sex, Maxilla Mandible Total mandible/maxilla, and tooth type
Anterior Central 1 1 Mean duration Groups n Significance Lateral 1 1 2 (months) Canine 1 2 3 Male 40 132.7±83.6 n.s. Premolar First 6 2 8 Female 23 155.6±97.6 Second 9 8 17 Upper 28 133.7±93.5 Molar First 7 11 18 n.s. Lower 35 146.9±86.0 Second 3 11 14
Total 28 35 63 Anterior 6 200.7±77.5 Premolar 25 125.9±77.8 n.s. Molar 32 141.7±96.3
Total 63 141.0±88.9
(19.1%) of the VRF teeth had no post; 44 (69.8%) had metal posts; and 6 (9.5%) had screw posts; and 1 (1.6%) had a fiber post. Discussion 2. Statistical analysis Mean length of time from extirpation to a One limitation of this study was that, being diagnosis of VRF was compared using the a retrospective analysis, most of the data were Mann-Whitney U or Kruskal-Wallis tests. Cor- collected relatively recently. However, the relations were assessed with the Pearson cor- obtained data set did reveal that nearly all the relation coefficient. VRFs were diagnosed in patients aged over 50 years, indicating that age is a stronger factor in the development of this problem than Results duration of non-vitality. This result is in agree- ment with of those of earlier studies showing The mean length of time between full pulp- that VRFs in endodontically restored teeth otomy and a diagnosis of VRF was 141.0±88.9 become more frequent at over 40 years of months. Table 3 shows the results of this com- age6,19,20,23). The results of an earlier study by parison by sex, mandible/maxilla, and tooth this group23) also showed that the frequency of type. There were no significant differences. VRF increased in endodontically restored Figure 1 shows the relationship between teeth in patients over 45 years of age, while age at which a definitive diagnosis of VRF was Testori et al.20) showed such an increase occur- made and length of time between full pulp- ring between 45 and 60 years and Tamse19) otomy and the diagnosis. No relationship was between 41 and 60 years. found (Pearson correlation coefficient= The mean length of time between full pulp- 0.162) (p>0.05). Most of the patients were otomy and a diagnosis of VRF was 141.0±88.9 over 50 years of age at the time of diagnosis of months (11.8±7.4 years). This is consistent VRF, and this was irrespective of length of with previous reports such as that of Testori et time between full pulpotomy and the al.20), in which the length of time was reported diagnosis. to be 10.8 years. However, the standard devia- tion in our study was very large, indicating that this is too long to allow for a prospective study of a large number of cases. The notion that patient age influences VRF 【版面】W：396 pt（片段 192 pt） H：588 pt 【本文】行数不明（手組み） 10pt 12pt 送り 【図】●図番号・タイトル・説明：11.3Q 12.7H New Baskerville ITC Std 図タイトルと説明のアキ 9Q ●タイトル折り返し：番号の後（続 く説明の先頭は字下げ不要） ●図説の幅 片段：片段固定 全段：図幅 【表】●番号・タイトル・説明：11.3Q 12.7H New Baskerville ITC Std タイトルと表のアキ 10.5Q ●罫線 表はじめのみ双罫 表中の 罫の太さ 1.411mm ●表中：11.3Q 12.7H New Baskerville ITC Std ●脚注 11.3Q 12.7H New Baskerville ITC Std 字下げなし 斜体は68 New Baskerville ITC Std Italic（タグは
o f e g
A R = 0.162
60 120 180 240 300 360
Length of time (months) from pulp extirpation to VRF diagnosis Fig. 1 Relationship between age of VRF diagnosis and time from full pulpotomy to VRF diagnosis (n=63)
has been supported by several laboratory and endodontically treated teeth (mean time studies showing a reduction in fatigue since endodontic treatment: 10.5 years). strength and fracture resistance in dentin These reports indicate no differences between with age2,3,8–10,15). Bajaj et al.3) showed that fatigue vital and non-vital teeth. cracks in old dentin occurred at a lower stress However, a number of studies have found intensity level than in young dentin and prop- that endodontically treated teeth are more agated at a significantly faster rate. Ivanciket brittle when subjected to canal treatment al.8) investigated the effect of aging on resis- or post restoration procedures7,11,13,14,16,21,22). tance of human dentin to fatigue crack Mireku et al.13) used a cyclic loading test to growth. The results showed that aging of den- investigate whether patient age contributed tin was accompanied by a significant reduc- to the fracture resistance of teeth subjected to tion in resistance to initiation of fatigue crack root canal treatment and post placement. growth, as well as a significantly increased rate The results showed a significant correlation of incremental extension. However, these between fracture resistance and age, indicat- studies used dentin from extracted untreated ing that susceptibility to root fracture increases teeth (vital teeth). with age. Dentin thickness was observed to be In their investigation of differences between significantly reduced in roots that had frac- vital and non-vital teeth, Sedgley and Messer18) tured compared with in those that had not. found no differences between endodontically An earlier report by the present group23) treated teeth (mean time since endodontic showed that VRF predilection varied by tooth treatment: 10.1 years) and vital teeth in terms type. Vertical root fracture occurs at a higher of punch shear strength, toughness, or load frequency in the maxillary first and second to fracture. Papa et al.17) also found no differ- premolars, mandibular second premolars, ence in the moisture content of dentin in vital and mandibular second molars. In an investi- Time from Non-vitality to VRF and Age 69 gation of 315 cases of VRF in Chinese patients, Funding Chan et al.4) found that the incidence of VRF in mandibular first molars was twice that in This study was carried out without funding. maxillary first molars in endodontically treated teeth. It was also revealed that frac- tures occurred more often in thin, flat roots with smaller mesio-distal diameters, such as in References the mesio-buccal roots of maxillary molars and mesial roots of mandibular molars. In 1) Aida J, Ando Y, Akhter R, Aoyama H, Masui M, Morita M (2006) Reasons for permanent another report on 25 cases of VRF, Llena-Puy 12) tooth extractions in Japan. J Epidemiol 16: et al. found that maxillary second premolars 214–219. and mandibular first molars accounted for 2) Arola D, Reprogel RK (2005) Effects of aging 36% of such cases. 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