Evaluation of the Accuracy of Cone Beam Computed Tomography for Immediate Implant Placement- A Case Report.

Diagnostic imaging acts as a distinctive method in analyzing and drawing in the appropriate treatment protocol for any procedure. Pertaining to immediate implant placement, determining the bone width and height plays a vital role in the success of the implant therapy. This visualization of the measurements done preoperatively will enhance the treatment by reducing the overall time span of the procedure. Currently, cone beam computed tomography (CBCT) plays a significant role in the preoperative determination of the measurements of the tooth and the bone. This case report is regarding, a 27-year-old male patient reporting to the Department of Oral and Maxillofacial Surgery at Madha Dental College and Hospital, with a chief complaint of fractured crown in relation to the upper left front tooth region. On clinical examination, there was the presence of an endodontically failed and fractured crown in relation to 22. With the interpretation of clinical and radiographic examination, the tooth was categorized under unfavorable prognosis. The patient was given a detailed description of the various treatment procedures available pertaining to that present condition, along with immediate implant placement procedure. Since the patient was young and conscious about his esthetics and accuracy, he opted for placement of immediate implant followed by extraction of the tooth. To accurately determine the length and width, the tooth and socket measurements were preoperatively measured by CBCT. This article evaluates the accuracy of CBCT by comparing the clinical quantity of bone and dimensions of tooth to be extracted and alveolar socket.

INTRODUCTION

According to Branemark, a period of 12 months after tooth extraction is recommended before the placement of the implant. In addition, a subsequent healing period of 3–6 months is indicated after implant fixture placement. In most instances, this translates to 1–2 years from the start of treatment to completion of the restoration.[1] This often leaves the patient with the missing tooth or teeth with an extended period. Thus to shorten the overall length of treatment the implant could be immediately placed after extraction of the natural tooth.[1]

By doing so, less surgical interventions, better esthetics with good implant survival rates, improved preservation of the hard and soft tissues at the extraction region, and tremendous patient satisfaction compared with delayed (late) implant placement can be achieved.

Alveolar ridge resorption after tooth extraction may considerably reduce the residual bone volume and compromise the favorable positioning of implants required for optimal restoration.[2] This is even more pronounced at the anterior maxilla, where ridge resorption often creates an unfavorable palate-labial discrepancy between the implant and the prosthesis. Following the correct clinical indications, the immediate placement of the implant into the extraction socket avoids this undesirable resorption.[3] Frequently, however, compromised teeth that are indicated for extraction are involved with infectious conditions, which conventionally contraindicate their immediate replacement with endosseous dental implants.[3]

However, the success of the implant lies primarily with the amount of alveolar bone. Hence, it is important to evaluate the socket preoperatively. Although intraoral periapical radiograph (IOPA) and orthopantomogram (OPG) can aid in determining the socket dimension, they are confined to a 2-dimensional view. To overcome this drawback CBCT was introduced which enables the doctor to view the area of interest in a 3-dimensional manner, ultimately resulting in more precision diagnosis preoperatively.[4]

CBCT is a medical image acquisition technique that is comprised of X-ray computed tomography in which the X-rays are divergent, forming a cone. Since then there has been a great interest in this new imaging technique in the oral and maxillofacial surgery region by different research groups, the CBCT has proved to be an efficient preoperative diagnostic tool in the measurement of the width of the alveolar bone, width and length of the tooth.

The present study was a case report evaluating the accuracy of CBCT for immediate implant placement for a young patient in endodontically failed maxillary front teeth.

MATERIALS AND EQUIPMENT/ARMAMENTARIUM

Root form endosteal threaded implant, selective integrated surface (sandblasted and acid etched surfaced) were used

Surgical Armamentarium for atraumatic tooth extraction and immediate implant placement.

Surgical guide drill: Conventional (No. 4 or No. 5) round bur was used to initiate the bone drilling [Figure 1]

Figure 1

Implant kit

Surgical twisted drills: Surgical twist drills of various diameters ranging 2.0 mm to 4.2 mm were used in sequence to prepare the site [Figure 1]

Depth gauge/paralleling pin: These gauges were used to obtain parallel preparation and to guide the direction of drilling preparation. Depth gauge also aids in determining the depth of the surgical preparation for implant placement

Physiodispenser and reduction hand piece with internal irrigation: Used for bone drilling [Figure 2]

Figure 2

Physiodispenser

Hex ratchet: Hex ratchet was used to engage the fixture insertion tools to screw the implant in its proper position

Standard diagnostic Tools [Figure 3]

Figure 3

Surgical instruments

Extraction and socket expansion instruments [Figure 4].

