Indian Journal of Dental Research

: 2015  |  Volume : 26  |  Issue : 4  |  Page : 372--377

Flapless versus open flap techniques of implant placement: A 15-month follow-up study

Bhavita Wadhwa1, Veena Jain1, Ongkila Bhutia2, Ashu Seth Bhalla3, Gunjan Pruthi4,  
1 Centre for Dental Education and Research, All Institute of Medical Sciences, New Delhi, India
2 Department of Oral and Maxillofacial Surgery, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi, India
3 Department of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India
4 Department of Prosthodontics, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi, India

Correspondence Address:
Gunjan Pruthi
Department of Prosthodontics, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi


Aim: To evaluate and compare the effect of flapless and “open flap” techniques of implant placement on crestal bone height (CBH) around implants. Materials and Methods: This prospective study comprised of 32 implants placed in 16 subjects with a bilateral missing mandibular first molar. In each subject, one implant was placed with “flapless” and other using “open flap” technique. Radiographic assessment of CBH was carried out using standardized intraoral periapical radiograph of the site at baseline, 3 months, 9 months and 15 months after implant placement. Statistical Analysis: Data were analyzed using STATA 11.0 statistical software. To determine the changes in CBH from baseline, at 3-, 9-, and 15-month, repeated measures analysis of variance followed by post-hoc Bonferroni was used for each of the two techniques for mesial and distal aspects separately. For both techniques, changes in CBH from baseline to 15 months were compared using an independent t-test with a confidence interval of 95%. Results: For “flapless” technique, there was no statistically significant (P > 0.05) reduction of CBH in initial 9 months but was significant for the 9–15 months period while for “open flap” technique, statistically significant (P < 0.05) reduction was observed up to 15 months. Comparison of both techniques showed significantly lesser reduction with “flapless” than “open flap” technique. The overall average crestal bone loss was 0.046 ± 0.008 mm on mesial aspect, 0.043 ± 0.012 mm on distal aspect with “flapless” technique and 1.48 ± 0.085 mm on mesial aspect, 1.42 ± 0.077 on distal aspect “open flap” technique. Conclusions: Both techniques showed a reduction in CBH with time but the flapless technique showed a lesser reduction. Therefore, the flapless technique can be considered as a better treatment approach for placement of implants, especially where adequate width and height of available bone are present.

How to cite this article:
Wadhwa B, Jain V, Bhutia O, Bhalla AS, Pruthi G. Flapless versus open flap techniques of implant placement: A 15-month follow-up study.Indian J Dent Res 2015;26:372-377

How to cite this URL:
Wadhwa B, Jain V, Bhutia O, Bhalla AS, Pruthi G. Flapless versus open flap techniques of implant placement: A 15-month follow-up study. Indian J Dent Res [serial online] 2015 [cited 2021 Jan 16 ];26:372-377
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Full Text

Dental implants generally present with multiple therapeutic possibilities, high predictability of success and are considered to be a reliable approach to replace missing teeth regardless of the disease or injury of the stomatognathic system.[1] In simple words, an implant is said to be successful if it osseointegrates well with the host bone and is able to sustain occlusal stress during the function.

Traditionally, access for implant placement has been by a flap approach. Studies have demonstrated that flap reflection often results in bone resorption around the natural teeth.[2],[3] Postsurgical tissue loss from flap reflection has also been reported in the literature.[4]

Recent studies have reported minimized access for implant placement by flapless approach.[5] The flapless technique has been documented to be a simpler procedure as compared to “open flap” technique and is associated with several advantages such as preservation of soft tissue architecture, improved patient comfort and satisfaction.[6],[7],[8],[9],[10] Furthermore, the intact periosteum maintains a better blood supply, thus reducing the likelihood of early bone resorption.[11]

However, flapless implant surgery has some limitations which include greater skill required on the part of surgeon to visualize anatomic landmarks and vital structures; the potential for thermal damage secondary to reduced access for external irrigation during osteotomy preparation; the increased risk of malposed angle or over or under drilling of the osteotomy site; a decreased ability to contour osseous topography when needed to facilitate restorative procedures and to optimize soft tissue contours and; most important the inability to manipulate soft tissues to ensure circumferential adaptation of adequate dimensions of keratinized gingival tissue around emerging implants.[6]

The choice of surgical procedure according to the literature depends upon its success rate, simplicity and experience of the operator while for the patient; comfort is an important criterion. Limited controlled data are available to evaluate the crestal bone height (CBH) after flapless implant surgery. In addition, most crestal bone loss occurs in the early phase after implant placement.[12],[13],[14] The purpose of this study was to evaluate and compare the changes in the CBH around implants placed with “flapless” and “open flap” techniques, for a period of 15 months.

