Introduction

The provision of dental implants has widely been considered as one of the viable options available for definitive replacement of teeth in cases following traumatic dental injuries. Despite this, there can be many challenges entailed, especially in the anterior maxilla as a result of the higher aesthetic demands. Although there are clear guidelines for the management of traumatised teeth,1 the extent of these injuries can render them with a guarded prognosis, with intrusions and avulsions having been reported to be at higher risk for ankylosis and resorption.2,3,4

Traumatic injuries that occur in childhood and adolescence precludes the placement of dental implants due to the continuous growth of the facial structure and risk of infraocclusion.5,6,7 Therefore, it can be advocated to maintain these teeth for as long as possible, although irreversible signs of pathology may necessitate the need for removal. Following dental extractions, the labial wall undergoes the highest degree of resorption, which has been attributed to the consistency of bundle bone supplied by blood from the periodontal ligament.8,9 The nature of the impact itself can cause additional trauma to the alveolar bone and soft tissues, resulting in horizontal and vertical bone atrophy. Subsequently, before implant placement, bone and soft tissue augmentation may be indicated to compensate for the marked resorption and scar tissue that can develop following traumatic dental injuries.10,11,12

Immediate implant placement into fresh extraction sites can provide numerous advantages, primarily including fewer surgical interventions, a reduction in overall treatment time and enhanced soft tissue maintanance.13,14 Although in theory immediate placement could prevent hard tissue resorption of the buccal plate that can follow dental extraction, studies have demonstrated that the morphologic changes of the alveolar ridge can still occur despite these placement protocols.15,16 Previous systematic reviews comparing outcomes of implants placed into fresh extraction sockets versus delayed placement into healed bone have suggested that although the aesthetic outcome can be beneficial, immediate implants can have a higher overall failure rate.17 As a result, the timing of implant placement continues to be an important area of debate within the literature. Although favourable outcomes have been reported with the use of immediate implants in fresh extraction sites, the use of immediate implants in cases following severe dental trauma have not been as widely documented or reported.18

The aim of this study was to evaluate the implant and prosthetic survival rate for implants placed in the anterior maxilla immediately after tooth extraction following a traumatic dental injury with assessment of periodontal outcomes at a three-year follow-up period.

Materials and methods

Study population

This retrospective study was conducted using data from patients seen for the management of traumatic dental injuries in the anterior maxilla. The inclusion criteria were at least 19 years of age at the time of implant placement; systemically healthy; good oral health with no periodontal disease; and had immediate implant placement in the anterior maxilla from the incisor to canine region at a site following trauma. All of the patients received the implant within two months of their traumatic dental injury.

The exclusion criteria included: smokers; pregnancy; parafunctional habits; and any conditions that would compromise healing, such as those treated with intravenous bisphosphonates. Any patients presenting with dental trauma with active primary dental disease were not considered for implant treatment. Periapical lesions did not automatically exclude patients but they were informed that if the amount and extent of bone loss would hinder placing an implant and achieving primary stability, they would not receive the planned treatment and this would be deferred for delayed implant placement.

Surgical protocol

All of the cases were treated by a single operator who performed the extraction and implant placement, prosthodontic management and reviews for all the patients. The procedures were performed under local anaesthesia for all acute traumatic cases as well as historical trauma cases (Fig. 1). The sites were assessed and deemed suitable for an immediate implant following a clinical assessment and review of a periapical radiograph. Consent was obtained to include failure to achieve primary stability as well as osseointegration. Antimicrobial prophylaxis was administered to each patient before the procedure as a single oral dose of 3 g amoxicillin, or 600 mg clindamycin if they were allergic to penicillin, followed by rinsing with chlorhexidine gluconate mouthwash for one minute. After local anaesthesia infiltration with articaine, the patients were prepped using a surgical gown. The tooth to be extracted was removed atraumatically using luxators to maintain an intact buccal plate (Fig. 2). The socket was irrigated with saline and then inspected for any granulation tissue that was curetted out. Once clean, the socket was confirmed as being suitable for achieving primary stability with adequate apical bone present (Fig. 3).

Fig. 1
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Traumatic dental injury resulting in a non-vital, discoloured upper left lateral incisor

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Fig. 2
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Extraction of the upper left lateral incisor showing signs of external resorption

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Fig. 3
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Atraumatic extraction maintaining the labial plate and supporting soft tissues

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The osteotomy preparation was initiated using a rose head bur to create an application point, 3 mm from the apex of the socket and angled palatally engaging the palatal shelf (Fig. 4). The 2.2 mm twist drill was then used at 27,000 rpm (according to the manufacturers guidance) to prepare the bone to the pre-determined length and the depth and angulation were checked with a direction indicator. When satisfied with these indicators, the 3.0 mm and 3.4 mm twist drills were then used to enlarge the osteotomy site to the chosen implant length. Finally, any sharp palatal bone was reduced using a countersink preferentially on the palatal aspect.

