Immediate Implant Placement in the Esthetic Zone with Marginal Preservation: Esthetic Outcomes in Sites with Thin Buccal Bone Wall

Abstract

Purpose

To assess facial soft tissue levels and buccal bone thickness following immediate implant placement in compromised maxillary anterior sockets using marginal preservation technique.

Materials and Methods

A total of 49 patients with failing maxillary anterior teeth were assigned to single immediate implant placement using appropriately sized implants, combined with absorbable collagen matrix membrane and sticky demineralized freeze-dried bone allograft grafting. Definitive crown placement occurred 6 months after provisionalization. The primary outcome was the change in soft tissue levels, assessed using pink esthetic score (PES). Additionally, survival rates and buccal bone thickness were evaluated.

Results

The implant survival rate at 6-month follow-up was 100%. After 6 months, the overall PES significantly increased from 6.16 ± 2.23 to 7.31 ± 0.87 (p = 0.002). There was no statistically significant difference in esthetic outcomes between thick and thin gingival phenotypes. Implants with immediate provisionalization had a higher PES compared to those with delayed provisionalization (7.53 ± 0.76 and 7.04 ± 0.93, respectively, p = 0.041). A positive gain in buccal bone thickness was observed at 6-month post-surgery, and the timing of provisionalization (immediate versus delayed) did not significantly influence buccal bone thickness.

Conclusion

Immediate implant placement combined with a marginal preservation technique resulted in optimized esthetic outcome and positive changes in buccal bone thickness.

Introduction

Immediate implant placement (IIP) offers advantages such as reduced treatment time and fewer surgical interventions while achieving high survival rates and stable interproximal bone levels similar to those of delayed implant placements [1]. Although IIP can help preserve alveolar bone and enhance esthetic outcomes, clinical studies have reported notable bone or ridge alterations, as well as gingival recession. While these reductions are typically limited around 1 mm, more significant changes may occur, particularly in the esthetically sensitive maxillary region. Thus, meticulous case selection and thorough pre-surgical planning are essential to minimizing substantial bone and soft tissue changes.

The impact of buccal bone wall thickness on implant outcomes has been extensively studied, particularly in the context of IIP and the subsequent healing period of 3–6 months [2]. The maxillary anterior region, in particular, is characterized by predominantly thin buccal bone wall. Studies consistently report that in approximately 85% of anterior sites (incisors and canines), the buccal bone wall measures ≤ 1 mm, with fewer than 5% of these sites reaching the recommended 2 mm thickness [3]. Findings suggest that a buccal bone wall thickness at least 2 mm is widely recommended, as this threshold is considered critical. When the buccal bone is thinner, augmentation procedures are often required, particularly in the esthetically sensitive maxillary anterior region, to ensure long-term stability and optimal esthetic outcomes.

Preserving marginal bone is crucial for achieving a high pink esthetic score (PES), which depends on a combination of flapless techniques, guided bone regeneration, and appropriate immediate or delayed provisional restorations. For optimal outcomes in flapless post-extraction IIP, it is essential to incorporate a bone graft along with a contoured immediate or delayed provisional restoration [4]. Demineralized freeze-dried bone allograft (DFBA) has proven to be effective in both periodontal and bone reconstruction due to its osteoinductive properties. DFDBA enhances cell attachment, migration, and osteogenesis, primarily through the presence of bone morphogenic proteins that stimulate new bone formation during the healing process [5].

The objective of this study was to evaluate the esthetic soft tissue levels following IIP in compromised sockets, in combination with guided tissue regeneration and sticky DFDBA grafting, using a marginal preservation technique.

Materials and Methods

Study Design

The study protocol was approved by the Ethics Committee of Can Tho University of Medicine and Pharmacy (Vietnam) and adhered to the principles of the Declaration of Helsinki (Approval No. 23.318.HV/PCT-HDDD). Informed consent was obtained from all participants prior to their involvement in the study. The study was conducted between April 2023 and June 2024 at the Department of Odonto-Stomatology, Can Tho Eye, and Odonto-Stomatology Hospital.

Participants

Eligible patients over the age of 18 who presented with a failing central or lateral incisor in the maxillary incisor esthetic zone were invited to participate in the study and were fully informed about the study details. Inclusion criteria required that the extraction socket has a thin buccal bone wall (< 2 mm) and sufficient residual bone (at least 4 mm below the alveolus of the affected tooth) to ensure primary stability during implant placement. Exclusion criteria included patients with uncontrolled periodontitis, uncontrolled diabetes, parafunction habits, heavy smoking (more than 10 cigarettes per day), general contraindications to oral surgery, or refusal to sign the informed consent form.

