OBJECTIVE: The aim of this study was to evaluate the accuracy of 3-dimensional (3D)-printed surgical guides for fully guided immediate implants from different manufacturers.
METHODS: Eighteen 3D printed fully guided surgical guides (split into 3 groups [n = 6] according to their manufacturer: Company, Desktop, or Lab), were used to place 72 implants (n = 24) in identical maxillary models. After placement, the mean global, angular, mesiodistal, buccopalatal, and vertical deviation at the platform and apex of the placed implants, relative to their preoperatively planned positions, was calculated.
RESULTS: Significant differences in global apex deviation, angular deviation, mesiodistal apex deviation, and vertical platform and apex deviation were found between the Lab and Desktop groups (p ≤ 0.007). Significant differences in mesiodistal platform and apex deviation and buccopalatal apex deviation were also found between the Company and Desktop groups (p ≤ 0.005). Finally, significant differences in buccopalatal apex deviation, and vertical platform and apex deviation were found between the Company and Lab groups (p ≤ 0.003). Mean differences between guide groups across all parameters never exceeded 0.5 mm or 1°.
CONCLUSIONS: The choice of 3D printer has a significant effect on the accuracy of fully guided immediate implants. However, the clinical relevance of these differences may be considered limited.

Purpose - Compare the morphometric results of immediate implants (Type 1C) with a cylindrical (conventional) or triangular neck, in the anterior region of the maxilla, during 6 months of osseointegration. Materials and Methods - Prospective randomized clinical trial with a sample of 20 individuals randomly assigned to each group (10 triangular neck implants and 10 cylindrical neck implants). Consecutively direct measurements were performed: before (T-1) and after tooth extraction (T0), after implant placement (T1), after 1 month of the submerged implant healing (T2), when placing the healing abutment (T3), after placing the definitive crown (T3), and after 6 months of osseointegration (T4). Results - A significant difference between T1 and T3 in the buccal cortical thickness was identified (0.49Å}0.86mm). Although there was a significant increase in the buccal cortical thickness in both implants, this increase was greater for the triangular neck implants (cylindrical shape: 0.08Å}0.59 vs. triangular neck 0.90Å}0.91mm). It was also observed that implants placed below the buccal bone crest (í-1mm) promote less vertical buccal bone loss than implants placed Ñ-1mm at crest level (-0.65Å}0.52mm vs. -1.42Å}0.86mm). This observation needs to be further investigated in additional studies. Conclusions - The triangular neck implants present an increase in the cortical buccal thickness compared to the cylindrical implants. However, this increase does not fully compensate the remodulation after tooth loss.

OBJECTIVE: To compare connective tissue graft (CTG) with collagen matrix (CMX) in terms of increase in buccal soft tissue profile (BSP) when applied at single implant sites.
METHODS: Patients with a single tooth gap in the anterior maxilla and horizontal mucosa defect were enrolled in a multi-centre randomized controlled trial. All were fully healed sites with a bucco-palatal bone dimension of at least 6 mm, and received an immediately restored single implant using a full digital workflow. Patients were randomly allocated to the control (CTG) or test group (CMX: Geistlich Fibro-Gide, Geistlich Pharma AG, Wolhusen, Switzerland) to increase buccal soft tissue thickness. Primary endpoints were increase in BSP at T1 (immediately postop), T2 (3 months), T3 (1 year) and T4 (3 years) based on superimposed digital surface models. Secondary endpoints included patient-reported, clinical and aesthetic outcomes.
RESULTS: Thirty patients were included per group (control group: 15 males, 15 females, mean age 50.1 years; test group: 14 males, 16 females, mean age 48.2 years) and 50 could be re-examined at T4. The changes in BSP over time were significantly different between the groups (p < .001). At T4, the estimated mean increase in BSP amounted to 0.83 mm (95% confidence interval [CI]: 0.58-1.08) in the control group and 0.48 mm (95% CI: 0.22-0.73) in the test group. The estimated mean difference of 0.35 mm (95% CI: 0.06-0.65) in favour of the control group was significant (p = .021). No significant differences between the groups could be observed in terms of patients\' aesthetic satisfaction (p = .563), probing depth (p = .286), plaque (p = .676), bleeding on probing (p = .732), midfacial recession (p = .667), Pink Esthetic Score (p = .366) and Mucosal Scarring Index (p = .438). However, CMX resulted in significantly more marginal bone loss (-0.43 mm; 95% CI: -0.77 to -0.09; p = .015) than CTG.
CONCLUSIONS: CTG was more effective in increasing buccal soft tissue profile and resulted in less marginal bone loss than CMX. Therefore, CTG remains the gold standard to increase soft tissue thickness at implant sites.
BACKGROUND: This study was registered in ClinicalTrials.gov (NCT04210596).

