Ratio between Height and Thickness of the Buccal Tissues: A Pilot Study on 32 Single Implants

Association of Peri-Implant Mucosa Dimensions With Emergence Profile Angles of the Implant Prosthesis

OBJECTIVES

The primary aim of this cross-sectional study was to investigate the association between prosthesis design and peri-implant mucosa dimensions and morphology. The secondary aim was to investigate associations between mucosal dimensions and the presence of mucositis.

MATERIALS AND METHODS

Forty-seven patients with 103 posterior bone level implants underwent clinical and radiographic examination, including cone beam computer tomography and intraoral optical scanning. Three-dimensional models for each implant and peri-implant mucosa were constructed. Vertical mucosa height (TH), horizontal mucosa width at implant platform (TW), and 1.5 mm coronal of the platform (TW1.5), as well as mucosal emergence angle (MEA), deep angle (DA), and total contour angle (TA) were measured at six sites for each implant.

RESULTS

There was a consistent correlation between peri-implant mucosa width and height (β = 0.217, p < 0.001), with the width consistently surpassing height by a factor of 1.4-2.1. All three angles (MEA, DA, TA) were negatively associated with mucosa height (p < 0.001), while DA was negatively associated with mucosa width (TW1.5) (p < 0.001, β = -0.02, 95% CI: -0.03, -0.01). There was a significant negative association between bleeding on probing (BoP) and mucosa width at platform (OR 0.903, 95% CI: 0.818-0.997, p = 0.043) and 1.5 coronal (OR 0.877, 95% CI: 0.778-0.989, p = 0.033). Implants with less than half sites positive for BoP (0-2/6) had significantly higher mucosa height (OR 3.51, 95% CI: 1.72-7.14, p = 0.001).

CONCLUSIONS

Prosthesis design can influence the dimensions of the peri-implant mucosa, with wider emergence profile angles associated with reduced peri-implant mucosa height. In particular, a wider deep angle is associated with reduced mucosa width in posterior sites. Reduced peri-implant mucosa height and width are associated with more signs of inflammation.

TRIAL REGISTRATION

Registered in Thai Clinical Trials Registry: http://www.thaiclinicaltrials.org/show/TCTR20220204002.

A Novel Prehydrated Porcine-Derived Acellular Dermal Matrix: A Histological and Clinical Evaluation

It is well known that soft tissue quality and quantity around dental implants is of paramount importance for later peri-implant health. For this purpose, the clinical and histological outcomes of the peri-implant mucosa, following soft tissue augmentation for soft tissue improvement with a novel prehydrated porcine acellular dermal matrix graft (PPADMG) in conjunction with simultaneous implant placement, were evaluated in this case series. Twenty-two patients were included in the study. They underwent a late implant placement protocol combined with PPADMG for soft tissue augmentation. A punch biopsy was taken at the time of uncovery of the submerged healed implant after a mean of 157 days healing time. Supracrestal soft tissue height (STH) was measured at the time of implant placement and uncovery. All sites showed a clinical increase in STH. The histological structure of the biopsies resembled a similar structure as found in the healthy oral mucosa. No unexpected tissue reactions could be found. Within the limits of this clinical and histological study, it may be concluded that STH improvement with this novel porcine-derived acellular dermal matrix, in combination with simultaneous implant placement, is a viable option to create a peri-implant tissue thickness and stability.

Soft tissue dimensional change using customized titanium healing abutment in immediate implant placement in posterior teeth

BACKGROUND

The morphologic and dimensional alveolar bone is significant for resorption in the first 3 months after tooth removal because they restrict treatment outcomes with respect to function and esthetic. Following teeth extraction, the width and height of the alveolar ridge contour are reduced in both the horizontal and vertical dimensions. Following implant placement, the gingival morphology should be changed minimally compared to pre-extraction. Surrounding natural-like tissue is also an ultimate goal of the dental implant treatment, which is correlated with the cervical third contour on the anatomical tooth, for comfortable cleansing, food impaction avoidance, and esthetics.