Procedure of surgery

All surgical procedures were performed by the same experienced surgeon (T.H.T) (Fig. 1). After administering local anesthesia, bone sounding was conducted using a periodontal probe to assess the labial and lingual bone plate. Teeth were extracted with minimal trauma to preserve the alveolar bone, following carefully detachment of the periodontal ligament. The extraction socket was meticulously debrided to remove any soft or hard tissue lesions. A thin periosteal elevator (Buser Periosteal Elevator, Hu-Friedy, Chicago, IL, USA) was then used to gently detach soft tissue of labial site. The implant site was prepared on the palatal wall of socket according to the manufacturer’s guidelines. A Morse Taper implant (Neodent Helix GM^®, Straumann Group) was positioned slightly closer to the palatal wall, maintaining a horizontal jumping gap of at least 2 mm from the internal surface of the labial wall and vertical distance of 4 mm from the labial gingival margin. A healing cap with 4.5 mm diameter was then placed.

Fig. 1.

A typical case of study: a hopeless #21 tooth presented internal resorption; b implant was placed immediately into palatal bone plate of the socket with a jumping gap; c the appropriate depth of the implant; d a collagen membrane was placed and fixed; e sticky bone; f filling with sticky bone; g immediate provisionalization; h frontal view of definitive prosthetic; and i occlusal view of definitive crown

An absorbable collagen matrix membrane (Mucoderm^®, Biotiss, Germany) [6] was gently secured to labial site with double-parallel mattress suture technique [7] with an absorbable monofilament suture (Surgicryl^® Monofast 5.0, SMI, Belgium). A 2 mm tail of membrane was fixed using a customize healing abutment or temporary abutment. The jumping gap, labial bone, and membrane were overfilled with sticky bone (combination of platelet-rich fibrin and small particle DFDBA).

An immediate provisional restoration, without pressing grafting, was created based on the patients’ individual need. Finally, an adhesive dressing drop (PeriAcryl^®90HV, GluStitch, Canada) was added around the provisional tooth. All patients received a prophylactic dose of Augmentin 625mg (GlaxoSmithKline Pte., Ltd) 1 h before surgery and. Continued with Augmentin 625mg three times daily for 3-day postoperatively.

Procedure of Prosthesis

Six months after implant placement, radiographic evaluations were performed for all patients (Fig. 2). An open-tray impression was taken at the implant level using vinyl polysiloxane. Screw-retained or cement crowns were placed, secured with a torque of 20 Ncm.

Fig. 2.

Radiographic evaluation of a typical case: a pre-operative and b 6-month follow-up

Outcomes

Esthetic Assessment

Intraoral photographs were taken before tooth extraction, at implant placement (T0), and at prosthesis delivery (T6) to evaluate soft tissue changes. A digital SLR camera (6D Mark II, Canon, Japan) was used with a fixed angle and magnification ratio. The crown length of contralateral tooth served as a reference for assessing soft tissue level changes around the implant. To measure soft tissue alterations, a line was drawn from the incisional margin of teeth adjacent to implant, and perpendicular lines were extended from this reference line to the mid-buccal gingival margin [8]. The changes in these line lengths over time were used to quantify soft tissue modifications.

The Pink esthetic score (PES) was utilized to assess peri-implant soft tissue esthetics, considering five factors: mesial papilla, distal papilla, soft tissue level, facial mucosa curvature, and root convexity/soft tissue color and texture [9]. Each parameter was rated on a scale from 0 to 2, with 2 indicating optimal and 0 indicating the poorest outcome. The total PES was calculated by summing the individual scores.

Radiograph evaluation

Sagittal CBCT images were acquired using a CBCT machine (Hyperion X5, Myray, Italia) along the implant axis to assess the thickness of the labial bone plate for all implant at 6-month post-operation. The labial bone plate thickness was measured as the distance between the implant’s facial contour and the outer surface of the labial bone at the level of the implant shoulder (M0), as well as at 1, 2, 3, 4, and 5 mm apical to the implant shoulder (M1, M2, M3, M4, and M5) [10].

Statistical Analysis

Mean values and standard deviations were calculated for all parameters. The Wilcoxon signed-rank test (to compare paired-groups’ mean) and the Mann–Whitney U test (to identify significant differences between groups) were used for nonparametric data. Statistical analysis was conducted using SPSS software ver.23.0, with the significance threshold set at 0.05.

Results

A total of 49 patients (26 men and 23 women) with 49 immediate implants (37 central and 12 lateral implants) were included in the study. The patients’ ages ranged from 18 to 69, with a mean age of 38.37 ± 15.09 years. The distribution of implant diameters was nearly equal, with narrow implants (Ø3.5 mm) used in 26 cases and regular-diameter implants (Ø3.75 mm) in 23 cases. All implants had primary stability with torque ≥ 35 Ncm.