OBJECTIVE: To assess the impact of the timing of implant placement following alveolar ridge preservation (ARP) on the need for soft-tissue augmentation (STA) and to identify the risk factors for horizontal and vertical soft-tissue loss.
METHODS: Patients with a single failing tooth in the anterior maxilla (15-25) were treated at six centres. Following tooth extraction, they were randomly allocated to the test group (immediate implant placement, IIP) or control group (delayed implant placement, DIP). ARP was performed in both groups and implants were immediately restored with an implant-supported provisional crown. Six months after tooth extraction and ARP, a panel of five blinded clinicians assessed the need for STA on the basis of anonymized clinical pictures and a digital surface model. Lack of buccal soft-tissue convexity and/or mid-facial recession qualified for STA. Pre-operative and 6-month digital surface models were superimposed to assess horizontal and vertical soft-tissue changes.
RESULTS: Thirty patients were included per group (test: 20 females, 10 males, mean age 53.1; control: 15 females, 15 males, mean age 59.8). The panel deemed STA as necessary in 24.1% and 35.7% of the cases following IIP and DIP, respectively. The difference was not statistically significant (odds ratio [OR] = 1.77; 95% confidence interval [CI] [0.54-5.84]; p = .343). Loss of buccal soft-tissue profile was higher following DIP (estimated mean ratio = 1.66; 95% CI [1.10-2.52]; p = .018), as was mid-facial recession (mean difference [MD] = 0.47 mm; 95% CI [0.12-0.83]; p = .011). Besides DIP, regression analysis identified soft-tissue thickness (-0.57; 95% CI [-1.14 to -0.01]; p = .045) and buccal bone dehiscence (0.17; 95% CI [0.01-0.34]; p = .045) as additional risk factors for mid-facial recession. Surgeons found IIP significantly more difficult than DIP (visual analogue scale MD = -34.57; 95% CI [-48.79 to -20.36]; p < .001).
CONCLUSIONS: This multi-centre randomized controlled trial failed to demonstrate a significant difference in the need for STA between IIP and DIP when judged by a panel of blinded clinicians. Based on objective soft-tissue changes, patients with thin buccal soft tissues, with a buccal bone dehiscence and treated with a delayed approach appeared particularly prone to soft-tissue loss.

OBJECTIVE: This in vitro study aimed to assess the positional accuracy during the sequence of static computer-assisted implant surgery (sCAIS) according to the anatomical characteristics of the alveolar ridge.
METHODS: Maxillary bone models with six single tooth gaps including clinical scenarios of healed alveolar ridge (HR), single-rooted (SRS), and three-rooted socket (TRS) morphologies were used in this study. Positional deviations during implant placement procedures were evaluated after the pilot osteotomy (PD), final osteotomy (FD), and implant placement with respect to the pre-planned implant position by using a software package. ANOVA and post hoc analyses were performed.
RESULTS: A total of 90 implants were included in this study. Higher mean angular, crestal, and apical deviations were found after the PD and FD (3.5 ± 2.4°, 0.7 ± 0.3 mm, and 1.4 ± 0.8 mm versus 3.6 ±2.2°, 0.6 ± 0.3 mm, and 1.2 ± 0.6 mm) compared to IP (2.8 ± 1.6°, 0.7 ± 0.3 mm, and 1.2 ± 0.5 mm, p ≤ 0.004). Implants placed in TRS demonstrated higher mean angular, crestal, and apical deviations (4.0 ± 1.7°, 0.8 ± 0.3 mm, and 1.6 ± 0.5 mm) compared to implants placed in SRS (2.5 ± 1.2°, 0.7 ± 0.3 mm, and 1.1 ± 0.4 mm) or HR (2.0 ± 0.9°, 0.5 ± 0.3 mm, and 0.8 ± 0.4 mm, p < 0.001).
CONCLUSIONS: Positional deviations during sCAIS procedures are initiated with the first implant osteotomy and persist throughout the drilling sequence. However, deviations slightly decreased after implant placement. The alveolar ridge morphology is strongly associated with positional deviations. Higher deviations were observed in three-rooted and single-rooted sockets simulating an immediate approach compared to healed sites simulating a delayed protocol.

