Evaluation of peri-implant soft tissue and bone levels around early loaded implant in restoring single missing tooth: A clinico-radiographic study.

BACKGROUND: One-stage nonsubmerged protocol which can achieve success rates comparable to implants placed in a two-staged submerged procedure also the preconditions for periimplant bone regeneration has lead to more refined concepts of implant loading.
MATERIALS AND METHODS: Twenty sites with single missing tooth were included in this study. Clinical parameters included sulcus bleeding index (sBI), probing pocket depth (PD), and papilla index (PI) and radiographic parameters included crestal bone level were assessed for a period of 9 months.
RESULTS: The crestal bone loss showed mean value ranging from baseline 0.25 ± 0.11 to 0.31 ± 0.08 at 3 weeks, to 0.67 ± 0.13 at 3 months, to 0.85 ± 0.09 at 6 months, and to 0.88 ± 0.12 at 9 months. Probing PD, the mean value for probing PD at 3 weeks 1.20 ± 0.83, 3 months 1.60 ± 1.1, at 6 months 1.40 ± 1.14, and at 9 months 1.20 ± 1.0. sBI, mean value for sBI at 3 weeks 0.00 ± 0.00, 3 months 0.3 ± 0.11, at 6 months 0.09 ± 0.25, and at 9 months 0.08 ± 0.24. PI, showed a significant difference among at different points of time with P = 0.000.
CONCLUSION: The dental implants showed <1 mm of crestal bone loss at 9 months follow-up, clinically significant marginal bone loss occurred between the time of implant placement and 3 months. Subsequent to that, bone loss observed around the implant up to 9 months was minimal. The periimplant soft tissue maturity was maintained throughout the study.

INTRODUCTION

lthough osseo-integration is a prerequisite for long-term implant stability, the proper soft tissue seal to the titanium surfaces at the most coronal aspect of the implant body is required to prevent pathology that may interfere with osseo-integration process.[1] Dental implants can be categorized based on many different things – by size, by material used, by type of connection on top of the head of the implant, and by the stages of the treatment, the last one being the most common. Based on the stages of the treatment dental implants are divided into - Two stage: The implant heals under the soft tissue and is, after a healing period, accessed through a second-stage surgery,[2] One stage: The implant heals without protection of the oral mucosa and is accessible through the mucosa during healing time.[1] The placement of implants in a one-stage procedure has some advantages such as only one surgical intervention is needed,[2] treatment time is shorter, and the implants are accessible for clinical monitoring during the healing phase,[1] and it provides a transmucosal extension that guides healing soft tissue.[2] Interlocking between the implant surface and adjacent bone at the time of implant placement has to be transformed into a biological type of anchorage through the osteo-conductive bone formation at the interface during bone healing. This constitutes a critical period in all accelerated loading protocols.[3]

MATERIALS AND METHODS

A total of 20 patients for the proposed study were selected from the Out Patients Department of Periodontics and Oral Implantology, Santosh Dental College and Hospital, Ghaziabad. Each patient was given a detailed verbal and written description of the risks and benefits of the proposed treatment. They were required to sign a consent form prior to the procedure. Patients in the age range 18–50 years having a single tooth missing site with the presence of adjacent and opposing teeth intact, restored with functionally and esthetically good restorations and the patients with a good periodontal and general systemic health were included in the study. Patients with a history of smoking and who were unable to perform routine oral hygiene procedures, patients with psychosis or dental history of bruxism and parafunctional habits and who were contraindicated for periodontal surgery were excluded from this study. Pretreatment records such as detailed medical and dental history, periodontal assessment using clinical parameters, diagnostic cast, radiographs such as periapical radiographs, panoramic radiographs were taken, clinical photographs, surgical templates, and identification of anatomic landmarks in relation to implant site were done.

