Journal of Dental Implants

ORIGINAL ARTICLE
Year
: 2014  |  Volume : 4  |  Issue : 2  |  Page : 126--134

Assessment of hard and soft tissue changes around Implants: A clinico-radiographic in vivo study


Jaisika Rajpal1, Krishna K Gupta2, Pradeep Tandon2, Amitabh Srivastava2, Chetan Chandra2,  
1 Department of Periodontology, Subharti Dental College, Meerut, India
2 Department of Periodontology, Sardar Patel Post Graduate Institute of Dental and Medical Sciences, Lucknow, Uttar Pradesh, India

Correspondence Address:
Jaisika Rajpal
45/A, Aashirwad Bhawan, Beside Maittri Niwas Guest House, Krishna Nagar, Kanpur Road, Lucknow - 226 023, Uttar Pradesh
India

Abstract

Introduction: Microbial plaque is the main etiologic factor which causes disease in soft tissue around dental implants. The purpose of this study was to evaluate the bone level around implants using conventional radiography. They were evaluated for radiographic changes in the peri-implant crestal bone at intervals of 1, 3 and 6 months. The radiographic findings were correlated with clinical parameters of mobility, probing depth, bleeding, etc. Aim: The aim of the present study was to evaluate the hard and soft tissue changes around two-stage implant both radiographically and clinically to assess the success of implants. Materials and Methods: Seven patients with 10 dental implants were examined clinically for 6 months after prosthodontic treatment. Plaque index and health indices of soft tissue including pocket depth, mobility, bleeding index, calculus and gingival index were measured. Marginal crestal bone loss and peri-implant radiolucency were checked radiographically. The criteria both subjective and objective were used to evaluate the success of the implant process. The necessary statistical analysis was performed for radiographic and clinical evaluation methods. Results: The results of this study showed that the values of all clinical criteria under study had no significant changes from baseline to 6 months. The vertical crestal bone loss on the mesial and distal side was within the normal range of bone loss given by Brånemark. There was no mobility and no peri-implant radiolucency around any of the implants. Conclusion: Our study clearly demonstrated that in a group of patients with no periodontal disease the survival rate of two-stage, countersunk, submerged implants in the edentulous sites is 100% during the follow-up period of 6 months.



How to cite this article:
Rajpal J, Gupta KK, Tandon P, Srivastava A, Chandra C. Assessment of hard and soft tissue changes around Implants: A clinico-radiographic in vivo study.J Dent Implant 2014;4:126-134


How to cite this URL:
Rajpal J, Gupta KK, Tandon P, Srivastava A, Chandra C. Assessment of hard and soft tissue changes around Implants: A clinico-radiographic in vivo study. J Dent Implant [serial online] 2014 [cited 2019 Sep 17 ];4:126-134
Available from: http://www.jdionline.org/text.asp?2014/4/2/126/140863


Full Text

 INTRODUCTION



The clinical replacement of lost natural teeth by osseointegrated implants has represented the most revolutionary advancement in restorative dentistry. [1] The use of endosseous implants to restore lost dentition has proved to be a successful treatment modality, providing the patient with near natural replacement. Implants have become the treatment of choice in many, if not most, situations when missing teeth require replacement. [2] Many implant designs have been developed by various companies to achieve a greater degree of osseointegration. The original Brånemark protocol calls for a two-stage approach where in, the implant is placed at the first-stage, countersunk to a subcrestal position and covered with tissue during the osseous healing period. Reasons for using this approach are to minimize the risk of infection, prevent apical growth of the mucosal epithelium, and minimize the risk of undue early transmucosal loading. [3],[4],[5]

It is important to remember that implants only replicate natural teeth and that the implant-mucosa-bone interface only approximates the natural periodontium. Lack of cementum and periodontal ligament, less vasculature and fibroblasts, a parallel orientation of supracrestal connective tissue, and the subgingival location of crowns make the implant structures more susceptible to the development of inflammation and bone loss when exposed to plaque accumulation or microbial invasion. [6],[7] The success rate obtained with dental implants depends to a great extent on the quality of oseointegration. The early identification of signs and symptoms of bone loss is, therefore, essential to prevent implant loss. [8]