Figure 4

Bone expanders

To prevent infection, all surgical procedures were performed under strict aseptic conditions with the greatest attention paid for the preservation of implant bed. A routine medical history, intra- and extra-oral clinical examination and complete blood investigations were performed. A thorough assessment of the future implant site was carried out. The available vertical, mesiodistal and labiolingual, tooth and socket dimensions was evaluated by CBCT.

Diagnostic aids

Preoperative intraoral IOPA [Figure 5], OPG [Figure 6], and study models [Figures 7 and 8] were taken.

Figure 5

Preoperative intraoral periapical radiograph

Figure 6

Preoperative orthopantomogram

Figure 7

Study model - Labial view

Figure 8

Study model - Occlusal View

Surgical technique

Pre-operative Extra oral photograph was taken [Figure 9].

Figure 9

Extraoral profile of the patient

Pre-operative intra oral view [Figure 10] reveals the presence of endodontically failed left lateral incisor tooth with fractured crown.

Figure 10

Preoperative intraoral view reveals the presence of endodontically failed left lateral incisor tooth with fractured crown

A pre-operative cone beam computed tomography is taken, width of buccal and palatal bone, approximate width and length of tooth is measured [Figures 11-14.

Figure 11

A preoperative cone beam computed tomography to determine the width of buccal bone

Figure 14

Measurement of length of 22 using cone beam computed tomography

The implant dimensions is selected such that it is 1-1.5mm larger than the tooth to be replaced.

Local anaesthesia was achieved using 2% lignocaine with 1:80,000 adrenaline.

After adequate periosteal reflection atraumatic extraction of the tooth is done using periotome [Figure 15] and extraction forceps without damaging the buccal and palatal shelf.

Figure 15

Atraumatic removal of the tooth using periotome

Clinically the dimensions of the tooth are measured [Figure 16].

Figure 16

Measuring the extracted tooth clinically

The preparation of the extraction socket was done with osteotomes (bone expanders) [Figure 17].

Figure 17

Expansion of socket using osteotome (bone expander)

Implant is placed in such a way that the implant touches all the bony walls of the extraction socket [Figure 18].

Figure 18

Placement of the implant in such a way that it touches all the bony walls of the extraction socket

Healing cap is placed [Figure 19].

Figure 19

Placement of healing cap

The surgical site is sutured with 3 -0 braided black silk suture [Figure 20].

Figure 20

Suturing done using 3-0 silk suture

A preoperative cone beam computed tomography to determine the width of palatal bone

Measurement of width of 22 using cone beam computed tomography

RESULTS

A young patient with an endodontically failed fractured crown was treated using an implant placed into the freshly extracted socket using flapless approach. The implant was placed immediately after extraction using preoperative cone beam computed tomography (CBCT) measurements of the tooth and the socket in the maxilla.

The diameter of the implant ranged from 3.5 to 5 mm. The implant length ranged from 11.5 to 16 mm. The dimension of the implant was selected based on CBCT.

The length and width of the tooth was measured both clinically and in CBCT [Table 1], and a comparison was made to assess the accuracy of CBCT. Similarly, the labial and palatal bone thickness in relation to the teeth was measured both clinically and in CBCT [Table 2], and a comparison was made to assess the accuracy of CBCT.

Table 1

Tooth dimensions

Table 2

Bone thickness

DISCUSSION

The most currently used treatment option for management of complete or partial tooth loss is dental implants. An obvious area of interest lies in the reduction of the treatment span to complete the implant therapy and to improve esthetics.[5]

The placement of immediate implant after extraction of a natural tooth helps to achieve this goal. Immediate implant and early loading is considered as the latest treatment plan with good results for replacement of anterior teeth with success rate of 66%–95.5% in maxilla and 90%–100% in mandible. Immediate implant placement is most commonly indicated when tooth extraction is due to trauma, endodontic lesion, failure of root canal therapy, root fracture, resorption of root, endodontic mishaps such as root perforation, unpropitious ratio between the crown and root (not due to periodontal loss), and presence of intact bony walls in the alveolus. Contraindications include the presence of infection, inadequate bone (<3 mm) beyond the tooth socket apex for initial implant stability and gingival recession. In the recent times, success rates of about 95% or more have been reported, but this has been attributed to the evolution in the imaging technology which is required during all the phases of the implant placement therapy.