A thick gingival biotype was observed in 37 cases, while a thin biotype was present in 12 cases. The balanced use of immediate and delayed provisionalization (23 and 26 case, respectively) indicates a selective approach based on primary stability and patient-specific factors. Cement-retained restorations were predominantly used in 42 cases, while screw-retained restorations were employed in seven cases.

Implant Survival RATE

At 6 months, all implants remained with no sign of mobility, resulting in a 100% survival rate.

Pink Esthetic Score (PES)

The components of the PES were compared between baseline and 6-month post-surgery (Table 1). Notably, significant improvements were observed in the distal papilla, facial curvature, and root color/texture, reflecting a positive change in the natural appearance of the soft tissue at 6-month post-operation. The overall PES increased significantly from 6.16 at baseline to 7.31 at 6 months.

Table 1.

Comparison of the mean PES between pre-extraction and 6 months after surgery

	Mean (Median) ± SD		p value
	Baseline	6 months
Mesial papilla	1.14 (1) ± 0.58	1.20 (1) ± 0.50	0.513
Distal papilla	1.02 (1) ± 0.59	1.31 (1) ± 0.51	0.002b
Margin level	1.47 (2) ± 0.62	1.59 (2) ± 0.54	0.157
Curvature	1.41 (2) ± 0.73	1.80 (2) ± 0.41	0.002b
Root/color/texture	1.12 (1) ± 0.83	1.41 (1) ± 0.50	0.040a
PES	6.16 (7) ± 2.23	7.31 (7) ± 0.87	0.002b

^ap < 0.05, ^bp < 0.01, ^ap < 0.05, statistically significant difference

Table 2 shows that immediate provisionalization led to a statistically significant improvement in the overall PES compared to delayed provisionalization, highlighting the esthetic benefits of immediate temporary restorations.

Table 2.

Comparison of the mean PES between groups of immediate provisionalization

	Mean (Median) ± SD		p value
	Delayed provisionalization	Immediate provisionalization
Mesial Papilla	1.09 (1) ± 0.52	1.31 (1) ± 0.47	0.140
Distal Papilla	1.43 (1) ± 0.51	1.19 (1) ± 0.49	0.103
Margin level	1.43 (1) ± 0.59	1.73 (2) ± 0.45	0.062
Curvature	1.74 (2) ± 0.45	1.85 (2) ± 0.37	0.359
Root/Color/Texture	1.35 (1) ± 0.49	1.46 (1) ± 0.51	0.424
PES	7.04 (7) ± 0.93	7.53 (7) ± 0.76	0.041a

^ap < 0.05, statistically significant difference

The thick phenotype demonstrated more favorable, though not statistically significant, outcomes in than thin phenotype in overall PES compared to the thin phenotype (Table 3). The root/color/texture component was significantly higher in the thick phenotype than in the thin phenotype. However, the margin level was significantly lower in the thick phenotype.

Table 3.

Comparison of the mean PES between groups of gingival phenotype at 6-month post-surgery: Mann–Whitney test

	Mean (Median) ± SD		pvalue
	Thin phenotype	Thick phenotype
Mesial Papilla	1.19 (1) ± 0.52	1.20 (1) ± 0.50	0.757
Distal Papilla	1.35 (1) ± 0.54	1.31 (1) ± 0.51	0.239
Margin level	1.68 (2) ± 0.53	1.59 (2) ± 0.54	0.033a
Curvature	1.76 (2) ± 0.44	1.80 (2) ± 0.41	0.237
Root/Color/Texture	1.30 (1) ± 0.46	1.41 (1) ± 0.50	0.006b
PES	7.27 (7) ± 0.96	7.31 (7) ± 0.87	0.870

^ap < 0.05, ^bp < 0.01, statistically significant difference

Buccal Bone Thickness

The timing provisionalization (immediate versus delayed) did not significantly influence buccal bone thickness around implant 6 months after surgery (Table 4).

Table 4.

Comparison of buccal bone thickness between groups of immediate provisionalization and delayed provisionalization

	Median [interquartile range] (mm)		P-value
	Delayed provisionalization	Immediate provisionalization
M0 (at neck)	2.05 [1.77;2.48]	2.31 [1.75;2.57]	0.378
M1	1.84 [1.72;2.38]	2.18 [1.81;2.50]	0.331
M2	1.78 [1.68;2.17]	2.05 [1.74;2.33]	0.367
M3	1.87 [1.69;2.07]	2.01 [1.80;2.31]	0.241
M4	1.85 [1.62;2.07]	2.07 [1.80;2.29]	0.176
M5	1.89 [1.77;1.98]	2.01 [1.79;2.23]	0.341

Discussion

Tooth extraction is frequently associated with dehiscence or fenestration defects in the alveolar bone. These defects, particularly on the mid-facial side, often lead to significant ridge reduction, making immediate implant placement challenging [11]. In this study, we employed flapless surgery combined with guide bone regeneration to address alveolar ridge resorption during immediate implant placement in compromised fresh sockets. Both esthetic outcomes and radiographic evaluations were conducted to assess the results.

