PEDIATRIC DENTISTRY/Copyright © 1986 byThe American Academy of Pediatric Dentistry

Volume 8 Number 4

Effect of trauma to primary incisors on root developmentof their permanent successors

Yerucham Zilberman, DMD

Yocheved Ben Bassat, DMD

Jehoshua Lustmann, DMD

Anna Fuks, CD

Ilana Brin, DMD

AbstractTrauma to the primary incisors may, by their displacement,

cause developmental disturbances in the root formation of thepermanent incisors. To verify this hypothesis, dental radiographsof 34 children, whose primary incisors had been previously in-jured, were evaluated. Only 6 children showed disturbances inroot development of maxillary permanent incisors. Three cases inwhich trauma to the primary dentition resulted in pathology tothe permanent dentition are presented, stressing the need for closeperiodic examination and early detection of possible develop-mental defects in the permanent dentition.

The correlation between the presence of min-

eralization defects, observed in the maxillary per-manent incisors of a group of school children, andthe history of trauma to their primary dentition, hasbeen reported. 1,2 The clinical and radiographic re-sults of these studies demonstrated that most of thechildren with affected permanent incisors experi-enced trauma prior to age 5 years and during Nolla’sdevelopmental stages 3-6 (Table 1).3

The impact of the primary roots to the devel-oping tooth at the time of the trauma may cause adeflection or displacement of the permanent succes-sors.4 The purpose of the present study was to inves-tigate the eventual effects of trauma to the primaryincisors on the root development of their permanentsuccessors.

Methods and Materials

The dental records of 34 children whose maxil-lary primary incisors had been traumatized previ-ously were selected from a larger sample.2 Only rec-ords of children whose clinical history and periapicalradiographs taken at the time of the injury did not

disclose signs of previous trauma were included. Incontrast to the previous report,2 teeth presenting withdeep carious lesions were not excluded from thepresent study, since it is doubtful that the presenceof a carious lesion in a primary crown would affectroot development of the permanent successor.

The majority of the children included in this re-port experienced trauma to their primary incisors be-tween ages 1 and 31~ years, and the most commontypes of injury recorded were palatal displacementand luxation.

Periapical radiographs taken at the time of trau-ma were evaluated for:

1. The amount of resorption of the roots of primaryincisors, and

2. The developmental stage of the permanent budsaccording to Nolla.3

Radiographic evaluation revealed that at the timeof trauma the primary teeth had fully formed rootsor were at the initial stages of root resorption. Thebuds of the permanent incisors were at Nolla’s de-velopmental stages 3-6.

One hundred twenty-nine fully erupted maxil-lary permanent incisors were examined and classi-fied into 2 groups: (1) trauma group--comprising permanent incisors which were the successors oftraumatized primary teeth; (2) nontrauma group--including 61 permanent incisors, successors to non-traumatized primary teeth (i.e., teeth located adjacentto the injured ones).

The distribution of the sample according to ageand dental development at the time of trauma wassimilar in both groups.

Standardized long-cone periapical and tangen-tial radiographs of the permanent incisors taken at arecall examination were analyzed for developmental

PEDIATRIC DENTISTRY: December 1986/Vol. 8 No. 4 289

Table 1. Stages of Dental Development (according to Nol-la)

Stage 0Stage 1Stage 2Stage 3Stage 4Stage 5Stage 6Stage 7Stage 8Stage 9Stage 10

Absence of cryptPresence of cryptInitial calcificationOne-third of crown completedTwo-thirds of crown completedCrown almost completedCrown completedOne-third of root completedTwo-thirds of root completedRoot almost completed--open apexApical end of root completed

disturbances of the roots and the surrounding boneas follows:

1. Root dilaceration in the mesiodistal and bucco-lingual dimensions

2. Arrest of root formation3. Obliteration of pulp chamber and root canal4. Severe malformation of the root or any other phe-

nomenon involving the surrounding bone.

