Fabrication of a CAD-CAM Custom Modified Anatomic Healing Abutment based on Gingival Profile Measurement in an Instructional Dentition Model - A Dental Technique

Introduction

In recent years, the field of dental implant restoration has witnessed a growing emphasis on esthetic restoration. The concept of esthetic dental implant restoration entails achieving a seamless integration between the prosthesis and the surrounding soft tissue after implantation, such that it becomes visually indistinguishable from the natural dentition. The key to accomplishing this esthetic outcome lies in maximizing the preservation or reconstruction of the soft tissue surrounding the implant.

To ensure the stability of the soft tissue surrounding the implant, esthetic dental implant restoration begins with the placement of a healing abutment. These healing abutments typically possess a circular cross-section and are predominantly composed of titanium [1, 2]. To achieve an optimal soft tissue profile around the implant, the shape of the healing abutment should closely resemble that of the natural tooth’s cervical region [3]. However, circular healing abutments lack the contour characteristic of a natural tooth, resulting in an imperfect peri-implant soft tissue profile when employed for shaping purposes. Consequently, a subsequent surgical intervention is required to reshape the soft tissue [4].

To address this issue, implantologists have implemented personalized healing abutments in clinical settings [5, 6, 7, 8, 9]. Personalized healing abutments facilitate early restoration of the gingival contour curve, eliminating the need for a secondary procedure and reducing the risk of premature detachment [5, 6, 7, 8]. These abutments are custom-made to match the natural tooth profile, preserving the original gingival structure and providing insulation for the bone graft material at the extraction site during immediate implantation [5, 7]. Numerous researchers have proposed different techniques for creating customized healing abutments to maintain gum contour [8, 9, 10, 11, 12]. We hypothesize that anatomic healing abutments that closely emulate the shape of the tooth neck are more effective for immediate implantation. Therefore, this study focuses on the mandibular first molar as exemplary cases, aiming to design and manufacture improved anatomic healing abutments based on the amount of alveolar bone absorption after tooth extraction. These abutments will be utilized to shape the pre-implant gingival contour. This innovative design methodology holds promising prospects for successful implementation in clinical trials.

Technique

1. The single mandibular first molars were extracted from the dental models (Shanghai Xinmanke Teaching Equipment Co., LTD., China) Figure 1a to expose the neck cross-section of tooth (Figure 1b).
2. Experimental implants (Beijing Daqing Biotechnology Co., LTD., China) were inserted into the vacant cross- sections using red wax (Figure 1c). A scanning abutment (Beijing Daqing Biotechnology Co., LTD.,) China was placed alongside implant within the cross-section (Figure 1d).
3. The dental models were scanned using a Shining 3D Scanner (oralscan2, SHINING 3D Technology Co., LTD., China).
4. A digital caliper (Mitutoyo 500-196-30, Shenzhen Sanjian Precision Measuring Instrument Co., LTD., China) was employed to measure the cervical cross-sectional dimensions of the mandibular first molar on the dental models, as depicted in Figure

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Figure 2: Gingival contour measurement of mandibular first molar. Line A is the distance between the proximal and distal of the gingival contour, line B is the distance of the buccolingual of the gingival contour, line C is the distance from the proximal buccal of gingival contour to the distal lingual gingival contour through the focal points of AB, and line D is the distance from the proximal lingual of gingival contour to the distal buccal gingival contour through the focal points of AB.

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Discussion

The report introduced a modified anatomic healing abutment characterized by a slightly concave profile, resembling the contour of the tooth neck. Implementation of this type of healing abutment has the potential to enhance peri-implant gingival esthetics and contour, thereby yielding superior final esthetic outcomes when compared to circular healing abutments [4, 6, 14, 15, 16]. The utilization of personalized healing abutments is progressively being documented in clinical practice, encompassing both esthetic and non-esthetic contexts [5, 6, 7, 8]. For instance, Raheem IMA, et al. [11] employed X-ray film to measure the distance from the implant shoulder to the proximal and distal root of the tooth, as well as the crest of the buccal and lingual alveolar crest. After adjusting the acquired data, a CAD/CAM system was employed to design a customized healing abutment. Some researchers have utilized CAD/CAM systems or manual methods in conjunction with silicone impressions or oral scans to fabricate personalized healing abutments [1, 2, 8, 17]. These techniques have proven effective and are gaining popularity among both dentists and patients. However, they necessitate additional equipment, such as CAD/CAM, and involve chair-side fabrication, which heightens the risk of patient infection, prolongs chair-side operation times, and incurs supplementary costs.

The dentition model manufactured by Shanghai Xinman Science Teaching Equipment Co., Ltd. in China provides the opportunity to acquire the dimensions of the tooth neck cross-section (lines A, B, C, D). For this investigation, the mandibular first molars were chosen as representative examples. Based on the neck morphology of the model teeth and the buccal bone plate absorption subsequent to tooth extraction, the cross-section of the modified anatomic healing abutment for the mandibular first molar was designed as a rounded rectangle. The goal was to closely replicate the natural tooth’s neck shape. The enhanced anatomical form of the healing abutment offers improved shaping of the peri- implant soft tissue profile. Generally, the majority of healing abutments are fabricated from biocompatible titanium [1, 2]. However, some researchers [9] have explored the use of zirconia ceramics for healing abutments due to their superior soft tissue esthetic characteristics [18] and reduced bacterial adhesion to zirconia ceramic surfaces [19]. In the subsequent clinical trial, a Datsing implant with a tapered connection was employed for the abutment. Shota [20] discovered that zirconia-based abutments exhibited lower fracture resistance compared to titanium-based abutments in cone-connected implants. Therefore, in this study, grade 5 titanium was chosen as the raw material for producing the modified anatomic healing abutment. Furthermore, since the healing abutment serves as a temporary tool for shaping the gingiva, aesthetic requirements are minimal.

Acknowledgement

This report received support from the Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region (grant no. NJYT 23064), the First-class Scientific Research Fund Project of Stomatology School of Chifeng University (grant no. KQYXYYLXK 202101), and the Chifeng University Affiliated Hospital research project (grant no. FSYY2022-20).

Competing Interest

The authors declare no competing interests.