Journal of Interdisciplinary Dentistry

ORIGINAL ARTICLE
Year
: 2016  |  Volume : 6  |  Issue : 3  |  Page : 128--134

Implant stability measurements using resonance frequency analysis and radiographic evaluation of crestal bone loss in indigenously developed implants placed in fresh extraction sockets


Aman Sachdeva1, Pankaj Dhawan1, Pankaj Madhukar1, Sugandha Gupta1, Aakanksha Bhardawaj2,  
1 Department of Prosthodontics, Manav Rachna Dental College, Faridabad, Haryana, India
2 Department of Periodontics, DAV Dental College, Yamuna Nagar, Haryana, India

Correspondence Address:
Sugandha Gupta
Department of Prosthodontics, Manav Rachna Dental College, Faridabad, Haryana
India

Abstract

Objectives: This study aimed to measure the stability and crestal bone level changes of indigenously developed implants in fresh extraction sockets. Materials and Methods: Forty implants were placed immediately in fresh extraction sockets in 27 patients in the age group of 18–65 years. Clinical assessment of stability was made using resonance frequency analysis (RFA) at the time of placement of implant at 3, 6, and 12 months postoperatively, and radiographic crestal bone changes were evaluated using digital radiograph at 0, 6, and 12 months. The distance between the first visible bone-implant contact and implant shoulder was measured, and crestal bone loss was calculated. Results: The mean RFA values obtained were 48.08 ISQ at the time of placement and reached 66.32 ISQ after a follow-up period of 12 months. The mean radiographic bone loss was 0.67 mm at the end of 12 months. The results emphasized that there was no significant bone loss. Out of forty dental implants, two failed in the early phase. Thus, the survival rate of implants placed in fresh extraction socket was 95% at the end of 12 months. Conclusion: Immediate placed implants can attain adequate level of primary stability. These stability levels improve with time, reaching similar values irrespective of the initial stability. About 50% of mean crestal bone loss occurred during the first 6 months after implant placement suggesting several factors other than occlusal load affecting bone levels around implants. The present study also finds a negative correlation between the crestal bone loss and stability values in terms of ISQ at a statistically significant value. Clinical Relevance to Interdisciplinary Dentistry Dental implants represent one of the most successful treatment modalities in modern dentistry. A multidisciplinary approach comprising surgical, prosthetic, and periodontal treatment was done to achieve a satisfactory result. Achievement and maintenance of implant stability is the most critical factor for successful clinical outcome.



How to cite this article:
Sachdeva A, Dhawan P, Madhukar P, Gupta S, Bhardawaj A. Implant stability measurements using resonance frequency analysis and radiographic evaluation of crestal bone loss in indigenously developed implants placed in fresh extraction sockets.J Interdiscip Dentistry 2016;6:128-134


How to cite this URL:
Sachdeva A, Dhawan P, Madhukar P, Gupta S, Bhardawaj A. Implant stability measurements using resonance frequency analysis and radiographic evaluation of crestal bone loss in indigenously developed implants placed in fresh extraction sockets. J Interdiscip Dentistry [serial online] 2016 [cited 2020 Jan 18 ];6:128-134
Available from: http://www.jidonline.com/text.asp?2016/6/3/128/201648


Full Text

 Introduction



Developments of newer materials, techniques in dentistry, and the advent of osseointegration by Branemark [1] have led to a treatment approach which can provide a suitable restoration or prosthesis for replacing a missing tooth. As implants gained popularity, clinicians focused on the treatment modality to shorten the period and number of surgical interventions. This leads to the surgical concept of implant placement in fresh extraction sockets. The concept was first advocated by Schulte et al.,[2] and the first documented human case was published by Lazzara [3] in 1989.Dental implants represent one of the most successful treatment modalities in modern dentistry; still failures occur in the range of 5%–8% for routine procedures.[4],[5],[6] Hence, achievement and maintenance of implant stability is the most critical factor for successful clinical outcome.[7] The stability of an implant can be defined as the implant's capacity to withstand loading. Implant stability is also regarded as an indirect indication of osseointegration and is a measure of implant's resistance to movement.[8],[9],[10]

