TITLE: The efficacy of flapless implant surgery on soft-tissue profile comparing immediate loading implants to delayed loading implants: A comparative clinical study

  ABSTRACT.AIMS AND OBJECTIVES:
To assess the efficacy of flapless implant surgery on soft-tissue profile and to compare the clinical outcomes of flapless implant therapy on immediate loading (IL) implants to delayed loading (DL) implants.

ABSTRACT.MATERIALS AND METHODS:
The study sample consisted of 20 patients who were partially edentulous in the anterior maxillary region. They were divided into two groups. In group I (IL) 10 implants were placed and immediately provisionalized and restored with a metal ceramic crown on the 14th day. In group II (DL) 10 implants were placed and loaded after 4 months. Single-piece implants were used for the IL group and two-piece implants were used for the DL group. All soft tissue parameters i.e., modified plaque index (mPI), modified bleeding index (mBI), papillary index (PPI), marginal level of soft tissue (ML) and width of keratinized mucosa (WKM) were recorded at baseline, Day 60, Day 120 and Day 180.

ABSTRACT.RESULTS:
The success rate in group I was found to be 80%, which was lower than the success rate in group II which was found to be 90%. On comparison, there is no statistically significant difference in success rate between the two study groups. There was no statistically significant difference between the groups over time in parameters like mPI, mBI, ML and WKM. The mean PPI score in group II showed a significant increase from when compared to group I.

ABSTRACT.CONCLUSION:
The results of this study indicated that flapless implant surgery using either immediately loading implants or DL implants, demonstrate enhancement of implant esthetics.

BODY.INTRODUCTION:
Dental implants are devices, usually alloplastic in nature that are surgically inserted into or onto the jawbone, which support a single prosthetic tooth and serve either as abutments or as cosmetic replacements for missing teeth. Dental implant therapy has been demonstrated to be a highly successful and predictable treatment modality for replacement of missing teeth.  Flapless or minimally invasive surgery offers clinicians the possibility of placing implants in less time, without extensive flaps, and with perceived less bleeding and postoperative discomfort for the patient. Medicine has implemented minimally invasive procedures for prostate, abdominal, orthopedic and other types of surgery. Minimally invasive surgery reduces bleeding and discomfort.[1]  The favorable outcomes using the immediate loaded (IL) implants enabled the clinicians to broaden the arena of implant dentistry enhancing esthetic and functional outcomes in addition to osseointegration. The accelerated treatment time and less surgical intervention via IL implants and one-stage surgical approach can significantly enhance patient comfort, satisfaction and acceptance. Francetti et al. demonstrated high bone-to-implant contacts ranging from 78 to 85% using the IL implants in edentulous mandibles.[2] Chiapasco et al. compared the effect of IL with DL of implants and concluded that no significant difference was present between the two groups, suggesting that IL is not detrimental for osseointegration.[3]  With the advancement of dental implant therapeutics, the current trend is more geared toward enhancing patient esthetics and patient comfort and satisfaction. Van der Zee reported postsurgical tissue loss following flap reflection in the two-stage procedure of implant placement, implying that flap surgery for implant placement may negatively influence implant esthetic outcomes especially in the maxillary anterior region.[4] William et al. suggested that implants placed without flap reflection remain stable and exhibit clinically relevant osseointegration similar to implants placed with flapped procedures.[1]  The purpose of this study is to examine the soft-tissue profile changes of single-tooth implants in the premaxillary region after flapless implant surgery comparing IL implants to DL implants.

BODY.MATERIALS AND METHODS:
The present clinical study was carried out in the Department of Periodontology and Implantology, Meenakshi Ammal Dental College and Hospital, Chennai, after obtaining approval from the ethical committee. The study sample consisted of 20 patients with missing teeth in the premaxillary region. They were randomly selected and divided into two groups (group I and group II) of 10 each. In group I, single-piece implants and in group II two-piece implants were placed using flapless implant surgery.  The criterion for inclusion was partially edentulous patients with missing teeth in the premaxillary region and patients with natural teeth present mesial and distal to the edentulous spaces. Patients with complicated medical history such as uncontrolled diabetes, bleeding disorders, osteoporosis, radiation therapy and smoking were excluded from the study. Also patients with untreated chronic periodontitis and patients with history of bruxism were omitted from the study.