PURPOSE

To evaluate the peri-implant soft tissue changes after immediate implant placement (IIP) with the use of a customized titanium healing abutment in the posterior teeth.

METHOD

Digital impressions using the intraoral scanner (MEDIT i500) were taken from 30 patients. Customized titanium healing abutments were designed and milled before extraction. Flapless extractions were done using surgical guides, 32 immediate implants placement were done in posterior areas, and healing abutments were placed. Soft tissues were scanned during pre-operation, and post-surgery during the 1st, 3rd, and 6th months. A 3D analysis program (Final Surface) evaluated the gingival margin distance, height, contour width, and volume in each period. SPSS was used to analyze the data with a p-value = 0.05. The between-time interval comparisons were done and the analysis was done using a Multivariate test.

RESULTS

Customized titanium healing abutments used in immediate implantation maintained optimal peri-implant mucosa. In intermittent periods, there was no significant reduction in all aspects of the margin distances and heights. During the entire period, the margin height reduction on the buccal, lingual, mesial, and distal was 0.63 mm, 0.93 mm, 0.08 mm, and 0.24 mm, respectively, and contour width reduction on the buccal, lingual, and buccolingual was 0.59 mm, 0.43 mm, and 1.03 mm, respectively. There was a significant reduction in the total buccolingual contour width in the 1st month and total volume in the 3rd to 6th months.

CONCLUSIONS

Immediate implant placement with customized titanium healing abutment can achieve the optimal peri-implant mucosa and this protocol is an alternative for soft tissue management.

Effect of the prosthetic index on stress distribution in Morse taper connection implant system and peri-implant bone: a 3D finite element analysis

Background

The combination of a prosthetic index with Morse taper connection was developed, with the purpose of making prosthetic procedures more precise. However, the presence of the index may compromise the mechanical performance of the abutment. The aim of this study is to evaluate the effect of prosthetic index on stress distribution in implant–abutment-screw system and peri-implant bone by using the 3D finite element methodology.

Methods

Two commercial dental implant systems with different implant–abutment connections were used: the Morse taper connection with platform switching (MT-PS) implant system and the internal hex connection with platform matching (IH-PM) implant system. Meanwhile, there are two different designs of Morse taper connection abutment, namely, abutments with or without index. Consequently, three different models were developed and evaluated: (1) MT-PS indexed, (2) MT-PS non-indexed, and (3) IH-PM. These models were inserted into a bone block. Vertical and oblique forces of 100 N were applied to each abutment to simulate occlusal loadings.

Results

For the MT-PS implant system, the maximum stress was always concentrated in the abutment neck under both vertical and oblique loading. Moreover, the maximum von Mises stress in the neck of the MT-PS abutment with index even exceed the yield strength of titanium alloy under the oblique loading. For the IH-PM implant system, however, the maximum stress was always located at the implant. Additionally, the MT-PS implant system has a significantly higher stress level in the abutment neck and a lower stress level around the peri-implant bone compared to the IH-PM implant system. The combined average maximum stress from vertical and oblique loads is 2.04 times higher in the MT-PS indexed model, and 1.82 times for the MT-PS non-indexed model than that of the IH-PM model.

Conclusions

MT-PS with index will cause higher stress concentration on the abutment neck than that of without index, which is more prone to mechanical complications. Nevertheless, MT-PS decreases stress within cancellous bone and may contribute to limiting crestal bone resorption.

Full Digital Model-Free Maxillary Prosthetic Rehabilitation by Means of One-Piece Implants: A Proof of Concept Clinical Report with Three-Years Follow Up

Implant rehabilitation is a daily practice in dentistry, and patients often have heightened expectations regarding both the functional and the aesthetic outcome. Implant–abutment connection (IAC) is involved in the long-term aesthetic quality of the rehabilitation. The use of one-piece implants for fixing dentures may prevent the mechanical and biological implication of the implant–abutment interface, resulting in a better quality of hard and soft tissue maintenance. In this case report, we present a novel one-piece implant in a maxillary rehabilitation with a full model-free digital approach.