In the late 1990s, Meredith [11] suggested a noninvasive method of analyzing peri-implant bone stability, which was based on resonance frequency analysis (RFA). It is a noninvasive, quantifiable method, which is considered the gold standard for clinical stability and allows for objective decision-making and appropriate modification of treatment protocols.[12],[13]

Successful implant therapy needs implant to be maintained in a stable state. Implant stability is affected by factors such as bone loss around implants.[10],[12],[14] The marginal bone loss around an implant, if continues for several years, may jeopardize the implant outcome.[15] The plausible etiological factors considered to cause bone loss include surgical trauma, occlusal overload, peri-implantitis, microgap, biological width, and implant crest module.[16],[17],[18],[19],[20],[21] The most common clinical tool to measure this marginal peri-implant bone resorption is through radiographic measurement. The intraoral radiographic technique permits adjustment of the X-ray beam angulation and provides a high resolution.[22]

The present research work was an attempt to study indigenously developed dental implants clinically in demanding situations such as placement of implants immediately in fresh extraction sockets and evaluating the stability and crestal bone changes for a period of 12 months.

 Materials and Methods



This clinical study was conducted in Department of Prosthodontics and Crown and Bridge, Manav Rachna Dental College, Faridabad. Forty implants were placed immediately in fresh extraction sockets in 27 patients in the age group of 18–65 years [Figure 1]. Clinical assessment of stability was made using RFA analysis “OSSTELL ISQ,” and radiographic crestal bone changes were evaluated using digital intraoral radiographs.{Figure 1}

Patient selection, implant fixture placement, and follow-up were done between January 2013 and September 2014, and all patients were treated following the “T1” approach of Hammerle et al.

Primary stability was recorded using RFA with Osstell ISQ instrument and SmartPeg type 47. Two readings were recorded, one in the buccolingual direction and the other in the mesiodistal direction. Implants were restored with the delayed and progressive loading approach with provisional restoration at 3–6 months after implant placement surgery. Provisional crowns were given for a period of 2 weeks and were followed by a PFM crown. RFA values were kept as the baseline for provisional restoration. Provisional restorations were delayed in cases where the RFA values were recorded lower than 50 ISQ at the time of prosthetic connection.

RFA measurements were performed at implant insertion, 3, 6, and 12 months (prosthesis attachment 3–6 months). At each measurement session, the crown/restoration was removed to give access to each single implant. Standardized parallel radiographs were taken in [Figure 2] and [Figure 3] and analyzed with Digimizer image analysis software to evaluate crestal bone changes.{Figure 2}{Figure 3}

 Results



A total of 40 implants were placed immediately following tooth extraction in fresh extraction sockets in 27 patients. Thirty-four implants were placed in the mandibular molar region, and six implants were placed in the maxillary anterior and premolar region. Clinical data were collected systematically and entered into an Excel sheet (Office 2010) for analysis. All statistical analyses and computations were performed using Statistical Package for Social Sciences software version 22.0 (SPSS Statistics V 22.0, IBM, United States). Mean values and standard deviations (SDs) were calculated for ISQ values and radiological crestal bone level changes. RFA values and crestal bone level loss were compared for subgroups. The data were subjected to descriptive analysis for the calculation of mean, SD, and percentages. The Student's t-test was used, and a P ≤ 0.05 was considered to be statistically significant at 95% confidence interval.

During the observation period of 12 months, two implants failed in the early phase of healing. Based on the success parameters, the survival rate of dental implants when placed in immediate extraction sockets was calculated to be 95%. The overall mean RFA measurements at the time of implant insertion were calculated to be 48.08 ISQ (SD 8.82); at 3 months following, implant insertion was calculated to be 52.18 ISQ (SD 6.86); and at 6 and 12 months following, implant insertion was calculated to be 60.53 (SD 12.55) and 66.32 ISQ (SD 2.88), respectively.

Radiographic evaluation of the patients receiving immediate implant therapy revealed that mean crestal bone resorption was 0.34 and 0.67 mm at 6 and 12 months, respectively.