Fig. 4
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Implant placement at the palatal aspect to facilitate a screw-retained restoration

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All of the implants were Neoss (Neoss Ltd, Harrogate, UK) with the appropriate length and diameter selected before the procedure. The implants used had a low surface roughness and super hydrophilic surface. All of the implants were placed without any bone grafting or augmentation. Leaving some blood in the socket, the implants were then placed at 40 Ncm (in line with the manufacturers guidance) and unless there was an anticipated soft tissue deficiency when a cover screw was used, healing abutments were screwed onto the implants and the immediate denture adjusted to fit without undue pressure on the implants (Fig. 5). This was the standard protocol used. A periapical radiograph was taken to confirm the position of the implant placed relative to adjacent teeth (Fig. 6).

Fig. 5
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Placement of healing abutment without bone augmentation between the socket wall

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Fig. 6
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Implant submerged for four months with the placement of a provisional restoration

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Prosthodontic protocol

The immediate implants were left to heal for four months, after which the healing abutment was removed and the stability of the implant checked with a sharp probe and digital pressure. This was performed without local anaesthesia if the patient had successfully kept the gingival tissues clean and healthy. If there was gingival overgrowth covering the healing abutment, this was removed under local anaesthesia prior to taking the working impression.

A polyether impression was taken using a stock tray with a hole over the implant position and an impression coping attached to the implant. After taking a shade, a request for a screw-retained implant crown for retrievability was made, which was fitted four weeks later under local anaesthesia (Fig. 7). The fit was subsequently checked by taking a post-operative periapical radiograph (Fig. 8). When all parameters, including the fit, shape, colour and occlusion, were satisfactory, the crown was secured with a gold screw at 32 Ncm. The screw access hole was then filled with polytetrafluoroethylene tape and composite and the occlusion was checked again to ensure that there was no premature contact.

Fig. 7
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Final implant retained definitive crown replacing the upper left lateral incisor

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Fig. 8
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Post-operative radiograph to confirm implant placement position and fit

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The patients were given oral hygiene instructions with specific use of superfloss around the implant crown. At the initial follow-up visit three months later, the level of oral hygiene, gingival probing depths, bleeding on probing were noted as well as the implant stability and function. The occlusion was checked again and if satisfactory, the patient was given a second review appointment six months later. At the next review appointment, in addition to further clinical examination, a periapical radiograph was taken to check the extent of the bone healing. The patients were then placed on yearly review with both clinical and radiographic assessments of the implants and the restorations for a follow-up period of three years.

Outcome measurements

Implant success was initially defined as the presence of a functional implant in the absence of clinical signs of pain, infection and mobility, with no radiographic features of failed osseointegration.19 Implants that had to be removed due to mobility or with radiographic evidence of peri-implant pathology, were considered as failures.

Prosthodontic evaluation was recorded from initial placement at the second stage surgery to the end of the follow-up period of three years by the same operator. The definitive prosthetic suprastructure was considered successful if it was in continuous function and stable upon clinical examination at the review stage.

The periodontal health clinical parameters recorded were bleeding on probing and gingival probing depths. These assessments were performed at six sites for each implant and the presence of any biological or technical complications were also noted.

All of the periapical radiographs were taken with standard Rinn attachments and were not standardised for each patient. As a result, this study is unable to calculate to any degree of accuracy any marginal bone loss.

Statistical analysis

The statistical analysis was performed using SPSS Statistics (IBM Corporation, New York, USA). Descriptive analyses to present quantitative data included calculating the means, standard deviations and ranges for the outcome variables, including implant and prosthetic survival.

Results

Demographic data

In total, 60 patients (37 men, 23 women), ranging in age from 21-61 years with a mean of 34.5 years, were included, who had received immediate implants in the anterior maxilla following dental trauma. The patients were clinically followed-up for three years.

A total of 70 Neoss implants were placed (Neoss Ltd, Harrogate, UK), all of which were 4 mm in diameter in the anterior maxilla. Most of the patients had single tooth replacement with a screw-retained crown and five patients with implant screw-retained bridges. The most frequent teeth being replaced with an immediate implant were central incisors as shown in Table 1.

Table 1 Implant position and length parameters (n = 70)
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In relation to the implant length, the majority were 13 mm and 15 mm as reported in Table 1 and the reasons for replacing the traumatised tooth with an immediate implant are shown in Table 2. Teeth with a poor prognosis were predominantly crown-root fractures and those with historical trauma and extensive root resorption as a sequelae.

Table 2 Indications for extraction (n = 70)
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Surgical outcomes

Of the 70 implants placed, three failed resulting in an implant survival rate of 95.7% over the evaluation period. All the failed implants were in the central incisor region and failures occurred within the first year of placement (4-9 months). The distribution of failed implants together with the mode of failure are listed in Table 3.

