|Year : 2010 | Volume
| Issue : 1 | Page : 40-48
Dowel-inlay a new treatment approach to traumatic root fracture
RG Sunil Reddy
Department of Conservative Dentistry and Endodontics, Rungta College of Dental Sciences and Research, Rungta Education Campus, Kohka Road, Kurud, Bhilai - 490 024 (C.G.), India
|Date of Web Publication||18-Nov-2011|
R G Sunil Reddy
Rukkus Residency, # 3-4-759, Opp: H.P. Petrol Pump, Barkatpura X' Roads', Hyderabad - 500 027, A.P
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Tooth trauma has been and continues to be a common occurrence that every dental professional must be prepared to assess and treat when necessary. Tooth trauma and its management loom as a major challenge to the dental practitioner. Transverse root fractures occur most commonly in the maxillary teeth. This case report describes a new technique for the management of transverse root fractures in zone 2 with dowel inlay. This enables the utilization of the fractured fragment crown for stabilizing a transverse root fracture in zone 2, in a simple, economical, and minimally invasive manner. It can save considerable time over other alternative treatment options available for the treatment of trauma zone 2 fractures. Both clinical and radiographic follow-up have shown a stable condition, without any probing defects, ongoing root resorption or periapical pathosis.
Keywords: Transverse root fracture, Zone 2 fracture, Post endodontic restorations, Cast Post, Dowel-inlay
|How to cite this article:|
Sunil Reddy R G. Dowel-inlay a new treatment approach to traumatic root fracture. J Int Clin Dent Res Organ 2010;2:40-8
| Introduction|| |
Root fractures of permanent teeth are a relatively rare form of injury, they account for approximately 6% of all dental trauma. Coronal one-third fractures account for 0.5 - 0.7% of all traumatic injuries of the teeth. ,
Transverse root fractures occur most commonly in the maxillary teeth, and are usually caused by an injury received in a fight or sporting event or by an inanimate object striking the teeth. , Transverse root fractures are fractures that involve the dentin, cementum, pulp, and periodontal ligament. Although not a common type of dental injury, they account for approximately 6% of all dental trauma, , and occur principally in adult patients, where the root is solidly supported in bone and periodontal membrane.  In younger patients the tooth is more likely to be avulsed. 
Important in the diagnosis of transverse root fractures is the fact that root fractures and luxations and fractures of the alveolar process appear exactly the same, clinically.  Differential diagnosis is therefore entirely dependent on a reliable radiographic technique, as is the later evaluation of the healing of these fractures. Based on the prognostic studies,  the general factors predicting the type of healing that occurs after transverse root fracture are similar to those associated with luxation injuries, and therefore it can be said that transverse root fractures are actually a luxation of the coronal segment only. 
The goal of restorative dentistry is to retain the natural teeth with maximal function and pleasing aesthetics.  It is generally agreed that the successful treatment of a badly broken tooth with pulpal disease depends not only on good endodontic therapy, but also on good prosthetic reconstruction of the tooth after the endodontic therapy is complete.  The primary purpose of a post is to retain a core in a tooth that has lost its coronal structure extensively.
During the treatment procedure, a structurally compromised tooth can give rise to complications such as root fracture, loss of restorative seal, dislodgement of the core, and periodontal injury, due to biological width invasion during margin preparation.  There are many techniques of restoring a transverse root fractured incisor tooth after successful endodontic treatment, which should be complemented by sound coronal restoration. This should ideally meet the requirements of the function and aesthetics. It is easier to make cast metal restorations with the aid of dowel / post, dowel-Inlay for retention and lasting service.
A dowel-inlay is a combination of dowel and inlay, wherein, the inlay is locked to the dowel, which helps in improving the retention of the restoration, as well as resistance to laterally directed forces. 
If a dowel with an attached inlay is utilized, the inlay is locked to the dowel, and some retention is imparted to the restoration, as also resistance to the laterally directed forces. As this restoration is a combination of a dowel and an inlay, the consistent nomenclature would suggest the use of a dowel-inlay to describe it. 
| Case Report|| |
A 55-year-old male patient presented to the Department of Conservative Dentistry and Endodontics, College of Dental Sciences, Davangere, Karnataka with a primary complaint of mobility of the maxillary left central incisor and a history of biting on a hard nut two days back. On examination it an unrestored maxillary left central incisor was found,  exhibiting Grade II mobility [Figure 1].