Forty-nine implants were installed in the study, achieving a 100% implant survival rate with favorable results. Excellent soft tissue esthetic outcomes, as measured by the PES, were observed within 6 months. This aligns with previous studies where guided bone regeneration (GBR) conducted simultaneously, suggesting that IIP combined with concurrent GBR and bone grafting is a viable treatment option for compromised extraction sites as thin or not buccal bone wall [12]. Notably, the mean PES in this study was comparable to previous findings. This similarity may be due to the contouring advantages offered by absorbable collagen matrix membrane and sticky DFDBA substitutes.

Implant position planning should account for both site-specific anatomical landmarks and the dimensional changes that occur post-extraction [13]. Narrow implants are often chosen in areas with limited bone width or in esthetically demanding anterior zones, e.g., later incisor positions, to conduct the minimum horizontal gap or jumping gap distance of 2 mm. A carefully managed distance can provide both function stability and esthetic advantages where any bone and gum tissue changes are visible [14].

This study utilized the PES to assess and validate the esthetic outcomes in patients, based on evaluations from dental images (Table 1).

They highlighted the positive impact of the IIP and augmentation technique on the esthetics of peri-implant tissues. Chan et al. [15] reported that IIP, with or without provisionalization, can maintain a stable vertical soft tissue level relative to the pre-extraction level. Slagter et al. [16] observed an increase in the mean PES from 7 to 7.83 after 5 years of treatment in both groups, with or without immediate provisional restoration.

The immediate provisionalization significantly effected to the overall PES more than its delay (Table 2). This study underscores the value of immediate provisionalization in enhancing the esthetic outcome of peri-implant tissues, supporting its use when stability and soft tissue conditions permit. Bhutani et al. [17] exhibited that the immediate provisionalization of IIP with or without bone grafts preserved stability of soft tissues and hard tissue giving better esthetic results. Cirmeni et al. [18] showed that the sticky bone in immediate implants helps to avoid destruction of hard and soft tissue and promotes faster and more robust healing. After 2 years, the facial and interdental soft tissues were successfully preserved. Xie et al. [19] reported that the sticky bone with concentrated growth factors achieved superior bone augmentation compared to conventional GBR. It facilitates the mean bone volume conversion rate, more patients’ comfort. The combination of immediate implants with DFDBA using marginal preservation approach showed a reduction in crestal bone height, and an increasing in buccal bone thickness which positively impacts tissue stability and overall esthetics [5]. Pohl et al. [20] also reported in a pilot study that the absence of buccal bone wall did not appear to contraindicate immediate implant placement and restoration, as long as the initial esthetic conditions are satisfactory.

The margin level of thin phenotype was significantly higher than thick phenotype (Table 3). This may from marginal preservation approach of IIP to prevent loss the buccal mucosa margin [21]. The primary factor contributing to buccal mucosa recession is likely the resorption of buccal bone. Factors that threaten the stability of the buccal bone wall include a thin or deficient buccal bone plate and implant positioning compromising the buccal bone wall. Furthermore, in this study, the collagen matrix membrane was applied due to the tissue contours favorable, connective tissue graft is not necessary during the IIP [6]. These final restoration contours are established in the initial fixed prosthetics and replicated contours in the final prosthesis, enhancing tissue stability [21].

The immediate provisionalization also kept the buccal bone wall higher than its delayed but not significant (Table 4). The results are relevant for clinical decision-making, choosing the timing of provisionalization based on other factors, such as esthetic goals or patient preferences, without compromising buccal bone stability [15]. The immediate provisional may preserve buccal bone by reducing dimensional changes at 6-month post-surgery [22]. Slagter et al. [16] supported that the immediate provisionalization contributes to better preservation of the buccal bone layer than delayed provisionalization in a 5-year comparative study.

Conclusion

Based on the 6-month follow-up, this study suggests that IIP with GBR, using a marginal preservation technique, is a viable treatment option for compromised extraction sockets with a thin buccal bone wall in the anterior region. However, further research is necessary to assess long-term tissue changes.

Author contributions

All authors contributed equally to this manuscript.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not for-profit sectors.

Data availability

Available on request from the corresponding author, Lam Nguyen Le (lenguyenlam@ctump.edu.vn).

Declarations

Conflict of interest

The authors declare no conflicts of interest.

Informed consent

All operations have earned informed consent filled by the patients.