Radiographic analysis has shown that the largest amount of bone loss occurs following implant placement and abutment connection. [9] Typically, there are no significant marginal bone changes during functional loading. [10] Criteria for successful implant therapy include a median marginal bone loss of 0.5 mm during healing, followed by an annual rate of vertical bone loss of <0.2 mm a year. [3] The level of the bone crest surrounding the implant is of utmost significance to determine osseointegrated implant success, [11] as preservation of marginal bone height is highly important for long-term dental implant survival. [12] Anatomic factors, such as the quality and architecture of bone tissue, as well as implant features, e.g. length, surface area, coating, implant timing [11] and occlusal load [13] may influence alveolar bone crest resorption. Longevity is the most common parameter to evaluate the success of dental implants, and the maintenance of cervical bone around the implant is the main factor to determine such a positive outcome. [11]

Apart from radiographic evaluation of crestal bone loss some clinical parameters are also used to assess the peri-implant soft tissue. The parameters used routinely during maintenance of patients treated with implants should be sensitive enough to allow discrimination of early changes. Criteria such as absence of mobility, reduction of probing depth, absence of suppuration, decreased bleeding on probing (BOP) and least amount of local deposits are all important in assessing the success of implants. [12]

Consequently, the present study was undertaken to evaluate the bone level around implants using conventional radiography. They were evaluated for radiographic changes in the peri-implant crestal bone at intervals of 1, 3 and 6 months. The radiographic findings were correlated with clinical parameters of mobility, probing depth, bleeding, etc., The criteria both subjective and objective were used to evaluate the success of the implant process. The necessary statistical analysis was performed for radiographic and clinical evaluation methods.

Aim and objectives

The aim of the present study was to evaluate the hard and soft tissue changes around two-stage implant both radiographically and clinically to assess the success of implants.

The present study was done with the objectives:

To assess the implant success of two-stage, submerged implant placement with delayed loading in the mandibular archTo establish function, esthetics and phonetics with implant restoration in the partial edentulous regionsTo evaluate clinically and radiographically, the changes in the alveolar crestal bone height and soft tissues around the implants at an interval of the baseline (placement of the definitive restoration), 1 st , 3 rd and 6 th month.

 MATERIALS AND METHODS



Patients desirous of replacement of missing teeth were selected amongst the outpatient Department of Periodontology and Implantology, Sardar Patel Post Graduate Institute of Dental and Medical Sciences, Lucknow. The criteria for inclusion of subjects in the study were patients with tooth loss, an adequate amount of bone volume and bone density to accommodate an implant of appropriate dimensions, healthy, sufficient and stable soft tissue architecture, edentulous sites free from infection, intact, restored, calculus free and periodontally stable adjacent teeth and patients willing to follow recommended plaque control and follow-up regimen. Subjects with any medical or surgical co-morbidities were excluded from the study.

The Equinox_Uniti™ root form and threaded implant system with cortico-cancellous design and selective integrated surface (sand-blasted and acid etched surface) with gold on carbon coatings were used. These are two piece implants were made of commercially pure bio-grade titanium.

The study comprised of seven patients (3 males and 4 females, in which at 10 sites implants were placed) aged from 20 to 55 years were selected for implant placement.

The pretreatment record of the patient included the detailed medical and dental history, informed verbal and written consent, periodontal assessment using clinical parameters, diagnostic casts, radiographic stent and surgical stent [Figure 1], periapical and panoramic radiographs, computed tomography scans (Dentascans) were taken where ever necessary to identify the anatomical landmarks and bone volume at questionable sites, clinical photographs and identification of anatomic landmarks in relation to implant site [Figure 2] and [Figure 3].{Figure 1}{Figure 2}{Figure 3}

On the day of surgery after achieving adequate local anesthesia, crestal incisions were placed on the edentulous site and full thickness flaps were elevated using a periosteal elevator. Drilling of the osteotomy site was done with the help of stent [Figure 4]. The osteotomy was generously irrigated with sterile saline to ensure debris free site [Figure 5]. Implants of decided dimension were placed at a speed of 20-30 rpm. During implant placement, care was taken for the correct angulation of placement [Figure 6]. All implants were placed with primary stability and were completely housed within the implant osteotomy, and cover screw was placed [Figure 7]. The flap margins were then repositioned and sutured tension free applying simple interrupted and/or simple mattress lock sutures with a 3'o braided silk suture. Patient was then advised to follow standard postoperative instruction, which includes ice packs, soft high nutrient diet, postoperative medications which consisted of appropriate antibiotic (amoxicillin 500 mg, 4 times daily), analgesic (ibuprofen 400 mg, every 4-6 h as needed for pain) were prescribed. Patients were instructed not to brush the surgical site, but rather to rinse with 0. About 2% chlorhexidine gluconate. After about 7-10 days, sutures were removed. The patients were then followed-up postoperatively at 1 st day; 1 week, 15 days, 1 st month, 3 rd month and 6 th month thereon and required investigations were done whenever needed.{Figure 4}{Figure 5}{Figure 6}{Figure 7}