Following the inclusion and exclusion criteria, the selected patients were explained about the nature and surgical procedure in detail, the purpose of the study and were made to sign an informed consent as a part of protocol requirements. An aseptic surgical technique was followed. Antimicrobial prophylaxis included amoxicillin 500 mg thrice daily for 5 days, starting 1 h before surgery and postsurgery analgesic treatment was ibuprofen 400 mg twice daily for 3 days. All implants were placed by one operator, patients were treated under local anesthesia, surgical site was examined and implant length and diameter was selected for each patient based on individual clinical needs. After crestal incision on a healed site, and raising mucoperiosteal flap, an initial pilot drill was passed through the surgical stent to the depth corresponding to the length of the implant chosen. Next intermediate drills of the diameter and length of the implant were used to expand the osteotomy. Then paralleling pins were used to verify that the desired angulation of the implant is correct. The implant with its attached cover screw was placed into the prepared site with gentle digital pressure until resistance is met and seated into final position. The procedure was completed by repositioning and suturing the surgical flap. Stability of implant was measured by osstell. Sutures were removed after 7 days and kept unloaded for 3 weeks. At a 3rd week, at this time, again another reading of the ISQ was recorded with the help of a resonance frequency analyzer - osstell - ISQ. Then impression was made and the prosthesis was delivered. All implants were restored with porcelain fused to metal crowns with porcelain occlusals and crowns were retained with zinc polycarboxylate cement. Soft tissue and bone level evaluation was done using clinical and radiographic parameters and statistical analysis was made [Figures 1–6].

Figure 1

Alpha bioimplant kit

Figure 6

ISQ reading by osstell taken before giving prosthetic part

Alpha bioimplant

Osteotomy

Implant in place

Gingival former placed at the time of implant placement

Clinical parameters assessed: After the prosthesis, the periimplant soft tissue status was assessed at 3 weeks, 3 months, 6 months, and 9 months. All the patients were subjected to evaluation under following parameters.

Sulcus bleeding index (sBI) by Mombelli (1987)[4]

Probing pocket depth (PD) was assessed at 4 sites around implant (mesial, distal, buccal, and lingual)[5]

Papilla index (PI) by Jemt (1997).[6]

Radiographic parameters assessed

Radiographs were taken using the long cone paralleling technique and assessed at the baseline, 3 weeks, 3 months, 6 months, and 9 months.

All the radiographs taken at different intervals were subjected to assess bony changes around each implant. Crestal bone level (CBL), measured as the distance between the implant abutment junction(IAJ) and the most coronal point of the bone calculated using grid X-ray(IOPA) in distal and mesial aspect of each implant. This parameter was evaluated at baseline, 3 weeks (loading), 3 months, 6 months, and 9 months. Standardized intraoral periapical radiographs of the Implant sites were taken using a paralleling technique with a customized film holder. The intraoral periapical radiograph along with grid was held in position by the means of a holder attached to the paralleling device and the suitable exposure was made. The occlusal platform allowed an occlusal registration to be made; thus, preserving source to object and object to film distances. The same holders were used throughout and the exposure time and film developing were also standardized. These radiographs were then utilized to assess any changes in CBL.[78]

RESULTS

The software used for the statistical analysis was Statistical Package for Social Sciences (SPSS) version 16.0 (IBM, USA). The values were represented in number (n), percentage (%), and mean (υ). The analysis of variance (ANOVA) test for comparison of the difference between more than 2 mean values. The P value was taken significant when < 0.05 (P < 0.05) and confidence interval of 95% was taken.

Radiographic results, mean value for crestal bone loss (mesial) at baseline 0.25 ± 0.11, at 3 weeks 0.31 ± 0.08, at 3 months 0.67 ± 0.13, at 6 months 0.85 ± 0.09, and at 9 months 0.88 ± 0.12. Repeated ANOVA was done for comparison of mean crestal bone loss at different times. There was a significant difference among the means of crestal bone loss at different points of time with P = 0.000 [Figure 7 and Table 1]. Mean value for crestal bone loss (distal) at baseline 0.25 ± 0.12, at 3 weeks 0.31 ± 0.09, at 3 months 0.71 ± 0.10, at 6 months 0.76 ± 0.09, and at 9 months 0.75 ± 0.11 which was statistically very highly significant (0.000) [Figure 8 and Table 2].