However, tooth 21 was asymptomatic and the clinical crown was intact. The fracture was not evident labially and the adjacent teeth showed incisal wear, faceting, and chipping. Occlusal wear was also noted on the posterior segments. Periodontal probing indicated apparent periodontal pockets and further periodontal assessment showed the coronal tooth fragment to be still attached through a fragile soft tissue junction around the labial aspect. The crown remained in its anatomical position with regard to aesthetics and the occlusion. A radiographic examination of the tooth revealed a clear radiolucent line 3 mm below the alveolar bone crest, suggestive of transverse root fracture zone 2. , No periapical changes were noted in relation to the tooth [Figure 2].
A diagnosis of chronic generalized periodontitis associated with transverse root fracture zone 2 was made [Figure 3] and root canal treatment was performed [Figure 4].
A Gates Glidden drill No. 2 (DENTSPLY Maillefer, Ballaigues, Switzerland) was used to remove the gutta percha post space was prepared with a peeso reamer in relation to tooth No. 21 [Figure 5]. Care was taken to ensure that the length of the post was two-third the length of the canal; half the bone supported the length of the root or in other words, the length of the clinical crown. 
An H file was used circumferentially to smoothen the preparation of the post space. The mouth of the canal should be extended enough to remove any under cuts particularly toward the facial wall of the preparation. Smooth internal walls were also important for the fit of the inlay component of the restoration. The widening of the orifice of the canal was done with a round end tapered diamond. The incisal 2 - 3 mm of orifices was flared to form the inlay portion of the preparation. A No. 170 bur was used to smoothen the walls. To achieve the best possible marginal adaptation of the final restoration, a well-defined, wide bevel (1.0 mm or greater) was given around the entire surface of the mouth of the canal. 
The gingival portion of the bevel was at approximately a 90 angle to the path of insertion of the dowel. , Finishing touches were added to the bevel with a white polishing stone. As the lingual surface of the crown closely approximated the path of insertion of the dowel the finish for the incisal segment of the bevel might not be as well-defined. 
The direct wax pattern technique was the only sensible choice for the indirect fabrication of a dowel-inlay in this transverse root fractured central incisor.
Orange wood stick (Post) was selected and trimmed and shaped conically to passively fit, to full length, the prepared post space of the root canal. The orange wood stick was coated with type I inlay Patten wax and placed in the prepared post space in the canal. The wax pattern had one dowel attached with a concave lingual surface of the inlay component.
After casting, the sprue was removed with a carborundum separating disk. The excess contour, where the sprue was attached, was trimmed, producing a slight concavity in the lingual surface of the inlay , [Figure 6]. There had to be a V-shaped cement escape vent on the side of the dowel, but it had to end about 2.0 mm from the inlay margin, to avoid the possibility of a marginal defect. ,
|Figure 6: The dowel-inlay is ready for cementation with slight concavity in the lingual surface of the inlay|
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As seen before cementation the dowel-inlay had a concave lingual surface in the inlay component [Figure 6].
Type I Glass Ionomer Luting cement (Fuji I) was used for the final cementation of the dowel-inlay.
The cement was applied to the dowel preparation with a periodontal probe or Lentulo spiral cement filler. Care was taken to coat the walls of the canal all the way to the apical end of the dowel preparation. ,
The dowel-inlay was inserted into the cement-filled orifice of the canal, pushing it in with finger pressure. A condenser was used to seat the dowel-inlay completely in place.  The margins were checked with an explorer. Pressure was maintained on the dowel-inlay, with the instrument, until the cement set.
The dowel-inlay was cemented in the canal, providing a closure of the endodontic access, with reinforcement of the root and coronal tooth structure under the crown.
A carborundum stone was used to adjust the contour of the dowel-inlay to blend in with that of the adjacent lingual surface. Initial steps could be taken for margin finishing, always orienting the stone so that it revolved from the inlay to the surrounding crown. The margin finishing was completed by using a white polishing stone and petrolatum, and moving the stone from inlay to crown. A large, coarse, red rubber point was used to smoothen the surface of the inlay, to eliminate the scratches produced by abrasive stones. A final polish was added by using a large, fine, green rubber point. The completed dowel-inlay was seen cemented to the natural crown [Figure 7] and [Figure 8].
|Figure 7: The completed dowel-inlay is seen cemented to the natural crown|
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|Figure 8: Postoperative view in labial aspect with soft tissue integrity|
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The completed dowel-inlay was cemented in the endodontic access opening, into the lingual surface of the transverse root fractured (zone 2) central incisor's anatomical crown.