Root dilaceration has been defined by Andreasen4

as a sharp deviation or bend of the root in relationto the long axis of the tooth. A slight distal angula-tion, frequently seen in lateral incisors, was consid-ered as normal. The dilaceration was recorded ac-cording to its location, i.e., cervical, middle, and apicalone-third of the root.

ResultsSix children (17.6%) presented with develop-

mental disturbances in the root or a pathologic con-dition in the surrounding bone. The disturbances inroot formation appeared in teeth which were trau-matized between Nolla’s developmental stages 2and 8.

Root dilaceration was present in 6 permanentincisors (4.7%)--5 incisors were successors of trau-

matized primary teeth and 1 incisor was in the non-trauma group (Table 2).

In some of the cases more than 1 type of changeoccurred in the same tooth. Two teeth presented withan arrest in root formation and demonstrated ex-tremely short, thinner than normal and grossly de-formed structure (patients 2 and 57).

Other pathological phenomena observed were:obliteration of pulp chamber (patient 39); severecrown and root malformation (odontoma-like for-mation in patient 57); tooth bud and bone sequestra-tion (patient 83); and transposition of a lateral incisorand the adjacent canine (patient 2). These cases werethe expression of extensive and severe traumaticevents to the primary dentition.

The small number of teeth with affected roots

did not allow statistical correlation between the con-sequences of the trauma and the type of trauma or

Nolla’s developmental stages. However, in the fol-lowing cases some of these relations are suggested.

Patient 57 demonstrated the effect of a severe

injury at a young age on the developing tooth buds.A 1-year-old girl fell off a staircase. The clinical ex-amination revealed luxation A[, intrusion of ~A, andlaceration of the gingivae around these teeth. No ad-ditional injuries could be observed on a periapicalradiograph.

Five months following the injury, a periapicalradiograph (Fig 1A) demonstrated that the primaryleft central incisor remained in an intruded positionand rotated with a resultant mesial and distal bonydefect. The right primary central and lateral incisorsshowed very wide pulp chambers, with an unex-plained "mineralized" area in the middle third of theroot of B_B_L. The permanent tooth bud of 1__L was atdevelopmental stage 3 and showed evidence of amineralization defect. The permanent tooth buds of~12 were poorly visualized and their location ap-peared to be more apical than their contralaterals.

290

TABLE 2. Distribution of Permanent Tooth Root Malformations According to the MostCommon Types of Trauma to the Primary Incisors

Type of Trauma

PermanentTeeth with

Permanent Other Root orTotal No. of Teeth with Surrounding Permanent

Primary Root Bone Malfor- Teeth withIncisors Dilaceration mations Normal Root

Luxation 26" 3 1 23Palatal displacement 22 1 -- 21Intrusion 9* 1 2 7Exfoliation 8 -- -- 8Others 10 -- 1 9Nontrauma 61 1 1 59

Total 136" 6 5 127

* In a few cases more than 1 type of root malformation occurred in a tooth.

ROOT DEVELOPMENT FOLLOWING TRAUMA: Zilberman et al.

FIG 1. Patient 57. A. Periapical radiograph taken 5 months after the trauma. Note the intruded and rotated ]A andthe poorly visualized 112 and their more apical location compared to their contralaterals. B. Radiograph taken 4years, 4 months following the injury. Note the mineralization defects of 111 and the severe crown and root mal-formation (odontoma-like formation) of J_2. C. Radiograph taken at age 12 years. Note the poorly developed root ofJ_l following apexification and root canal rilling.