Three-four months after implant placement, second-stage surgery was initiated. Mid crestal incision was placed, and flap was reflected. Cover screw was removed and gingival former [Figure 8] was placed for a period of 15 days. This resulted in the formation of a gingival cuff or gingival collar. Gingival former was removed with the help of 0.50 hex driver, abutment was placed over the implant and screw was tightened [Figure 9]. After the laboratory fabrication of porcelain fused to metal crown, the prosthesis was cemented over the abutment [Figure 10] and [Figure 11]. Patients were reviewed at 1 st month, 3 rd month and 6 th month with evaluation of all clinical and radiographic parameters. The following clinical parameters were recorded:

BOP by bleeding index of Mombelli and Lang [12]Gingival inflammation by gingival index of Silness and Loe [14]Plaque accumulation by plaque index of Mombelli and Lang [12]Probing depth was calculated using plastic probe on mesial, distal, lingual and buccal sites and then the mean probing depth was calculated [Figure 12]Calculus was examined clinically by physical manipulation and visual scale for presence or absence on mesial, distal, buccal and lingual surfaces and scored using binary figures of 0 and 1Implant mobility was assessed by clinical implant mobility scale of Misch and Silc [15] two rigid instruments were used to apply a labiolingual force of approximately 500 g.{Figure 8}{Figure 9}{Figure 10}{Figure 11}{Figure 12}

For the evaluation of the radiographic criteria intra oral periapical radiographs were taken with long cone paralleling technique, using extension cone paralleling device with exposure time of 0.8 s and the following radiographic parameters were evaluated:

Marginal bone loss (in mm) of each implant was assessed by periapical radiograph examination. The marginal bone height of each fixture was measured mesially and distally by using the fixture threads as an internal dimensional reference with the help of a milimetric grid [Figure 13]. Marginal bone loss was measured by measuring the distance from the first thread (coronal) on the implant fixture to the most coronal point on the mesial and distal alveolar bone crest respectively. Intraoral periapical radiographs were taken at baseline, 1 st , 3 rd and 6 th month's intervalPeri-implant radiolucency was assessed on an undistorted radiograph as present or absent.{Figure 13}

All the recorded clinical and radiographic parameters were entered in the standard performa drawn for this study and subjected to statistical analysis.

Statistical analysis

Groups were compared by repeated measure one way analysis of variance, followed by Turkey's post hoc test. [16] Groups were also compared by independent Student's t-test. Pearson correlation analysis was used to assess the association between the variables

Observations

Seven patients had 10 implants placed at single or multiple mandibular edentulous sites. The age of the subjects in the study ranged between 20 and 59 years. The sex distribution was equal with 50% implants in males and 50% in females. The length of the implants placed varied in different subjects, with as many as eight implants having 13 mm length, one implant was 10 mm and remaining one was 15 mm. The diameter of the implants also varied with three implants having diameter of 3.3 mm, 1 with 3.7 mm, 4 with 4.3 mm and 2 with a diameter of 5.3 mm.