The overall mean RFA measurements and crestal bone level changes are shown in [Figure 4],[Figure 5],[Figure 6] and [Table 1].{Figure 4}{Figure 5}{Figure 6}{Table 1}

 Discussion



In this study, two implants failed in the early healing period and before bony osseointegration, thus making the success rate of 95% of the “indident” implants; this is comparable to the success rate of 92%–100% mentioned in the published literature.[4],5,[23],[24],[25],[26] Interestingly, several clinical studies have also found that the survival rate of immediate implants was comparable to healing or healed sites. Lindeboom et al.[27] in a randomized controlled trial reported that the survival rate for immediate implants was 92% as compared to 100% for delayed implant placement.

The placement of immediate dental implants in the presence of a periapical or periodontal infection has been contraindicated by many authors.[4],[27],[28],[29] Esposito et al.[30] in a Cochrane review suggested that immediate implant placement might be at higher risk of implant failures and complications than delayed implants. Studies suggest that periodontitis as a reason for extraction may adversely affect implant survival.[28],[29] Contrary to these findings, several published studies in both animal jaws, long bone, and human trials have shown that periodontal or periapical lesions did not affect the ability for implants to predictably osseointegrate.[23],[31],[32],[33],[34],[35] Siegenthaler et al.[33] treated 17 patients consecutively who had periapical lesions using immediately placed roughened surface implants observed for 12 months with a success rate of 100%. The authors concluded that a critical aspect of treatment was to assess the diameter of the periapical lesion. The higher success rate of implant placement in fresh extraction socket placed in endodontic infections may also be explained by the fact that they are mixed infections dominated by anaerobic bacteria which are restricted in the infected root canal, and extractions of the tooth generally lead to the eradication of cultured microorganisms.[27],[36],[37],[38] Thus, within the limitation of the present study, it can be concluded that immediate implant placement in teeth having periapical lesions is a predictable treatment option.

The present study shows that implants placed in the fresh extraction sockets can achieve and maintain adequate level of stability. Dental implants longer than the length of extraction sockets were placed so as to engage 3–5 mm of bone apical to the socket to achieve primary stability. The result of the present study is in line with the literature.[39] Research conducted by Rabel et al.[39] showed that ISQ values of 57–82 at 1-year indicate implant success. Although several factors can influence primary stability, the implant placement in fresh extraction sockets always has a bone defect at the marginal region which are mostly present in the buccal and lingual aspects of the implant, and it might have an effect on the initial measurement of stability.[40] Primary stability is also influenced by the presence and absence of cortical bone as cortical bone is 10–20 times stiffer than trabecular bone.[8],[41] In most cases of immediate implant placement, primary stability is gained through the apical trabecular bone as there is a jumping distance between the implant and marginal bone, and intimate contact is not frequently achieved, thereby affecting stability readings.[40] The present study found that irrespective of the primary stability values, implants stability reached the same level after 1 year. It was also noted that implants placed in the maxilla and mandible had similar values of implant stability, and no statistical difference was found in the ISQ values. It was found that in certain situations where initial stability was low, a longer period was required to reach stability values suitable for loading. This finding is in line with that of Guler et al.,[42] which suggests that immediate implant placement may have a slower osseointegration rate than delayed implant placement. The present study also validates the presence of negative correlation of crestal bone loss and ISQ readings at a statistically significant value, suggesting that stability level decreases with loss of crestal bone around implants in the initial 1-year follow-up period. This is in line with Sennerby and Meredith [10] and Meredith [11] who suggested that variations in implant stability could be explained by differences in the marginal bone height.