 Materials and Methods

Ethical clearance was obtained from the Ethics Committee (Ref No.: IESC/T-146/01.04.2011) of the Institute, before the start of this prospective study.

A total of 16 subjects within the age group of 25–40 years, irrespective of gender were selected according to the inclusion and exclusion criteria. Inclusion criteria were subjects with bilaterally missing mandibular first molars, having D1 (>1250 HU) to D3 type (350–850 HU) of bone density, total bone width of minimum 5 mm and bone height of 10–13 mm, good periodontal status and presence of all posterior teeth in maxillary arch. Subjects having systemic diseases such as uncontrolled diabetes mellitus, blood dyscrasias, neuromuscular disorders or having history of any parafunctional habits, radiotherapy in head and neck region, myocardial infarction within 6 months or immune compromised patients, smokers, and pregnant females were not included in the study.

All the subjects were explained about the study and both verbal and written informed consents were obtained. After recording the patient's medical and personal history, the complete dental examination was performed. The initial radiographic assessment was done using intraoral periapical (IOPA) radiograph and orthopantomograph. DentaScan was used to determine the bone height, width and density and accordingly, the position and orientation of implants in relation to adjacent anatomical structures were planned [Figure 1]a and [Figure 1]b.{Figure 1}

In each subject, one implant was placed with “flapless” technique and other using “with flap” technique so as to maintain uniformity in the study. Statistical randomization was done to select the proposed site for flapless and with flap technique. Tapered threaded implants, (Vision ™ Hi-Tec implants, Lifecare Devices Private Limited, New Delhi, India) were placed in the edentulous site using standard protocol and aseptic technique. Implant placement was carried out by the single senior experienced operator to eliminate operator bias.

A self-curing clear acrylic resin stent was prepared for bone mapping, and seven holes were prepared in the middle of the first molar region, 2 mm apart from each other. Three holes were prepared on the buccal and lingual slopes of the ridge and one on the crest of the ridge. Bone mapping was done after spraying of local anesthetic, according to the holes prepared on the stent using a No. 20, sterile, endodontic file with a rubber stop. The endodontic file was introduced perpendicular to the soft tissue until it was stopped by the resistance of the underlying bone. The readings were measured on a scale. The cast was sectioned in the middle of first molar region using a saw, and the values obtained by bone mapping were transferred on to the sectioned part of the cast using the resin stent and the same endodontic file. Markings on the cast were connected to get the morphology of the bone. According to the bone morphology, the implant diameter was decided, and the cast was sectioned at the prospective implant site. Implant analogue was placed in the drilled site, and the impression post was screwed on it. Parallel block out was done on the impression post to obtain a uniform diameter of 2 mm. Sectioned cast was reassembled, and 3 mm thick bio-acryl sheet was adapted over the cast using Biostar machine [Figure 2]a and [Figure 2]b. Finally, this surgical stent was disinfected before using it for the surgical procedure.[15]{Figure 2}

A single dose of antibiotic (amoxicillin [500 mg] + clavulanate potassium [125 mg]) was given 1 h before surgery. Lignocaine with adrenaline (1:100,000 concentration) was used to anaesthetize the surgical site.

In case of “flapless” technique, osteotomy was initiated by using a pilot drill of 2 mm through surgical template to drill the bone followed by the use of tissue punch guide according to implant size and tissue punch to punch out the soft tissue. Subsequent drilling was done to prepare the site according to the selected implant size. After the complete embedding of the implant into the bone, secondary healing cap was tightened over the implant to allow tissue healing. IOPA radiograph was taken after the procedure to confirm complete insertion of the implant [Figure 3]. Postoperative antibiotics and analgesics were prescribed to the patient for 5 days. Another implant was placed on the opposite edentulous site using “open flap” technique after 2 days of first implant placement, under the same antibiotic cover.{Figure 3}

For “open flap” technique, a sub-crestal incision was given to reflect the mucoperiosteal flap. The osteotomy was initiated using a pilot drill of 2 mm through the surgical template followed by sequential drilling to prepare the site according to the selected implant size. Copious irrigation with saline was done during the surgical procedure. The implant was inserted with the help of insertion tool and a torque wrench. Minimum of 35–40 N-cm of torque was achieved which ensured the primary stability of the implant. After complete insertion of the implant into the bone, the primary cover screw was tightened to protect central screw hole and suturing was done with 3–0 black silk suture.