A preoperative dental implant treatment planning is essential to provide accurate and specific data pertaining to the implant site. The conventional preimplant imaging modalities such as IOPA, OPG, RVG, cephalometric, and tomographic images are 2-Dimensional images where accurate measurements of the bone width and height, tooth dimensions are not possible. These also possess disadvantages such as superimpositions, projection geometry, and completely lack the third dimension of bone depth. Hence, 2-Dimensional image as a diagnostic tool is not 100% accurate and reliable.[6]

Later when computed tomography (CT) was invented, it became the gold standard in implant dentistry as it is a 3-Dimensional imaging modality which helps the clinicians to view the region of interest and the appropriate skeletal anatomy in relation to maxillary sinus and mandibular nerve.[6] Medical CT has the following advantages such as uniform magnification, multi planar views, and simultaneous study of multiple sites in a 3-dimensional perspective. However, the major disadvantage of medical CT is the one large effective radiation dose, the scanning of one jaw can be equivalent to 10 panoramic X-rays.[6] Furthermore, the radiation exposure of CT is 3–10 times higher than that of CBCT.[7] Other disadvantages would be its high cost, improper imaging of the inferior alveolar nerve canal, and it suffers from beam hardening artefact or scatter due to adjacent metal structures such as restorations.[8]

As an alternative measure for 3-dimensional imaging modality, in the recent 2001, CBCT was developed with many advantages. The major built-in error in medical CT scanners is the development of gaps between the slices which is avoided in CBCT as there is minimal or no development of gap because the X-ray volume minimally contact each other.[8] Avoidance of gap is made possible in CBCT since the volumes of data are obtained in a single 360° rotation around the patient's head.[6] CBCT also captures objects with high contrast and possess excellent image acquisition of various structures such as inferior alveolar nerve canal, thereby it is considered more superior than medical CT.[9] In addition, the radiation exposure of CBCT is comparatively less than medical CT. For medical CT, a patient gets exposed to an equivalent of 38 days of background radiation whereas for CBCT only 6–12 days of background radiation.[9]

Thus, the ideal imaging modality for the preoperative radiographic assessment of potential implant sites should produce the desired diagnostic information to the operator while minimizing the cost and risk to the patient. Numerous studies have suggested that CBCT is the recent trending advancement in the imaging modality and also the best alternative to CT for preoperative evaluation of the dental implant site.[6]

Hence, in our case report, in addition to IOPA, OPG we have opted for preoperative cone beam CT as a diagnostic aid. CBCT was chosen as an effective imaging modality, because of its minimal radiation exposure and better imaging reconstruction of the measurements than conventional CT. With the help of CBCT, we have measured the preoperative buccal bone width and height, palatal bone width and height and tooth measurements, preservation of the buccal bone and the palatal bone was made possible by performing an atraumatic removal of the tooth using periotomes.[10] The tooth width and height measured clinically were compared with CBCT measurements which revealed that CBCT measurements were 98% accurate in terms of the width of the teeth and 99.06% accurate in terms of the length of the tooth.

The buccal bone width is measured clinically, and it is 1 mm while that measured using CBCT is 0.9 mm. The accuracy of cone beam CT over clinical measurement was 88.98%. The palatal bone width is measured clinically which is 1.5 mm while that measured using CBCT was 1.6 mm. The percentage of accuracy of CBCT over clinical measurement is 97.14%. According to these measurements, appropriate implant dimension was selected.

Since the buccal bone width is less the implant was oriented toward the palatal side, and it was submerged below the bone level as marginal bone loss is more common in anterior region. Following the implant placement, primary stability was checked clinically. An IOPA was taken postoperatively to check for the position, and it was satisfactory.

While implant placement in the extraction socket is desirable for a number of reasons previously described, there are number of challenges such as unfavorable extraction socket morphology, which is avoided in our study because we have used preoperative CBCT where we measured the socket, inadequate soft tissue for implant coverage, and bone defects that may present unique challenge to the clinician in the quest for implant placement.[6]

CONCLUSION

The CBCT measurements of the tooth and alveolar socket are more accurate in immediate implant treatment. The implants placed into the sockets will heal predictably and therefore cause reductions in the number of surgical interventions and in the total span of treatment time.

In this case report, usage of CBCT as a preimplant imaging technique has proved that evaluation of the measurements are more accurate than clinical measurements with a percentage of 98% in relation to the width of the tooth, 99.06% in relation to the length of the tooth, 88.98% in relation to the labial bone thickness, and 97.14% for palatal bone thickness.

Since the clinical outcome of immediately placed implants is successful and survival rate is high, hence this case report, CBCT-assisted immediate implant placement can also be included in the modality of treatment of vertical or horizontal fractured or resorbed, or failed endodontic teeth in anterior maxilla.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.