Figure 7

Mean crestal bone loss (mesial)

Table 1

Post-hoc tests - Bonferroni multiple comparisons

Figure 8

Mean crestal bone loss (distal)

Table 2

Post-hoc tests - Bonferroni multiple comparisons

Clinical parameters

Probing PD, mean value at 3 weeks 1.20 ± 0.83, 3 months 1.60 ± 1.1, at 6 months 1.40 ± 1.14, and at 9 months 1.20 ± 1.0 [Figure 9]. Repeated ANOVA was done for comparison of mean probing PD at different times. There was a nonsignificant difference among the means of probing PD at different points of time with P = 0.5.

Figure 9

Mean pocket probing depth

sBI, mean value for sBI at 3 weeks 0.00 ± 0.00, 3 months 0.3 ± 0.11, at 6 months 0.09 ± 0.25, and at 9 months 0.08 ± 0.24 [Table 3]. Repeated ANOVA was done for comparison of mean sBI at different times. There was a nonsignificant difference among the means of sBI at different points of time with P = 0.3.

Table 3

Mean and SD of sBI at different time intervals

Papilla-index (mesial)

Pearson Chi-square was done for the comparison of the percentage of PI at different times [Table 4]. There was a significant difference among the percentage of PI at different points of time with P = 0.000 with Score 1 at 3 weeks in 75% of cases, Score 2 at 3 months in 60% of cases, and Score 3 at 6 and 9 months in 90% of cases.

Table 4

PI (mesial) at different time intervals expressed in percentage

Papilla-index (distal)

Pearson Chi-square was done for the comparison of percentage of PI at different times [Table 5], there was a significant difference among the percentage of PI at different points of time with P = 0.000 with Score 1 at 3 weeks in 65% of cases, Score 2 at 3 months in 55% of cases, and Score 3 at 6 and 9 months in 90% of cases.

Table 5

PI (distal) at different time intervals expressed in percentage

DISCUSSION

Historically, the Branemark protocol favored a prolonged healing period, to allow stabilization of the bone interface prior to the clinical function but number of authors have reported that early or immediate loaded implants show a greater percentage of bone-to-implant contact and more mature cortical bone than delayed loaded controls. The factors that relate to implant stability include bone quality, quantity, surgical technique, and implant design, which may influence the timing of loading for each individual situation. Despite the high success rates, complications and failures still occur. Implant success is reported to depend on both biologic tissue (soft tissues and bone) response and mechanical components strength (implant components and superstructure). The soft tissue is more susceptible to invasion by bacteria, whereas bone may be more susceptible to loading, both having been implicated in bone loss around implants.[2] Thus, In this study comparisons of hard and soft tissues changes around early loaded implants in single stage delayed placement of implants for the follow-up period of 9 months was done. Most of the studies describe only short-term results and the need for longer studies, with a follow-up of at least 5 years has been expressed by several authors, the 5 years results of the study showed that early loading of implants with a fluoride treated grit-blasted surface is possible in the posterior mandible with a high degree of predictability with respect to survival rate, marginal bone level maintenance and periimplant soft tissue status.[3] The crestal bone loss during the follow-up period in this study was well controlled, showing mean value ranging from baseline 0.25 ± 0.11 to 0.31 ± 0.08 at 3 weeks, to 0.67 ± 0.13 at 3 months, to 0.85 ± 0.09 at 6 months, and to 0.88 ± 0.12 at 9 months which is comparable to one of the studies, in which the mean crestal bone loss at 6 months was found to be 1.2 mm (standard deviation [SD]: 0.98) and 1.8 mm (SD: 1.02) on mesial and distal surface of implant, respectively. Turkyilmaz[1] reported the average marginal bone loss of 0.7 mm for one stage implant at 1-year recall. Schwartz-Arad et al.[9] reported statistically significant (P < 0.05) bone loss around the implants placed in the maxilla, as compared to those in mandible in edentulous patients. Higher mean marginal bone loss on mesial and distal surfaces could be due to the fact that all the implants were placed in the maxillary anterior region. Bone loss occurs mostly in 1st year after surgery, authors showed that a large percentage of initial bone loss occurred during the 1st month in one stage implant. After the 1st year of function, an immediate restoration did not seem to cause a greater average amount of bone loss.