Behavior of Soft Tissue around Platform-Switched Implants and Non-Platform-Switched Implants: A Comparative Three-Year Clinical Study

To verify the influence of platform-switching (PS) on soft tissue behavior by comparing the soft tissue stability around implants with and without PS, during three years of follow-up. The study included patients treated with fixed dentures supported by implants with an internal connection. The radiographic distance between the first bone-to-implant contact (FBIC) and the implant shoulder was assessed. Additionally, the presence of keratinized facial mucosa and the prosthetic crown height (TH) were monitored for three years from the delivery of the definitive crown. These parameters were measured for two different groups: platform-switched implants in the PS group and non-platform-switched (NPS) implants in the NPS group. Seventy-seven implants were considered in the statistical analysis. After three years, the overall FBIC mean value was 0.31 ± 1.00 mm. However, the mean FBIC was 0.66 ± 0.97 mm for the NPS group and -0.05 ± 0.91 mm for the PS group. Moreover, a mean recession of 0.54 ± 1.39 mm was measured for the NPS group, whereas a mean coronal migration of 0.17 ± 0.95 mm was measured for the PS group. A significant correlation was also found between the presence of PS and ΔTH (p ≤ 0.01) over the three years of follow-up. The absence or presence of platform-switching would appear to affect the tendency of the gingival buccal margin towards recession or creeping. Additionally, implant-abutment platform-switching seems to help prevent peri-implant soft tissue recession over time when compared to implants without PS.

Can transfer type and implant angulation affect impression accuracy? A 3D in vitro evaluation

Impression accuracy is fundamental to achieve a passive fit between implants and the superstructure. Three transfer types were tested to evaluate the differences in impression accuracy and their efficiency in case of different implant angles. A master model with four implant analogues placed at 0°, 15° and 35° was used. 27 impressions were taken with three different types of impression coping: closed tray technique coping (CT), open tray technique coping (COT) and telescopic open tray coping (TOT). The impressions were poured. Analogues were matched with scan bodies to be scanned and exported in STL. An implant bar was designed from each STL and another one from the master model. A comparison between these bars was obtained. Linear and angular measurements for every type of coping were calculated for different angulations. The collected data were analyzed with ANOVA test (95% of confidence). Student’s t test showed a significative discrepancy (p ≤ 0.001) on linear and angular measurements on Δx, Δy, Δz with different transfer types as well as diverse implant positioning angles (p ≤ 0.001). Within the limitations of this study, it can be concluded that the coping type and the implants divergence may be significant parameters influencing the impression accuracy.

Influence of the implant-abutment connection on the ratio between height and thickness of tissues at the buccal zenith: a randomized controlled trial on 188 implants placed in 104 patients

Background

To compare tissue response to two implant systems, featuring internal hexed connections with different designs.

Methods

Patients enrolled in this randomized controlled trial were assigned to two groups. In Group 1, patients were treated with implants with a 5° conical internal hexed connection (Anyridge®, MegaGen, South Korea). In Group 2, patients were treated with implants with an internal hexed connection (Core®, Kristal, Italy). After implant placement and a provisionalisation period of 12 months, impressions were taken, stone casts were poured and digitised with a desktop scanner (D700®, 3Shape, Copenhagen, Denmark). In a digital environment, for each fixture, two values were collected at the buccal zenith: the height of the peri-implant mucosa (mucosal height; MH), calculated from the vestibular shoulder of the implant analogue to the upper gingival margin of the supra-implant tissue; and the width of the peri-implant mucosa (mucosal thickness; MT), calculated from the vestibular shoulder of the analogue to the external mucosa point perpendicular to the implant major axis. The mean and standard deviation for MH and MT, as well as their ratios, were calculated for each group; the sectors in which the implants were placed were also considered. Finally, correlation between MH, MT, connection type and sector was assessed by Pearson’s correlation coefficient, with significance level set at 0.05, and a confidence interval (CI) set at 95%.