Clinical parameters

The scores of plaque index of all subjects at baseline, after 1, 3 and 6 months ranged from 0 to 1, 0 to 1, 0 to 0.75, and 0 to 0.50 respectively with mean (±standard deviation [SE]) 0.48 ± 0.14, 0.55 ± 0.11, 0.50 ± 0.08 and 0.30 ± 0.06 respectively [Graph 1 [SUPPORTING:1]]. Comparing the mean plaque index between different periods, the plaque index did not change significantly (P > 0.05) that is, a change in plaque index at different periods remains statistically the same. Comparing the mean BOP between different periods, the BOP decreased significantly (P < 0.05 or P < 0.01) by 29.6% after 3 months (0.68 ± 0.12 vs. 0.48 ± 0.10, q = 4.619; P < 0.05) and 33.3% after 6 months (0.68 ± 0.12 vs. 0.45 ± 0.10, q = 5.196; P < 0.01) as compared to after 1 month while in other periods it did not change significantly (P > 0.05) that is, found to be statistically the same [Table 1]. As compared to baseline, gingival index of all subjects increased by 15.0% after 1 month while decreased by 5.6% and 25.0% respectively after 3 months and after 6 months [Graph 2 [SUPPORTING:2]]. Comparing the mean gingival index between different periods, the gingival index decreased significantly by 34.8% after 6 months (0.58 ± 0.12 vs. 0.38 ± 0.11, q = 4.942; P < 0.01) as compared to after 1 month, while in other periods it did not changed significantly (P > 0.05) that is, found to be statistically the same. Comparing the mean probing depth between different periods, the probing depth increased significantly by 25.7% after 6 months (1.85 ± 0.20 vs. 2.33 ± 0.21, q = 4.618; P < 0.05) as compared to baseline while in other periods it did not changed significantly (P > 0.05) that is, found to be statistically the same [Graph 3 [SUPPORTING:3]] and [Table 2]. The calculus scores of all subjects at baseline, after 1, 3 and 6 months ranged from 0 to 0, 0 to 0.25, 0 to 0.75 and 0 to 1, respectively with mean (±SE) 0.00 ± 0.00, 0.08 ± 0.04, 0.18 ± 0.08, and 0.25 ± 0.13, respectively. No mobility of the implant was found at the level of 1, 3 and 6 months interval from the baseline which shows 100% stability.{Table 1}{Table 2}

Radiographic parameters

The crestal bone loss of all subjects at baseline, after 1 month, after 3 months and after 6 months ranged from 0 to 0, 0 to 1.5, 0.25 to 1.50, and 0.25 to 1.75 respectively with mean (±SE) 0.00 ± 0.00, 0.58 ± 0.16, 0.90 ± 0.16, and 1.13 ± 0.14 respectively [Table 3] and [Graph 4 [SUPPORTING:4]]. Comparison of the mean crestal bone loss between different periods is depicted in [Table 3]. On comparing, postimplant mesial (P < 0.001) and distal (P < 0.05 or P < 0.001) both showed significant increase in bone loss at 1 month, 3 months and 6 months when compared to preimplant (baseline). No peri-implant radiolucency was found at the level of 1, 3 and 6 months interval from the baseline.{Table 3}

 DISCUSSION



The concept of osseointegration was described by Brεnemark (1977) that led to the predictable success of oral implants to replace missing teeth in edentulous patients. Long-term clinical studies since then indicate that a successful osseointegration and restoration of implants are the expected therapeutic outcomes. [17]

A rationale for choosing a two-stage, submerged surgical approach and delayed loading period in our study was to reduce and minimize the risk of bacterial infection, to prevent apical migration of the oral epithelium along the body of the implant, and to reduce and minimize the risk of early implant loading during bone remodeling as premature micro motion will repeatedly disrupt the normal osseous modeling processes leading to fibrous tissue encapsulation rather than direct bone apposition around the implant. [18],[19]

Plaque is considered as an important etiological factor in peri-implantitis. There was an increase in plaque accumulation from baseline to 1 st and 3 rd month, but there was a subsequent decrease in plaque from 1 st to 6 th month. This can be attributed to the plaque control by the patient and the repeated reinforcements of oral hygiene measures given to the patient by the clinician. However, the reduction was not statistically significant (P > 0.05) that is, a change in plaque index at different periods remained statistically the same, which was similar to the earlier studies conducted by Behneke et al. [20] and Kan et al. [21]

Bleeding on probing (probing in the depth of the pocket until a, slight resistance is met) and gingival index are one of the periodontal parameters used to evaluate the presence of an inflammatory process at the base of the periodontal pocket. There was an increase in BOP and gingival index from baseline to 1 st month, but there was a subsequent decrease in BOP from 1 st to 6 th month. This can be attributed to the fact that after loading the implant hygiene could not be well maintained in the subgingival regions, but later when the repeated reinforcements of oral hygiene measures were given to the patient the inflammation subsided and so did BOP. However, the reduction was not statistically significant (P > 0.05) that is, a change in bleeding and gingival index at different periods remains statistically the same, which were in agreement with the earlier studies conducted by Blanes et al., [22] Lekholm and van Steenberghe [23] and Rismanchian and Fazel. [24]