In the present study, there was no significant bone loss when compared between baseline and 3 weeks (at the time of loading) but when compared at 3 months the mean value was significant.

This difference might have resulted from patient-related factors such as quality of mandibular bone, excessive chewing forces, and patient oral hygiene status. Initial crestal bone loss (between baseline and early healing) may also have occurred when implants had to be placed in an uneven bone surface and when placement of the rough/smooth implant border was not located with the lowest bone level of the bone crest. Furthermore, the physiologic response to the microgap/interface at the connection to the superstructure, it has been demonstrated that bacteria are present in such microgaps (interfaces), may form a reservoir and that the host reacts with an inflammatory response which may have resulted in the tissue remodeling.[1] Increased periodontal PD (PPD) was reported to be an important indicator, suggesting a high risk of infection developing in the implant mucosa by Becker, et al.[10] A significant increase in PPD was not observed with time in the present study, from 1.20 ± 0.83 at 3 weeks, to 1.60 ± 11.10 at 3 months, to 1.40 ± 1.14 at 6 months, and to 1.20 ± 1.06 at 9 months indicating that the implant mucosa was kept in healthy condition from the beginning of the study. Bleeding from the junctional epithelium of the implant has been considered an early symptom of periimplantitis. For implants, Jepsen et al.[11] reported that BOP had a high negative predictive value for monitoring periimplant health, and Luterbacher et al.[12] concluded that BOP has statistically higher diagnostic values for implants than for teeth. It was reported that higher scores of BOP were recorded from the healthy implant sites compared with the healthy natural dentition in the dog by Ericsson and Lindhe.[13] In the present study, despite the prescribed postoperative use of chlorhexidine mouth rinse in nonperiodontitis patients with good overall hygiene, 87% of implant sites show healthy gingiva. sBI during the follow-up in this study was well-controlled mean value from 0.00 at 3 weeks, to 0.03 ± 0.11 at 3 months, to 0.09 ± 0.25 at 6 months, and to 0.08 ± 0.24 at 9 months. In present study, significant increase in PI (mesial) during the follow-up period in this study was observed with Score 1 at 3 weeks, to Score 2 at 3 months, and to Score 3 at 6 and 9 months. A significant increase in PI (distal) during the follow-up period in this study was observed with Score 1 at 3 weeks, to Score 2 at 3 months, and to Score 3 at 6 and 9 months. Choquet et al.[14] reported the clinical and radiographic evaluation of the papilla level adjacent to the single tooth dental implant in the vertical component only when the Jemt PI is scored according to the actual distance between the crestal bone and the contact point it is apparent that the papillae can demonstrate a wide range of thicknesses within the scoring categories, e.g. Score 3, a complete fill of the interproximal triangle was apparent for papillae ranging between 2.3 mm and 8.5 mm. The vertical distance between the crest of bone on the natural tooth and the contact point as it relates to the Jemt PI score.[9]

CONCLUSION

The dental implants showed <1 mm of crestal bone loss at 9 months follow-up than the commonly found in delayed loaded implants. This is probably the result of stable bone attachment and epithelial attachment to the implant collar, resulting in a stable soft tissue seal that protected the crestal bone.

These data demonstrate that, in general, the clinically significant marginal bone loss occurred between the time of implant placement and 3 months. The periimplant soft tissue maturity was maintained throughout the study. Despite some limitations such as short follow-up period and obvious clinical challenges, single stage Implant, loaded early represents a desirable and justified treatment options.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.