Results

Data deriving from 188 implants placed in 104 patients were evaluated. The mean MH values were 3.32 (± 0.12) and 2.70 (± 0.16) mm for Groups 1 and 2, respectively. The mean MT values were 4.37 (± 0.16) and 3.93 (± 0.18) mm for Groups 1 and 2, respectively. Group 1 showed higher MH and MT values and a better ratio (1.50 ± 0.88) than Group 2 (1.81 ± 1.20). The MH, MT and MH/MT ratio were significantly influenced both by sector (p = 0.015) and group (p = 0.047).

Conclusions

Within the limits of this study, the 5° connection implants supported a more extended tissue height and thickness at the buccal zenith, and a better ratio between them.

Trial registration

This study was retrospectively registered in Clinicaltrials.gov, with number NCT04160689, dated 13/11/2019.

Correlation between Buccal Bone Thickness at Implant Placement in Healed Sites and Buccal Soft Tissue Maturation Pattern: A Prospective Three-Year Study

Background: Optimal aesthetic implant restoration is a combination of a visually pleasing prosthesis and adequate surrounding peri-implant soft tissue architecture. This study describes the influence of the residual buccal bone thickness (BBT), measured at the time of implant placement, on the soft tissue maturation during three years of follow-up. Methods: Seventy-eight implants were enrolled in the present study. The BBT was assessed at the surgical stage and each case assigned to Group 1 (BBT values ≤0.5 mm), Group 2 (BBT values >0.5 and <1.5 mm), or Group 3 (BBT values ≥1.5 mm). Only native bone and healed sites were included. The tooth height (TH), based on the distance between the buccal free gingival margin at the zenith level and the crown incisal edge, according to the main axis of the tooth, was monitored at one, two, and three years from the final prosthodontic rehabilitation to determine any occurrence of recession or coronal repositioning of the gums over time. A Pearson Two-Tailed test was applied and the significance level set at p ≤ 0.05. Results: For BBT values ≤0.5 mm, the buccal gum at three years showed an average recession of 1.22 ± 0.41 mm. For BBT values >0.5 and <1.5 mm, the buccal gum also showed recession of 0.64 ± 0.29 mm. In contrast, for BBT values ≥1.5 mm, the buccal gum showed coronal growth of 0.77 ± 0.22 mm. The differences between the groups were significant (p ≤ 0.01) at all times. Conclusion: The BBT at the time of implant placement was found to affect the buccal gingival margin stability over three years of observation.

Peri-Implant Soft Tissue Conditioning by Means of Customized Healing Abutment: A Randomized Controlled Clinical Trial

INTRODUCTION

An optimal aesthetic implant restoration is a combination of a visually pleasing prosthesis and adequate surrounding peri-implant soft tissue architecture. This study describes a novel workflow for one-step formation of the supra-implant emergence profile.

MATERIALS AND METHODS

Two randomized groups were selected. Ten control group participants received standard healing screws at the surgical stage. Ten individualized healing abutments were Computer aided Design/Computer aided Manufacturing (CAD/CAM)-fabricated out of polyether ether ketone (PEEK) restoration material in a fully digital workflow and seated at the surgical stage in the test group. The modified healing abutment shape was extracted from a virtual library. The standard triangulation language (STL) files of a premolar and a molar were obtained considering the coronal anatomy up to the cement-enamel junction (CEJ). After a healing period ranging from 1 to 3 months depending on the location of the surgical site, namely, mandible or maxilla, a digital impression was taken. The functional implant prosthodontics score (FIPS) and the numerical rating scale (NRS) of pain were recorded and compared.

RESULTS

The mean FIPS value for the test group was 9.1 ± 0.9 while the control group mean value was 7.1 ± 0.9. In the test group, pain assessment at crown placement presented a mean value of 0.5 ± 0.7. On the contrary, the control group showed a mean value of 5.5 ± 1.6.

CONCLUSIONS

Patients in the test group showed higher FIPS values and lower NRS scores during the early phases compared to the control group.