BODY.STUDY DESIGN.PRESURGICAL PROCEDURE:
Selection of patients was followed by full-mouth scaling, root planing and oral hygiene instructions. Informed consent was obtained after explaining the proposed nature of the study. Orthopantomograms and intraoral periapical radiographs (IOPA) were taken to assess the quality and quantity of bone around the proposed implant sites. Casts and surgical stents were fabricated for all the patients. All clinical parameters i.e., modified plaque index (mPI), modified bleeding index (mBI), papillary index (PPI), marginal level of soft tissues (ML) and width of keratinized mucosa (WKM) were recorded on Day 0.  A single-piece and two-piece implant system (LifeCare Devices Private Limited) was used for this study. These implants are well-suited for IL protocol and DL protocol. They are available in diameters ranging from 2.8 to 5.0 mm and from lengths 10 to 16 mm.

BODY.STUDY DESIGN.SURGICAL PROCEDURE:
The surgical field was prepared using betadine solution and the areas were anesthetized using 2% xylocaine hydrochloride with adrenaline (1:200000). In the recipient implant sites, guided by the surgical stent, implants were placed using flapless technique. A small round bur was used to enter the osteotomy site. Pilot drill was then used to establish the depth and align the long-axis of the implant recipient site. Then a series of drills were used sequentially, according to the implant site selected to widen the osteotomy site. Implants were then placed into the site. Single-piece implants were used for IL and two-piece implants were used for DL group.

BODY.STUDY DESIGN.POSTSURGICAL PROCEDURE.GROUP I -IL:
IOPA were taken. For the site to be IL (group I) an acrylic provisional restoration was given. The patient received amoxicillin 500mg, three times a day for 5 days and ibuprofen 400 mg thrice a day for three days. In this group metaloceramic restorations were given on the 14th day. On the Day 60, Day 120 and Day 180 all clinical parameters were checked and IOPAs were taken [Figure 1c–g].  Figure 1Group I (IL) - (a)Pre-operative; (b) Immediate post-operative; (c) Provisional prosthesis placed; (d) Final prosthesis placed on day 14; (e) Final prosthesis on day 60; (f) Final prosthesis on day 120 ;(g) Final prosthesis on day 180

BODY.STUDY DESIGN.POSTSURGICAL PROCEDURE.GROUP II -DL:
IOPAs were taken. For the DL all the same procedures were carried out as group I and appropriate instructions were given, except for temporization of the implant site. Instead of a temporary crown, a healing cap was placed over the implant and permanent crowns were delivered 4 months after implantation. All clinical parameters were recorded and IOPAs were taken on the Day 60, Day 120 and Day 180 [Figure 2d–h).  Figure 2Group II (DL) - (a) Pre-operative; (b) Immediate post-operative; (c) Healing cap placed; (d) Second stage surgery; (e) Gingival former placed; (f) Abutment placed; (g) Final prosthesis on day 120; (h) Final prosthesis on day 180

BODY.STUDY DESIGN.CLINICAL PARAMETERS.MPI[:
0: No plaque  1: Plaque detected by probe  2: Plaque visible to naked eye  3: Abundant plaque

BODY.STUDY DESIGN.CLINICAL PARAMETERS.MBI[:
0: No bleeding  1: Isolated bleeding spots  2: Confluent blood line  3: Heavy bleeding

BODY.STUDY DESIGN.CLINICAL PARAMETERS.PPI[:
Measurements were made from the reference line connecting the highest gingival curvatures of implant crown restoration and adjacent tooth on buccal side.  0: No papilla  1: Less than half  2: More than half but not complete fill  3: Complete fill  4: Overfill