In this study, almost 50% of the bone loss occurred during the first 6 months of implant placement, suggesting that there are several factors which affect the crestal bone changings other than occlusal overload, and it could be influenced by surgical trauma, bone remodeling after implant placement. This radiological finding is in accordance with other research findings in the literature, which states that most of the bone loss occurred during the first few months following immediate implant placement.[43],[44],[45],[46],[47] Vidal et al.[43] evaluated transmucosal implants placed immediately in the extraction sockets. The mean 1st year bone loss observed was 1.3 mm. It was observed that the greatest bone loss occurred between the time of implant placement and 4 months, postimplant placement. Cavallaro [44] suggested that crestal bone level changes around implants may be because of the surgical procedure, remodeling, and formation of biological width, local factors such as bone quality and quantity proximity to adjacent teeth or implant. Studies have reported that the implant placement in the fresh extraction socket failed to counteract buccal ridge alteration following tooth loss and sites with immediate implants placed reported 50% of the original buccal plate width undergoing resorption.[48] The width of the buccal and lingual bone wall diminishes over time and in particular the height of the buccal wall reduces. In the present study, digital radiography was used to assess bone level changes. It is a two-dimensional radiographic technique and offers analysis of mesial or distal sites and does not reveal buccal hard tissue changes. Therefore, it is suggested that further studies can use 3D radiographic imaging to evaluate volumetric bone changes around immediate implants.

Resonance frequency analysis measurements and implant failure

In this study, 38 implants showed increasing stability values with time, except for the two failing implants. Immediate implant placement showed adequate levels of implant stability in forty cases. The mean primary stability was noted to be 48.08 ISQ; however, in more than 60% of cases, initial stability was 55 ISQ, and 1-year postplacement, mean implant stability was noted to be 66 ISQ. The two failures were found to be associated with low initial stability values or marked decrease in stability values in case of high initial stability.

It was noted that on four occasions, initial stability was lower than 35 ISQ, out of which one implant failed. In another case, after a healing period of 2 months, the implant showed lateral mobility, but on reinforcement of oral hygiene instructions, the implant fixture showed an increase in ISQ values and survived. Out of the two implant failures, one occurred at the maxillary lateral incisor site and the other at the mandibular first molar site. It was documented that primary stability was adequate at the time implant was placed at the maxillary lateral incisor extraction socket, but the adjacent tooth had periapical pathology, and follow-up after 3 months showed a decrease in stability, and on subsequent follow-up appointment, the implant showed rotational mobility. The literature has documented high risk of implant failure when placing implants adjacent to teeth with periapical pathology.[49],[50],[51] Therefore, it could be asserted that the presence of preexisting periapical pathology in the adjacent tooth was one of the possible reasons for implant failure.

In the other clinical case of implant failure, it was noted that the questionable tooth had periodontal infection as a reason for tooth extraction, and the primary stability was low at the time of insertion. Studies suggest that implants placed in periodontally infected sockets in general have low primary stability which can affect the overall treatment outcome.[52] Several studies have reported that implants with ISQ value <47 ISQ are at a higher risk of failure, and implants with stability of 57–82 ISQ are considered safe for loading.[39],[53]

However, in the implant failure at 12 sites that is maxillary right lateral incisor, primary stability was adequate, and two implants were placed in the same patient following the same surgical technique in anterior maxilla though implant which had an adjacent tooth with periapical pathology showed progressive and marked stability loss from 55 to 41 ISQ in the initial months and further decrease in stability till the implant showed rotational mobility. Therefore, it could be asserted that marked and continuous loss in ISQ readings also has a profound effect on the outcome as is that of low ISQ readings.

It can be highlighted that primary implant stability depends on many factors such as local bone quality and quantity, implant morphology, and the surgical technique followed.[7],[11] As implant length, width, surface, and number of threads are very specific for a particular implant system, therefore RFA values are not comparable for different implant systems.[10],[52] These values should be individually determined for each implant system and are in a similar pattern for a particular implant system in a specific clinical situation.[10],[52] Although low ISQ values are considered to be a factor precipitating implant failure,[54] however Tözüm et al.[55] and Glauser et al.[56] suggested that marked and progressive decline in ISQ values is equally an risk factor associated with implant failure. Thus, RFA measurements have predictive values for stability when used repeatedly over a longer period of time.[39]

 Conclusion



The study showed that indigenously developed implants can be placed predictably in fresh extraction socket with a survival rate of 95% in the 1st year. Implants reached overall good stability levels, and the amount of crestal bone loss was small. The authors further suggest that implants, surgical techniques, and local bone conditions are the main determinants of RFA readings in particular situations, which can vary greatly in different patients and studies; therefore, inference from different studies should be interpreted accordingly.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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