Subjects were prescribed analgesics, antibiotics, and saline gargles for 5 days. Subjects were instructed to maintain oral hygiene, to take soft diet for 24 h and were recalled after 7 days for removal of the sutures from the site where the open surgical procedure was done. Final impression was made after 3 months using indirect technique followed by fabrication and cementation of implant supported porcelain fused to metal crowns on both sides [Figure 4].{Figure 4}

IOPA radiographs of the sites with parallel cone technique (long cone) using re-positionable film holders (as it eliminates the distortion and limits magnification to <10%) was taken immediately, at 3-, 9-and 15-month of implant placement [Figure 5] and [Figure 6]. Radiographs were scanned, digitized in JPG format, and stored on a personal computer. Periimplant marginal bone levels were measured at various intervals of time between the reference point that is, apex of the implant and marginal bone level at mesial and distal sides of the implant using XVa3 (Unicorn Dental Products) software. These measurements were done after calibrating the software to avoid any error in the values. All measurements were done by two examiners who were blinded to the methods used in the study. Measurements were repeated in case of any mismatch. This gave us the measurement of the crestal bone loss around an implant with time.{Figure 5}{Figure 6}

To determine the changes in crestal bone level from baseline, at 3 months, at 9 months, at 15 months, repeated measures analysis of variance followed by post-hoc Bonferroni was used for each of the two techniques for mesial and distal aspects separately. For both the techniques, changes in crestal bone levels from baseline to 15 months were compared using an independent t-test with a confidence interval of 95%.

STATA 11.0 statistical software was used for data analysis. P < 0.05 was considered as statistically significant.


The mean crestal bone levels around implants was evaluated and compared at four different time points that is, immediately, 3-, 9- and 15-month after implant placement on both the proximal aspects (mesial and distal) for both techniques separately. No drop outs were registered during follow-up of the study.

In both techniques, reduction in CBH was present on both proximal aspects [Table 1]. Flapless technique showed statistically nonsignificant reduction in initial 9 months (P > 0.05) on both proximal aspects while significant reduction was observed (P < 0.05) from 9 to 15 months. On the other hand, statistically significant reduction of CBH was observed at different time intervals on both proximal aspects of implants placed “open flap” technique (P < 0.05) [Table 2].{Table 1}{Table 2}

Comparison of both techniques showed that the mean difference of crestal bone levels at different time intervals around both the proximal aspects of implants placed with flapless technique was significantly lower than “open flap” technique (P < 0.05). The overall average crestal bone resorption was 0.046 ± 0.008 on mesial aspect, 0.043 ± 0.012 on distal aspect with flapless technique and 1.48 ± 0.085 on mesial aspect, 1.42 ± 0.077 on distal aspect using with “open flap” technique [Table 3].{Table 3}


Long-term success and failure of various techniques depend upon a traumatic surgical procedure, primary implant stability and finally amount and quality of bone surrounding the implant. This study showed 100% success rate at 15 months. According to Albrektsson et al.'s success criteria,[14] the average marginal bone loss should be <1.5 mm during the first year of functional use of the implant. Findings of the present study showed that none of the implants with both the techniques had a bone loss >1.5 mm after the first year of loading.