The occlusion was then checked on a follow-up examination after 15 days [Figure 9],[Figure 10],[Figure 11], one month, two months, and six months [Figure 12]. Satisfactory healing was evident both clinically and radiographically.
| Discussion|| |
Usually the presence of a transverse root fracture is clearly evident on radiographic examination;  although the fracture line can be missed, if radiography is performed immediately after the injury, because at that stage the fracture line may be barely discernible. Just as research has demonstrated the need for multiple radiographic exposures in the diagnosis of dental trauma, the same is true for the disclosure of transverse root fractures. ,,
The angulations of the vertical beam are important because they can alter the fracture line, causing the fracture to disappear completely and making differentiation of the hard and soft tissue extremely difficult.  To accurately diagnosis a transverse root fracture, a steep occlusal exposure, as well as two conventional periapical bisecting-angle exposures are recommended. ,
In some zone 2 fractures, the base of the gingival crevice is very close to the transverse root fracture. It merely takes some mild inflammation to start an apical migration of the base of the gingival crevice. Eventually, communication with the fracture line is a certainty. Once this communication exists, the coronal segment may be lost [Figure 3].
An occlusal radiographic view is ideal for disclosing fractures in the apical one-third of the root; periapical radiographic views are better for visualizing coronally located root fractures. , The direction of the fracture line changes from an oblique angle in the apical and middle third of the root to a more horizontal fracture line in the cervical one-third. Thus, an occlusal view shows apical and middle third fractures, while a periapical view shows the more coronal fractures. Failure to expose both of these radiographs could easily result in misdiagnosis. 
The most common clinical finding is that the tooth is slightly extruded with a lingually displaced crown - and the coronal segment is laterally luxated. When a tooth suffers an impact that fractures the root of the tooth, a single tooth becomes two teeth. As long as it is undisturbed, the apical segment remains vital in 99% of the cases and usually is not a problem.  The coronal segment may or may not be vital and may or may not be mobile, depending on the state of the tooth at the time of fracture, the extent of the fracture, and the location of the fracture line.
A transverse root fracture can be classified into three zones , [Figure 13]
|Figure 13: Classifi cation of Transverse root fracture (Courtesy Dr. Barry Feiglin)|
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Zone: 1 Extends from the incisal edge to the alveolar bone crest
Zone: 2 Ranges from the alveolar bone crest to 5 mm below
Zone: 3 Extends from 5 mm below the alveolar bone crest to the apex of the root
| The Nature of the Fracture Line|| |
Correct management of the tooth with a transverse root fracture depends on the complete understanding of what is occurring between the segments of the fractured tooth. Transverse root fracture healing can involve union of segments with hard tissue, interposition of connective tissue (periodontal ligament), or nonunion with associated interposition of the granulation tissue. According to the experimental ,,,,, data and literature on this subject, a true union across the fracture line is a relatively uncommon occurrence; the 'healing' that apparently occurs is the result of consolidation of the surrounding and supporting tissues. 
Andreasen and Hjorting-Hansen  were the first to describe the four categories into which the transversely root fractured tooth may be classified. The coronal and apical segments may have union by hard tissue, union by fibrous tissue, union by bony in-growth across the fracture line or in-growth of chronic granulation tissue.
Union of the coronal and apical segments by hard tissue is the most desirable outcome, but occurs relatively infrequently. The coronal and apical segments of the fractured tooth are brought together and remain without mobility. The chances of healing by hard tissue across the fractured segments is normally increased only if a small amount of luxation of the coronal segment occurs (concussion is far better than extrusion), if the segments have only a small amount of separation, if the 'fracture foramen' of the coronal segment is large, or if the patient is young rather than elderly.
Timing is significant for hard tissue union across the fracture line.  When a tooth is splinted immediately after trauma, a greater chance exists of hard tissue union, than if the tooth is treated the next day when the granulation tissue is already in place. If hard tissue union occurs, the root may show a stage of 'tunneling resorption,' which does not affect the prognosis of the tooth, but can appear quite dramatic on a radiograph.
