prognosis of luxated permanent teeth — the development of pulp necrosis

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Prognosis of luxated permanent teeth - the development of pulp necrosisAtidreasen EM, Vestergaard Pedersen B. Prognosis of luxated permanent teeth - tbe development of pulp necrosis. Endod lDent Traumatol 1985; 1: 207-220. Abstract - A population of 400 patients, eomprising 637 luxated p e r m a n e n t teeth was studied prospeetively with respect to the development of pulp necrosis after luxation injuries. The patients w e r e treated for traumatic dental injuries over a period of 10 years. While initial treatment was provided according to established treattnent guidelines by the attending oral surgeoti at the emergency room, foUow-tip examination and treatment was prov i d e d by one oral surgeon. It ap]3eared th;tt pulp necrosis occtn-red s o o n after injury, within 3 tnonths after conctission, wilhin (he 1st yr after subluxation and extrusion, and might be diagnosed u p to 2 yr after lateral- and intrtisive ltixatioti. While tnany factors, when considered one at a tintc, were Ibund to have a signifteant or nearly significant ellect on the devclo]imcnt o( ptilp necrosis (i.e. type of injtn-y, age of jxttient, stage of root developm e n t , degree of dislocation, reducli(3n/rc|3ositioning j^roccdurc, t y p e of fixation, restorations in place at the lime of injtiry), a mullivariate regression analysis revealed lluil when ihe type of injury (diagnosis) and stage of f o o t development were taken i n t o account, (he elfecl of other factors was no longer significant. "riie risk of pulp neerosis increased witfi the extent of injury, i.e. concussion and subluxation represented the least risk, followed i n ascetiding order by extrusive-, lateral-, and ititrusive luxa t i o n . Moreover, teeth wilfi (om|)letcd root formation detnons t r a t e d a greater risk of pul]5 necrosis than teeth witfi iticotnplete r o o t fbrmation. No treattnent effect could be demonstrated. However, as treatment was perfortned accotding to established guidelines, which might introduce bias, it would appear justifted to c o n d u c t randomized elinieal sttidies in oider to determine the v a l u e of different forms of treatment (e.g. reduction and ftxation o f luxated teeth) to improve tlie prognosis with respect to the development of pulp necrosis after injury. In conclusion, the m a j o r faetors influencing dcveloi^ment of pul]3 necrosis after hixa t i o n injuries appear to be the extent of the initial injury to the p u l p and periodontium, as reflected by the type of luxation, a n d the repair potential of the injtu'ed tooth, as reflected by the s t a g e of root dcvefoi^ment.

Frances iVI. Andreasen* and Bo Vestergaard Pedersen**'Department of Oral Medicine and Oral Surgery, University Hospital (Rigshospitalet), and Department of Pedodontics, Royal Denial College, Copenhagen. "Statistical Research Unit, Copenhagen University and the Danish Breast Cancer Cooperative Group, Finsen Institute, Copenhagen, Denmark

Key words: luxation injuries, prognosis, pulp necrosis, root development, proportional hazards regression model, grouped survival data. R M. Andreasen, nD.S., Department of Oral Medicine and Oral Surgery, University Hospifal (Rigshospitalet), Tagensvej 18, DK 2200 Copenhagen N, Denmark. Accepted for publication 13 May 1985.

Desj^ite many chnical and experinienlal sltidies, the etiology of pulp tiecrosis after luxation injuries is still uncertain (1 14). The general outcome of these investigations has been the idetitiflcation of clinical factors wliich, (o a greater or lesser degree, were f o u n d to \)c associated with the developtnent of pttlp

neci'osis after injury. These factors include: age of the patient (1, 3, 8, 9), stage of root development (1, 3, 5 12, 27), type of luxation injury (3, 6, 8, 9, 11, 12, 27), mobility of the injured tooth at the time ofinjtiry (1, 2, 6, 8, 13), degree of dislocation (14), initial positive reaction to pulp testing (1, 5, 6, 13),


Andreasen and Pedersen

tenderness to percussion at the time of injury (13, 15), the type of reduction procedure (2, 16), fixation period (2), and delayed initial treatment (1, 5, 6, 8). These results imply a rather complex etiology of pulp neerosis after luxation injuries. However, in many of these studies, only the Jrequency of pulp necrosis in relation to one factor at a time was studied. Sueh analyses neglect the time from injury to occurrence of pulp necrosis and cannot account for the possible close associations between factors studied, sueh as between age and root development or mobility and displacement of an injured tooth and the type of luxation. A multivariate analysis is required to identify the smallest set of factors whicfi contains the greatest amount of prognostie information with respeet to development of pulp necrosis after luxation injuries. It is therefore the aim of the present investigation to answer the following questions using a population of patients whieh has been uniformly treated for luxation injuries to the permanent dentition and followed prospeetively for up to 10 yr: 1. Which types of luxation injuries are followed l)y pulp neerosis and to what extent? 2. What is the chronologieal relationship between type of luxation injury and the diagnosis of pulp necrosis? 3. Wfiich factors associated with injury or subsequent treatment determine the development of pulp necrosis alter ltjxation injuries?Material and methods Material