OBJECTIVE: This study aimed to histologically evaluate the healing at 8 weeks after coronally advanced flap (CAF) with either a superficial (SCTG) or deep palatal connective tissue graft (DCTG), or a collagen matrix (CM) to cover recession defects at teeth and implants.
METHODS: One mandibular side of 6 miniature pigs received each 3 titanium implants 12 weeks after extraction. Eight weeks later, recession defects were created around implants and contralateral premolars and 4 weeks later randomly subjected to CAF + SCTG, CAF + DCTG, or CAF + CM. After 8 weeks, block biopsies were histologically analyzed.
RESULTS: For the primary outcome, i.e., keratinization of the epithelium, all teeth and implants exhibited a keratinized epithelium with no histological differences among them also not in terms of statistically significant differences in length (SCTG 0.86 ± 0.92 mm, DCTG 1.13 ± 0.62 mm, and Cm, 1.44 ± 0.76 mm). Pocket formation was histologically seen at all teeth, around most implants with SCTG and DCTG, however not in the CM implant group. The connective tissue grafts showed hardly signs of degradation, whereas the CM was partly degraded and integrated in connective tissue. The mean gain in gingival height was similar in all experimental groups (SCTG 3.89 ± 0.80 mm, DCTG 4.01 ± 1.40 mm, CM 4.21 ± 0.64 mm). Statistically significant differences were found in the height of the junctional epithelium between the control teeth and the connective tissue groups (p = 0.009 and 0.044).
CONCLUSIONS: In this animal model, the use of either a superficial or deep connective tissue graft or a collagen membrane did not seem to have any impact on the epithelial keratinization around both teeth and implants. All procedures (CAF + SCTG/DCTG/CM) resulted in a long JE that was even longer at implants.
CONCLUSIONS: Deep/superficial palatal connective tissue graft yielded similar keratinization around teeth/implants. Given the absence of pocket formation and inflammatory processes at implants when using a CM, CAF + CM might bear potential clinical benefits.

(1) Aim: a cross-linked porcine-derived collagen matrix (CMX) has been developed for soft tissue augmentation. Although this grafting material does not require a second surgical site, recent findings have indicated deeper pockets, more marginal bone loss and more midfacial recession in the short term when compared to connective tissue graft (CTG). Hence, the aim of the present study was to evaluate the safety of CMX based on buccal bone loss over a one-year period. (2) Methods: Patients who were missing a single tooth in the anterior maxilla were included, in whom the failing tooth had been removed at least 3 months prior and who presented a horizontal mucosa defect. All sites had a bucco-palatal bone dimension of at least 6 mm as assessed on Cone-Beam Computed Tomography (CBCT) to ensure complete embedding of an implant by bone. All patients received a single implant and an immediate implant restoration using a full digital workflow. Sites were randomly allocated to the control (CTG) or test group (CMX) to increase buccal soft tissue thickness. All surgeries were performed by means of full thickness mucoperiosteal flap elevation, placing CTG and CMX in contact with the buccal bone wall. Safety was assessed by evaluating the impact of CTG and CMX on buccal bone loss over a one-year period using superimposed CBCT scans. (3) Results: thirty patients were included per group (control: 50% females, mean age 50; test: 53% females, mean age 48) and 51 (control: 25; test: 26) could be analyzed for buccal bone loss. At 1 mm apical to the implant-abutment interface (IAI), most horizontal resorption was found pointing to 0.44 mm in the control group and 0.59 mm in the test group. The difference of 0.14 mm (95% CI: -0.17-0.46) was not statistically significant (p = 0.366). At 3 mm and 5 mm apical to the IAI, the difference between the groups was 0.18 mm (95% CI: -0.05-0.40; p = 0.128) and 0.02 mm (95% CI: -0.24-0.28; p = 0.899), respectively. Vertical buccal bone loss amounted to 1.12 mm in the control group and 1.14 mm in the test group. The difference of 0.02 mm (95% CI: -0.53-0.49) was not statistically significant (p = 0.926). (4) Conclusions: In the short term, soft tissue augmentation with CTG or CMX results in limited buccal bone loss. CMX is a safe alternative to CTG. Longer follow-up is needed to assess the impact of soft tissue augmentation on buccal bone.