The results of the present study showed that with “flapless” technique, change in CBH on both the proximal aspects was nonsignificant during initial 9 months while in later stages significant changes were observed. The overall change in mesial aspect was 0.046 mm and on distal aspect was 0.043 mm. Sunitha and Sapthagiri [16] found that flapless surgery resulted in the nonsignificant crestal bone loss of (0.03–0.09 mm) on both proximal aspects during the healing period and after loading. Jeong et al.[17] observed mean marginal bone loss ranging from 0.0 to 1.1 mm with flapless technique over a period of 1-year. Becker et al.[18] also noted nonsignificant bone loss around implants placed with flapless technique until 2 years. A MEDLINE search on studies published from 1966 to 2008 reported a mean radiographic bone loss ranging from 0.7 to 2.6 mm after implant placement with flapless technique.[19]

Variations between initial and later stages of study (0–9 months, 9–15 months) may be due to the intact periosteum that maintained a better blood supply, thus reducing the likelihood of early bone resorption while in later stages normal physiological bone resorption was seen.[11],[20]

Flap elevation permits easy access to the operator and visibility of the planned site. It is considered advantageous when aesthetics of the soft tissue is critical since it can be manipulated to a desirable position.[5] Tissue augmentations can be predictably achieved at the time of implant placement. However, Van der Zee et al.[4] studied the effect of flap reflection on gingiva and bone following guided bone regeneration and found that there was statistically significant gingival recession and bone resorption 12 months after surgery. The results of the present study showed a significant reduction in CBH on both the proximal aspects at all the time intervals when “with flap” technique was used. The overall change in CBH was 1.48 mm on the mesial aspect and 1.42 mm on the distal aspect. Wood et al. reported bone loss ranging from 0.23 to 1.60 mm in 4–6 months following flap elevation.[3] Campelo and Camara [5] reported that bone resorption after using “with flap” technique is related to the thickness of the flap at the surgical site.

In this study, comparison of both the techniques showed significantly less bone loss with “flapless” than “with flap” technique. Similar findings were noted by Job et al.[21] as they observed the crestal bone loss of 0.06 mm with “flapless” technique and 0.4 mm “with flap” technique over a period of 3 months. Nickenig et al.[22] found that radiographic evaluation of marginal bone levels adjacent to implants showed comparable results with flapless (0.7–2.4 mm) and flap surgery (2–3 mm) during the healing period. Similar findings were also reported by Al-Juboori et al.[23]

Jeong et al.[24] conducted their study in dogs and after a healing period of 8 weeks they noted greater perimplant bone height (10.1 mm) with flapless technique than at open flap site (9.0 mm). The cumulative success rate for implants placed using a flapless one-stage surgical technique varied from 74.1% to 100% after a 10-year period in a retrospective analysis done by Campelo and Camara.[5]

Lesser crestal bone resorption with flapless technique is due to preservation of bone vascularization.[24]

As stated in the literature that in the “flapless” technique, the intact blood supply from soft tissue facilitates maintenance of nutrition, which is a critical factor in preventing initial bone loss around the implant. This also helps in maintaining the soft tissue architecture and hard tissue volume at the site.[6] There is accelerated recuperation, allowing the patient to assume normal hygiene procedures immediately as compared to sites where sutures are given. According to previous studies, early plaque control plays an important role in promoting the health of the periimplant mucosa and in preventing periimplant bone loss.[5],[25],[26] In addition to this, second stage surgical procedure is eliminated hence, total management time, number of visits and materials required are reduced.[27]

Jeong et al.[17] conducted a study on dogs and reported that flapless implant surgery increases the vascularity of periimplant mucosa and, therefore, increases the initial stability of an implant in comparison to implant placed after reflection of the mucoperiosteal flap.

The higher rates of bone loss at “with flap” sites were related to the fact that whenever a papilla is detached from bone, the interdental bone in proximity to the adjacent tooth is denuded from the periosteum. This can affect the nutrition of the bone and papillae resulting in an individually unpredictable degree of resorption of the interproximal crestal bone.[28] Sunitha et al.[29] also studied the effect of two different flap designs on CBH and stated that flap elevation leads to increased bone loss during the healing period.

Limitations of the study

Considering the limitations of the flapless technique, only ideal cases with adequate bone volume and normal bone contour were selected for the study. In this study, bone loss was measured only on mesial and distal sides of the implants. For more predictable results, total bone loss including that on buccal and lingual sides should also be measured. Small sample size and short observational period were also the limitations of our study.


Within the limitations of this study, it can be concluded that both the techniques lead to crestal bone loss but “flapless” procedure results in a lesser bone loss as compared to “open flap” technique. Therefore, the flapless technique can be considered as a better treatment approach for placement of implants, especially where adequate width and height of bone with ideal contours is available.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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