Table 1. Distribution of luxation injuries according to type of luxafion and stage of root development. Numbers In parentheses indicate fhe number of teeth which developed pulp necrosis after injury. Luxation type Concussion Subluxafion Extrusion Lateral luxafion Intrusion Total Open apex 58 (0) 130 (0) 33 (3) 34(3) 24(15) 279 (21) Closed apex 120 (5) 93 (14) 20 (11) 88 (68) 37 (37) 358 (135) Total 178(5) 223 (14) 53 (14) 122 (71) 61 (52) 637 (156)

ty measured electromctrically. Pulp necrosis was occasionally associated with spontaneous pain or tenderness to percussion; but most cases were completely asymptomatic. In the present investigation, loss of electrometrie sensibility and at least one other objective sign was considered necessary before tbe diagnosis "pulp necrosis" was made. Table 2 presents a seleetion of variables registered in the present investigation, their distribution in tbe 5 luxation categories and the frec[ueiicy of pulp necrosis in each group irrespective of observation period. A more detailed discussion of these variables and their scoring were presented in a previous paper (17). A number of variables not shown in Table 2 were studied but found to have no effect on the development of pulp necrosis. These include: jarefixation period, percussion (ankylosis) tone at the time of injury, sensitivity to eold air, constant |3ain and loss of marginal bone support (i.e. |:)ci iodontal involvement) at the time of injury.Statistical methods

'fhe material eomprises 400 patients with 637 luxated teeth and 414 non-injured (control) teeth selected from 3260 referred to and treated fbr luxation injuries at the Department of Oral Medicine and Oral Surgery, University Hospital, Copenhagen. Details concerning selection of patient material, diagnostic criteria for luxation injuries and treatment l^rocedures have been described elsewhere (17). Only teeth which fulOllcd the criteria for luxation injuries (18) were admitted to the study; that is, concussion, subluxation, extrtisive luxation, lateral luxation and intrusion. lable 1 presents the distribution of teeth according to type of luxation injury and stage of root formation. 'I'he stage of root development at the time oi injury corresponds to the classification system established by Moorrees et al. (19). In the present investigation, ineomplete root formation was defined as one-, two-, three- or four-quarters' root length and open- to half-open apex; comjiletc root formation was full root length and closed apex. Criteria for the diagnosis of pulp neerosis were the following (18): grey color changes in the crown, periapical radiolueency, and loss of pulpal sensibih208

Eor each luxation category the possible elfect of a number of variables was reviewed initially by simple tabulation of the frequency of pulp necrosis irrespective of observation period using informal %' or Eisher's exact test for comparison between groups. In the subsequent analysis, the time until tbe diagnosis of pulp necrosis was taken into account. As the development of pulp necrosis is usually asymptomatic, it could only be recorded at the predetermined fbllow-up visits; the data thus took the form of grouped survival data. Univariate- and multivariate regression analysis of such data can be adequately performed by the computer program CENSTAT, as described in the statistical a]5penclix. Reductions from one model to a less eomplex one were tested by the likelihood ratio test, by which the dilTert^nce in deviances given by GENS'lAT were eomjjared to a ^c^ distribution with degrees ol freedom equal to the difference in degrees of freedom between the two models. The elinieal eourse for the individual tooth was

Pulp necrosis after luxation injuries in permanent dentitionTable 2. Distribution of feefh and relative frequency of pulp necrosis according fo luxation category and selected variables. Luxafion cafegory: Concussion Subluxation Variable Crown tracfure Scoring None Infracfion Uncomplicated Laferal luxation n % 115 56 100 11 29 11 84 58 58 57 82 -



n214 9


Extrusion % n 50 26 33 25 75 67 25


Intrusion %


33 24 7256

3 .5 83

22 30 24 5

318 24 8

718 28 44 32 50


79 10089 83 71 100 100 90 81 83 93


g 7 yr 8-11 yr 12-19 yr >20yrMale Female 11,21

8192 33 17 83 140 136 55 26 6

1224 13 12 29 32 46