Radiographs taken 4 years, 4 months followingthe injury revealed mineralization defects of 1|1,malposition of J_l and a severe crown and root mal-formation (odontoma-like formation) of J_2 (Fig IB).

|A previously had been extracted due to an infectedperiapical lesion. The right primary central incisorpresented with obliteration of the pulp chamber andpulp canal as well as premature resorption of the

FIG 2. Patient 83. A & B. Periapical radiographs taken at the first examination, 2 years following the injury. Note thepathological conditions of the primary teeth, especially on the right side. The crowns of 211 are underdeveloped andtheir follicles disturbed. C & D. Clinical photograph and periapical radiograph taken at age 9 years. Note the rudimentarycrown and irregular root formation of 2J_.

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FIG 3. Patient 39. A & B. Periapical radiographs taken 2 days after the trauma. Note the intruded BJ_ and thepathologic root resorption of A|A accompanied by periapical bone destruction. C. Periapical radiograph taken atage 10 years. Note the dilaceration at the middle one-third of the root of J_l and an obliteration of its pulp chamber.

apical third of its root. At this stage, A|B were ex-tracted and the severely malformed left permanentlateral incisor was removed surgically. At a furtherfollow-up examination, delayed eruption of J_l wasobserved.

At age 12 years, 11 years following the injury,the crowns of the maxillary central incisors pre-sented with severe hypoplasia accompanied by browndiscoloration. Additional white discoloration ap-peared on J_l. The left permanent canine erupted ad-jacent to J_l replacing the extracted J2. The periapicalradiograph taken at this stage (Fig 1C) showed J_lwith a poorly developed root. This tooth underwentan apexification followed by a conventional root ca-nal filling which had been performed 1 year earlier,due to periapical infection.

Patient 83 presented severe sequellae to an earlyintrusion of primary teeth. The child first presentedfor examination 2 years after having fallen on a hardobject at age 1 year. According to the informationobtained from his mother, 3 of his anterior teeth(CBA |) were intruded. Periapical radiographs takenat the time of examination demonstrated extensivepathologic root and bone resorption of A|, surround-ed by a periapical radiolucency, and pulp chamberobliteration of BAj (Figs 2A, B). The maxillary rightprimary canine presented with an obliterated pulpchamber and stunting of the root, as well as hypo-plastic defects on the incisal edge. Extensive cariouslesions were present in all anterior teeth. Underde-velopment of the crowns of 211 as well as distur-bances in their follicles also were evident. The budof 1_[ underwent sequestration and was removed sur-gically. Although the bud of 2_|_ presented signs ofdevelopmental disturbance of the crown, the deci-sion was made to retain it.

At age 9 years a rudimentary crown of 2_[ erupt-

ed into the oral cavity (Fig 2C). A periapical radio-graph revealed irregular root formation in additionto the deformed crown (Fig 2D). The patient wasreferred for combined orthodontic and restorativetreatment.

Patient 39 represents the nontrauma phenome-non, namely, damage to a permanent successor of aprimary tooth which was adjacent to a traumatizedprimary incisor. The patient was a 4V4-year-old girlwho presented to the Oral Surgery Department 2 daysafter having fallen at home. Clinical examination re-vealed intrusion of B_[ and soft tissue lacerations. Themaxillary primary central incisors had extensive car-ious lesions. Periapical radiographs taken at this time(Figs 3A, B) confirmed the clinical diagnosis andshowed pathologic root resorption of A|A accom-panied by periapical bone destruction. The maxillarypermanent central and lateral incisors appeared tobe normal and were at developmental stage 6. The 2primary central and the right lateral incisors thenwere extracted.

At age 10 years no enamel mineralization defectswere observed in the permanent central incisors.However, a periapical radiograph (Fig 3C) revealed,in addition to mesial caries of 1|, dilaceration of themiddle one-third of the root of J_l and an obliterationof its pulp chamber. Its periodontal ligament was alsowider when compared to its contralateral.