In a study by Bauman et al., probing proved to be the most-accurate means of detecting peri-implant destruction. He suggested using radiographic and probing measurements together to facilitate the accuracy and variability of comprehensive peri-implant assessment. [25] The mean probing depth at baseline, 1 st , 3 rd and 6 th months were 1.85 ± 0.20 mm, 2.03 ± 0.21 mm, 2.15 ± 0.19 mm, and 2.33 ± 0.21 mm respectively. Clinical studies have demonstrated that failing implants caused by recurrent peri-implant infections are always associated with increased peritoneal dialysis (PD). In our study, the mean PD revealed a slight increase over time. This is in agreement with other reports by Behneke et al., Joly [26] and Buser et al. [27] However, the PD alone is not reliable enough to follow the peri-implant soft tissue levels over time, since it can be influenced by changes in the gingival anatomy. [28]

Calculus was measured as binominal scores of 1 - Present and 0 - Absent. Very minute amount of calculus was present in few implants. Only a significant increase was seen from baseline to 6 th month. The results were comparable to the study by Heydenrijk et al. which concluded that the calculus formation in two-stage implants is due to the occurrence of Bacteroides forsythus and Prevotella intermedia. [4]

Primary stability at the time of implant placement has been recognized as an important prerequisite for the achievement of osseointegration. Implant mobility is an indication of lack of osseointegration. All the implants evaluated in our study at 1 st month, 3 rd month and 6 months did not show any amount of mobility. This is in accordance to the studies conducted by Behneke et al. [20] and Kan et al. [21]

Originally, a mean crestal bone loss ≥1.5 mm during the 1 st year after loading and ≥0.2 mm/year thereafter had been proposed as one of the major success criteria. The highest marginal mean bone level in our study was 1.13 mm at 6 months interval.

The lowest marginal mean bone level noted was 0.58 mm at 1 st month after loading. The maximum percentage increase in bone loss from baseline to 6 th month was 95.7%. However, the crestal bone loss in other periods did not differ significantly (P > 0.05) that is, found to be statistically the same. These results were in accordance with previous researches by Kan et al. 2003 and Buser et al. [27] Although the marginal bone loss in our study was well within the range given by Albrektsson et al. 1986, it was higher than the accepted mean marginal bone loss in studies by Behneke et al. 1997 and Lekholm and van Steenberghe 1994. This difference in the results could be due a variety of factors stated by Misch. [29] Like reflection of the periosteum during surgery, preparation of the implant osteotomy, bacterial invasion, level of micro gap between the abutment and implant body, establishment of a biologic width, the implant crest module design and occlusal overload.

Complete peri-implant radiolucency indicates the presence of soft tissue and probable implant mobility and is a predictor of implant loss. Evaluation of the properly made serial radiographs for peri-implant radiolucency was, therefore, done in our study for determining clinical success. Albrektsson et al. 1986 quoted that clinical symptoms such as spontaneous pain BOP and peri-implant infection are signs of failing implant during the maintenance period. There was no evidence of peri-implant radiolucency at any given interval time. van Steenberghe [30] also proposed that there should be no peri-implant radiolucency on undistorted radiograph for success of the implant.

 CONCLUSION



The following conclusions were drawn from the study which was done to evaluate the hard and soft changes along with the survival rate of Uniti; dental implants choosing a two-stage submerged, surgical approach and delayed loading period. Plaque index, BOP, gingival index decreased over the entire 6 months period and was co-related with the other clinical parameters. Probing depth around implants at mesial, buccal, distal and lingual surfaces increased from baseline to 6 months, but this increase was nonsignificant. Calculus increased significantly from baseline to 6 th month. All the implants were immobile at the end of 6 months period, with Grade 0 mobility. Radiographic evaluation of intraoral periapical radiograph of the implant at mesial and distal sites revealed significant decrease in bone height indicating bone remodeling around the implant. No radiographic peri-implant radiolucency was seen around any of the implants. This concludes that the osseointegration can be achieved if the implants are placed in with a delicate surgical technique and are allowed to heal without load for a period not <3-6 months. Our study clearly demonstrated that in a group of patients with no periodontal disease the survival rate of two-stage, countersunk, submerged implants in the edentulous sites is 100% during the follow-up period of 6 months. Possible explanations may be proper case selection, diagnosis, aseptic method of surgery, maintenance of sufficient cortical bone around the implant and good oral hygiene maintenance during the follow-up period. In order to increase our understanding, studies need to be conducted with longer duration and a larger sample size.

 ACKNOWLEDGMENTS



Dr. Vinod Kumar, Dr. Vijendra Singh, Dr. Ruchi Srivastava, Dr. Ajay Singh and Dr. Ruchika Prasad for their unending support in the project.

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