BODY.STUDY DESIGN.CLINICAL PARAMETERS.ML[:
It was measured from the reference line drawn fromthe free gingival margins of adjacent teeth. The tissue levelapical to the reference line was recorded as positive,whereas a negative value was given when the tissue levelwas coronal to the reference line (Figure 3].  Figure 3Measurement of marginal level (ML) of soft tissue

BODY.STUDY DESIGN.CLINICAL PARAMETERS.WKM:
The width of the peri-implant keratinized tissue calculated by painting the gingiva with Schiller's potassium iodide at the implant site [Figure 4a–c].  Figure 4Measurement of Width of Keratinised Mucosa (WKM)  0: > 2 mm  1: 1 mm  2: 0 mm

BODY.STUDY DESIGN.STATISTICAL ANALYSIS:
Mean and standard deviation were estimated from the sample for each study group. Mann-Whitney's U-test was used to calculate intergroup variations. Wilcoxon signed rank test was used to calculate intragroup variations Single piece implants were used for IL [Figure 1a–b] and two piece implants were used for DL group [Figure 2a–c].

BODY.RESULTS:
The sample for the study included 20 subjects who were randomly divided into two groups (groups I and II). In group I, single-piece and in group II two-piece implants were placed using flapless implant surgery. Group I (IL) consistedof 10 patients where implants were placed and immediately loaded. Group II (DL) consisted of 10 patients where the implants were placed and loaded after 4 months. The success rate in group I was found to be 80%, which was lower than the success rate in group II which was found to be 90%. On comparison, there was no statistically significant difference in success rate between the two study groups [Table 1].   Table 1 Comparison of clinical parameters between groups   It was also inferred that there is no significant difference in mean mPI, mean mBI, WKM and ML of soft tissue between group I and group II at different time point's viz., at Day 0, Day 60, Day 120 and Day 180 [Tables 1 and 2].  Table 2 Comparison of clinical parameters (ML)   On comparison the difference in mean PPI score between the groups on Day 60 was statistically significant and the mean change in PPI score from Day 60 to Day 180 between the groups was statistically significant [Table 1].