Hard-tissue union does not occur in teeth with restorations or marginal periodontal disease. 
Union of the coronal and apical segments by way of fibrous tissue is the more common event after transverse root fracture and occurs where slight mobility exists during the healing process. Union of the coronal and apical segments by bony in-growth across the fracture line occurs principally during growth spurts of the child. The coronal segment of the fractured tooth moves with the growing bone and leaves a bony interface between the two fractured segments,  which heals by interposition of bone and connective tissue (due to a growth component).  Therefore, these latter two categories are the same. The chance of healing with connective tissue is significantly increased by  the increased age of the patient at the time of fracture,  the presence of restoration in the tooth, and  orthodontic band splinting of the tooth.
Attempted union of the coronal and apical segments by in-growth of granulation tissue occurs if infection exists in one of the segments (usually the coronal segments). Granulation tissue also forms if the fracture line communicates with the oral cavity.  Interposition of the granulation tissue between the two fractured segments is caused by increased luxation of the two segments (extrusion is greater than concussion), increased loosening of the coronal segment, decreased diameter of the 'fracture foramen' in the coronal segment, administration of antibiotics at the time of injury, and orthodontic band splinting. No teeth with interposition of granulation tissue have wide open apices. 
From the management point of view, the transversely fractured tooth segments can be considered as separate entities in virtually all cases. On a practical level, all treatment regimens are directed at management of the coronal segment only. ,,,,
Radiographic and histological observations in humans have shown that the healing events after root fracture can be divided into four types: 
- Healing with calcified tissue
- Interposition of connective tissue
- Interposition of bone and connective tissue
- Interposition of granulation tissue
Traumatic injuries involving tooth root fracture can now be treated by dowel-inlay, to provide what is considered to be the most conservative of restorations.
Factors influencing the extent and feasibility of such repairs include: ,,,,
- Position of the tooth after it has been fractured
- Mobility of the coronal segment
- Status of the pulp
- Position of the fracture line
- Status of the periodontium
- Time and resources of the patient
The general approach to management of transverse root fractures is summarized in [Table 1].
The dowel-inlay technique was first introduced by Shillingburg, in 1982.
If the tooth is endodontically involved, a cast dowel core that passes through the crown and into the root can solve the retention problem and obviate the prefabrication of the crown. This is the same technique that Shillingburg describes as the dowel-inlay crown repair. , This technique is used in cases without crown loss, to restore the endodontic access opening, and at the same time strengthening the tooth. This technique for stabilizing a crown with a post and core that pass through the crown is quite simple, and can save considerable time and expense. Also this technique utilizes the standard materials and method used to produce dowel-inlay castings.
A.F. Mc Mullen et al., suggest that if endodontic therapy must be done on a tooth after it has received a crown, the access opening will diminish crown retention by 61%. [Ή 9] They have described the placement of dowel-inlay for stabilizing the crown.  David E. Snyder, has suggested the use of dowel-inlay for repair of the loose crown of an endodontically involved tooth.  dowel-inlay can also be used for stabilizing crowns that are over tapered or short crown preparations. ,,
Other treatment options available in the treatment of transverse root fractures in zone 2 include: ,,,,
- Periodontal adjustment
- Orthodontic extrusion
- Intra-alveolar transplantation of the fractured tooth
- Root extraction and prosthetic replacement
- Root burial and prosthetic replacement
- Surgical extrusion involving extraction and reimplantation and restoration
However, many of the above-mentioned techniques have limitations. These may not be as cost-effective and may be less conservative in nature.
| Conclusion|| |
In general, if the tooth can be repositioned, stabilized, and occlusally adjusted, the prognosis of a transversely root-fractured tooth is quite favorable. However, if the fracture occurs in zone 2, a complicated and extended treatment regimen may be necessary and sometimes the prognosis may be poor.
No two dental fractures are similar, so we should avoid the use of a cook-book method. Each one has to be treated as a separate new case; each injury projects its own pattern and has to be treated differently [Figure 4]. The clinician must judge every situation on its individual merits and select a procedure that fulfills the needs of the case, while maximizing stability and minimizing mobility.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13]