Table 3 Biological/technical complications observed
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For the implants that survived, there was no evidence of pain or infection recorded and no mobility or signs of peri-implant radiolucencies were noted at the follow-up appointments. For those that had failed, they were subsequently replaced with resin-bonded bridges as definitive fixed restorations as the patients were keen to get a fixed restoration as soon as possible and were not keen to pursue another implant. This decision was purely personal and was not influenced by financial constraints.

Prosthodontic outcomes

All of the fixed prostheses maintained stability and function during the evaluation period, with a survival rate of 100% with no failures reported. However, minor complications recorded, such as abutment screw loosening and minimal porcelain chipping, were repaired by polishing and did not require new restorations. There were no occlusal interferences of the crowns registered. The survival analysis for the implant restorations is reported in Table 4.

Table 4 Survival analysis of the implants and crowns
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Periodontal outcomes

An important secondary aim of this study was the evaluation of the soft tissues and periodontal health at the implant sites over the three years. Bleeding on probing measurements revealed low values overall, with the presence in 16% of the sites registered, as did the gingival probing depths, with four implants recording more than 3.5 mm (highlighted in Table 5).

Table 5 Periodontal outcomes (n = 70)
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Aesthetic outcomes

Without exception, all of the patients were delighted with their implant restoration. They were happy to be back to biting into hard foods and they reported an increased confidence in their lives. Unfortunately, an objective index of patient satisfaction was not collected but should be considered in any prospective studies in the future.

Discussion

The overall implant survival rate of 95.7% was comparable with studies reporting implant placement in fresh extraction sites.20,21 In this study, three implants were lost in the central incisor region with all having had a trauma diagnosis of complicated crown-root fractures. The failures may have been a consequence of lower primary stability with reduced available bone at the apical side of the implant. Implant failures in the maxilla have been attributed to the low density of medullary bone and thin cortical plates that are subject to fracture in dental trauma, which could lead to a significant reduction in insertion torque.22,23

Although there were no prosthetic failures reported, biological and technical complications included abutment screw loosening and porcelain chipping. A previous systematic review suggested that screw loosening was not influenced by the geometry of the implant-abutment connection but related to the appropriate torque provided and anti-rotational features.24 Studies have shown that the absence of periodontal receptors may cause excessive load on implant-borne restorations that could result in porcelain chipping.25 The prosthodontic maintenance required in this study was similar to reported rates in the literature and accordingly managed with all prostheses remaining in function throughout the observation period.26

The technique of immediate placement and provisionalisation offers potential advantages for aesthetic outcomes of anterior implant restorations as a result of the preservation of tissue architecture surrounding the crown.27 Important secondary outcomes of the current investigation was to assess the periodontal health around the implants. In accordance with the Periodontology classification guidelines, 22.9% of patients showed bleeding on probing or pocket depths exceeding 3.5 mm as measured from the gingival margin.28 All implants with increased pocket depths survived, with no direct correlation to failures. The periodontal outcomes recorded were similar to those in previous studies and although it was not possible to preclude any longer-term conclusions, the results indicated favourable outcomes within the evaluation period.29,30

Alveolar remodelling following dental trauma can result in considerable bone loss. Implant placements in such sites may compromise position and necessitate the need for further grafting. The results of the present study showed that immediate implants could be placed without the need for an augmentation procedure despite the sequelae of traumatic dental injury incurred. Although patients with signs of periapical pathology at the time of implant placement have been suggested to have a higher risk of complications, this was not shown to have any influence on implant survival. In addition, the relative risk of screw versus cement retention for restoration has often been of interest with regards to peri-implant inflammation. The current investigation used screw-retained crowns without any significant biological complications recorded. Although immediate or early loading could have been utilised, the choice for delayed healing was preferred to optimise primary stability in these cases of previous dental trauma.

As this was a retrospective study, there was reduced control over study parameters and confounding variables compared with a prospective study. Despite this, the study does provide valuable information to practitioners for the use of this approach. Clinical opinion dictates that there can be a far less predictable degree of bone loss following dental trauma depending on the extent of the injury sustained. Despite this, the results demonstrate favourable three-year survival rates comparable to delayed loading in healed extraction sites. Future research assessing aesthetic scores would generate valuable outcomes to optimise these parameters and determine the need for additional soft tissue augmentation.

Conclusion

Within the limitations of the study, the immediate placement of dental implants in fresh extraction sites in the anterior maxilla following cases of dental trauma without bone augmentation has shown to be a safe and predictable treatment modality in the short term. The present protocol offers many advantages in relation to reduction of surgical time and soft tissue healing. Further long-term comparative studies are required to include more detailed analysis of marginal bone loss and aesthetic outcomes to validate this approach.