BODY.DISCUSSION:
Flapless implant surgery has been suggested as one possible treatment option for enhancement of implant esthetics in the anterior maxilla. Flapless implant surgery requires penetration of the alveolar mucosa and bone without the reflection of mucoperiosteal flaps.[8] Flapless or minimally invasive implant surgery offers the clinician, the possibility of placing implants in less time, without extensive flaps, less bleeding and less patient discomfort.[4] There have been reports of postsurgical tissue loss from flap reflection, implying that flap reflection may have a negative influence on soft tissue profile, especially in the anterior maxilla. Concerns in flapless implant surgery are that tissues might be forced into the osteotomy site, potentially compromising osseointegration, but conclusions of a histological study showed that flapless implant placement is as biologically successful as placement of implants following mucoperiosteal flap reflection and does not produce any deleterious effects.[1] However, the clinician should keep in mind that patients treated with flapless implant surgical approach must be carefully planned and have sufficient bone volume for implant placement.  Earlier studies reported that implants must be in a load-free condition for some months because micromotion at the bone-implant interface produced a fibrous repair.[9] However, now it is believed that IL of dental implants will be of clinical interest and of great benefit to the patient. Immediate loading of a dental implant not only includes a non-submerged; one-stage surgery but also actually loads the implant with a provisional restoration at the same time or shortly thereafter.[3] Earlier reports with IL implants were unpredictable; however, recent studies have showed encouraging results.  In our study in group I, two of the 10 IL implants failed to osseointegrate leading to an 80% success rate. Previous studies also reported a wide range of failure rates in IL single tooth implants ranging from 0 to 19%.[10] The failure in the IL implants can be attributed to poor quality of bone, which could not be assessed as flapless technique was used and compromised healing phase. Another reason for failure in the IL group maybe due to excessive occlusal forces applied by the patient, by not complying with the postoperative instructions after loading of the implant. In an earlier study with no implant failure permanent crowns were delivered 6 months after use of temporary crown, unlike this study where permanent restorations were delivered on the 14th day.[11] In group II, one of the 10 implants placed using DL protocol failed, leading to 90% survival rate. The failure to osseointegrate might be due to inability to assess bone quality as flapless technique was used or improper angulations during placement of the implant using flapless technique. This is in contrast with most of the studies which show high success rate with DL protocol.  The mPI and mBI were recorded using the index described by Mombelli A et al.[5] When the mean score between the groups were compared at different time points, there was no statistically significant difference. This is in accordance with other studies by Buser et al.[12] and Oh et al.[7] In general, the patients performed good home care and maintained good oral hygiene. Patients were informed about the subsequent consequences of plaque accumulation around implants and they were motivated to maintain oral hygiene by demonstrating oral hygiene techniques at every visit.  The PPI was evaluated using the index described by Jemt et al.[6] Generally, the cause for papilla reduction after implant placement could be due to elevation of adjacent papilla during implant surgery.[4] A clinical study by Gomez Roman G showed that the elevation of adjacent papilla caused more bone loss compared to a technique that does not include the papilla.[13] This was minimized by using a flapless approach in our study. The interdental papilla height increased 2 months after IL implant therapy, which might have resulted from tissue remodeling after surgery and reformation of biological width. This is similar to a previous randomized controlled clinical trial by Oh et al.[7] In the DL group, papilla growth was observed after 4 months. This can be attributed to the fact that the permanent restorations for DL group were delivered 4 months after implant surgery. This corresponds to an 18-month follow-up study by Jemt et al.[6]  The MLs were measured from the reference line drawn from the free gingival margin of adjacent teeth. No significant changes occurred in ML from baseline to 6 months. These results are similar to the conclusions of a study by Oh et al.[7]  The WKM was measured by painting the mucosa with Schiller's potassium iodide which stains the keratinized tissue pale yellow. When the mean width of keratinized mucosa between group I and group II were compared at different time points, there was no statistically significant difference. This is in accordance with other studies by Buser et al.[12] and Oh et al.[7] which showed similar results. The level of the facial mucosa is an important soft tissue parameter for the esthetic outcome, and it has gained increasing attention in recent years. To achieve a correct mucosa level on the facial aspect, two prerequisites need to be fulfilled according to Kan et al. which are that the implant has to be correctly positioned in the orofacial and corono-apical directions and the mucosa must be supported by a facial bone wall of sufficient height and thickness, because the peri-implant mucosa has a rather constant dimension of 3.5-4.5 mm on the facial aspect.[14]  With the rapid advancement of dental implant therapeutics, the current trend is enhancing patient comfort and esthetics.[15] Therefore, flapless implant therapy can be used to preserve soft tissue profile and increase patient comfort and satisfaction. However, flapless implant surgery has its limitations such as inability for the clinician to directly assess bone quality during implant placement, which may lead to implant failure.  The present study has several limitations. The study did not follow a split-mouth design which would have ensured minimizing the effects of interpatient variability. Other limitations include small sample size, short-term follow-up and failures in the IL group. More studies with larger sample size and longer follow-up periods are required to understand the effect of flapless implant surgery on soft-tissue profile.

BODY.CONCLUSIONS:
The results of this study indicate that flapless implant surgery using either IL or DL implants, demonstrate enhancement of implant esthetics. Long-term clinical trials with high level of evidence, adequate sample size and comparison group (i.e., implant surgery with flap surgery) are required to verify the conclusions of this study.

Question: Compared to Delayed loading implants (group II) what was the result of Immediate loading implants (group I) on Rate of success?
Evidence: The success rate in group I was found to be 80%, which was lower than the success rate in group II which was found to be 90%. On comparison, there was no statistically significant difference in success rate between the two study groups
Answer: no significant difference