DiscussionThe influence of trauma to the primary incisors

on their permanent successors can be related to sev-eral factors such as the spatial relationship of theinvolved teeth, to the child's age at the time of in-jury, mainly to its dental developmental stage, andto the type of injury.56

In the present study the findings were similar to

292 ROOT DEVELOPMENT FOLLOWING TRAUMA: Zilberman et al.

those reported by Andreasen. *’6 The permanent in-cisors with affected root development comprised only4.7% of the examined permanent teeth. The widerange of developmental stages (2-8) of the tooth budsof the affected teeth suggests that the vulnerabilityof the developing root is not directly related to itsdevelopmental stage. The severity of root malfor-mation may, however, be related to the severity ofthe trauma. In the present sample the children withsevere disturbances in root development suffered anextremely traumatic injury.

The possible explanation to this assumptionmight be the different mode of transmission of thetraumatic force to the enamel organ and to the Herr-wig’s epithelial root sheath. The trauma to the pri-mary tooth is transmitted directly to the developingcrown of the permanent bud due to the close prox-imity of the primary tooth root and the developingenamel organ. 5,6 This hypothesis was confirmed in aprevious report in which most of the mineralizationdefects were found in the incisal one-third of thecrown, regardless of the developmental stage of thetooth bud.1 In contrast to that, the effect of trauma tothe Hertwig’s epithelial root sheath is the result ofthe transmission of the traumatic force through thesurrounding bone or through the primary tooth,causing deflection or displacement of the permanentbud. Such a course of events requires a traumaticforce of a considerable magnitude. This element andthe direction of the traumatic force are probably thecrucial factors in the observed root deformities ratherthan the developmental stage of the affected toothbud.

Another factor which could be of importance inthe transmission of the traumatic force might be thelength of the primary incisor root. In the investigat-ed sample, most of the primary incisors had fullyformed roots or were in the early stages of root re-sorption at the time of the injury. This did not allowevaluation of the effect of primary root length on the

development of the permanent tooth root. However,when this factor was studied previously in relationto mineralization defects on the permanent crownsno association could be established.2

The cases presented stress the need for close pe-riodic clinical and radiographic examination, sincesome of the pathological conditions developed a longtime after the trauma occurred. Parents should beinformed of this fact because lack of awareness leadsto noncompliance. These patients "disappear" andonly return when the clinical problem is already ful-ly evident.

This study was supported in part by a grant from the Joint Re-search Fund of the Hebrew University--Hadassah School of Den-

tal Medicine, founded by the Alpha Omega Fraternity and the

Hadassah Medical Organization.

Dr. Zilberman is a senior lecturer, Dr. Ben-Bassat and Dr. Brin arelecturers, orthodontics; Dr. Fuks is a senior lecturer, pedodontics;and Dr. Lustmann is a senior lecturer, oral and maxillofacial sur-gery, The Hebrew University. Reprint requests should be sent to:Dr. Yerucham Zilberman, Dept. of Orthodontics, The Hebrew Uni-versity, Hadassah Faculty of Dental Medicine, PO Box 1172, Je-rusalem, Israel.

1. Brin I, Ben-Bassat Y, Fuks A, Zilberman Y: Trauma to the pri-mary incisors and its effect on the permanent successors. Pe-diatr Dent 6:78-82, 1984.

2. Ben-Bassat Y, Brin I, Fuks A, Zilberman Y: Effects of trauma tothe primary incisors on permanent successors in different de-velopmental stages. Pediatr Dent 7:37-40, 1985.

3. Nolla CM: The deve.lopment of the permanent teeth. J DentChild 27:254-66, 1960.

4. Andreasen JO: Traumatic Injuries of the Teeth, 2nd ed. Copen-hagen; Munksgaard, 1981, ch 9.

5. Smith RJ, Rapp R: A cephalometric study of the developmentalrelationship between primary and permanent maxillary centralincisor teeth. J Dent Child 47:36-41, 1980.

6. Andreasen JO, Ravn JJ: The effect of traumatic injuries to pri-mary teeth on their permanent successors. II. A clinical andradiographic followLup study of 213 teeth. Scand J Dent Res 79:284-94, 1971.

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