This in vitro study aimed at comparing the accuracy of freehand implant placement with static computer-assisted implant surgery (sCAIS), utilizing a keyless and a drill-key implant system and two guide-hole designs.
A total of 108 implants were placed in 18 partially edentulous maxillary models simulating two different alveolar ridge morphologies. 3D digital deviations between pre-planned and post-operative implant positions were obtained. Guide material reduction was assessed in the keyless implant system for the manufacturer\'s sleeve and sleeveless guide-hole designs.
sCAIS using a sleeveless guide-hole design demonstrated smaller mean angular, crestal and apical deviations compared to sCAIS utilizing a manufacturer\'s sleeve and the freehand group (2.6 ± 1.6°, vs 3.3 ± 1.9°, vs 4.0 ± 1.9°; 0.5 ± 0.3 mm, vs 0.6 ± 0.3 mm, vs 0.8 ± 0.3 mm; and 1.0 ± 0.5 mm, vs 1.2 ± 0.7 mm, vs 1.5 ± 0.6 mm). Smaller angular and apical mean deviations were observed in the keyless implant system as compared with the drill-key implant system (3.1 ± 1.7°, vs 3.5 ± 1.9°, p = 0.03; and 1.2 ± 0.6 mm, vs 1.4 ± 0.7 mm, p = 0.045). Overall, smaller angular, crestal, and apical deviations (p < 0.0001) were observed in healed alveolar ridges (2.4 ± 1.7°, 0.5 ± 0.3 mm, and 0.9 ± 0.5 mm) than in extraction sockets (4.2 ± 1.6°, 0.8 ± 0.3 mm, and 1.6 ± 0.5 mm). Higher mean volumetric material reduction was observed in sleeveless than in manufacturer\'s sleeve guide-holes (- 0.10 ± 0.15 mm3, vs - 0.03 ± 0.03 mm3, p = 0.006).
Higher final implant positional accuracy was observed in sCAIS for the keyless implant system, with a sleeveless guide-hole design, and in healed ridges. Sleeveless guide holes resulted in higher volumetric material reduction compared with the manufacturer\'s sleeve.

The primary aim of this in vitro study was to evaluate the influence of alveolar ridge morphologies on the accuracy of static Computer-Assisted Implant Surgery (sCAIS). The secondary aims were to evaluate the influence of guide-hole design and implant macro-design on the accuracy of the final implant position.
Eighteen standardized partially edentulous maxillary models with two different types of alveolar ridge morphologies were used. Each model was scanned via cone beam computer tomography prior to implant placement and scanned with a laboratory scanner prior to and following implant placement using sCAIS. The postsurgical scans were superimposed on the initial treatment planning position to measure the deviations between planned and postsurgical implant positions.
Seventy-two implants were equally distributed to the study groups. Implants placed in healed alveolar ridges showed significantly lower mean deviations at the crest (0.36 ± 0.17 mm), apex (0.69 ± 0.36 mm), and angular deviation (1.86 ± 0.99°), compared to implants placed in fresh extraction sites (0.80 ± 0.29 mm, 1.61 ± 0.59 mm, and 4.33 ± 1.87°; all p<0.0001). Implants placed with a sleeveless guide-hole design demonstrated significantly lower apical (1.02 ± 0.66 mm) and angular (2.72 ± 1.93°) deviations compared to those placed with manufacturer\'s sleeves (1.27 ± 0.67 mm; p = 0.01, and 3.46 ± 1.9°; p = 0.02). Deep-threaded tapered bone level implants exhibited significantly lower deviations at the crest (0.49 ± 0.28 mm), apex (0.97 ± 0.63 mm), and angular deviations (2.63 ± 1.85°) compared to shallow-threaded parallel-walled bone level implants (0.67 ± 0.34 mm; p = 0.0005, 1.32 ± 0.67 mm; p = 0.003, and 3.56 ± 1.93°; p = 0.01).
The accuracy of the final implant position with sCAIS is determined by the morphology of the alveolar ridge, the design of the guide holes, and the macrodesign of the implant.
Higher accuracy in the final implant position was observed with implants placed in healed alveolar ridge morphologies, in implants with deep-threaded tapered macro-design, and when sleeveless surgical guide holes were used.

OBJECTIVE: The objective of this study was to analyze the impact of the abutment width on early marginal bone loss (MBL).
METHODS: A balanced, randomized, double-blind clinical trial with two parallel experimental arms was conducted without a control group. The arms were \"cylindrical\" abutment and \"concave\" abutment. Eighty hexagonal internal connection implants, each with a diameter of 4 × 10 mm, were placed in healed mature bone. The main variable was the peri-implant tissue stability, which was measured as MBL at 8 weeks and 6 months.
RESULTS: The final sample consisted of 77 implants that were placed in 25 patients. 38 (49.4%) were placed using the cylindrical abutment, and the other 39 (50.6%) were placed using the concave abutment. The early global MBL of -0.6 ± 0.7 mm in the cylindrical abutment group was significantly higher than it was in the concave abutment group, in which the early global MBL was -0.4 ± 0.6 mm (p = .030). The estimated effect size (ES) was negative for the cylindrical abutment (ES = -1.3730, CI -2.5919 to -0.1327; t-value = -2.4893; p = .0139), therefore implying a loss of mean bone level, and it was positive for the concave abutment (ES = 2.8231; CI: 1.4379 to 4.2083; t-value = 4.0957; p = .0002), therefore implying an increase in the average bone level.
CONCLUSIONS: The concave abutments presented significantly less early MBL at 6 months post-loading than classical cylindrical abutments did.