Influence of drilling sequence and guide-hole design on the accuracy of static computer-assisted implant surgery in extraction sockets and healed sites-An in vitro investigation.

OBJECTIVES: To evaluate the effect of drilling sequence, guide-hole design, and alveolar ridge morphology on the accuracy of implant placement via static computer-assisted implant surgery (sCAIS). MATERIALS AND METHODS: Standardized maxillary bone models including single-tooth gaps with fresh extraction sockets or healed alveolar ridge morphologies were evaluated in this study. Implants were placed using different drilling sequences (i.e., complete [CDS] or minimum [MDS]), and guide-hole designs (i.e., manufacturer's sleeve [MS] or sleeveless [SL] guide-hole designs). The time for implant placement via sCAIS procedures was also recorded. The angular, crestal, and apical three-dimensional deviations between planned and final implant positions were digitally obtained. Statistical analyses were conducted by a non-parametric three-way ANOVA (α = .05). RESULTS: Based on a sample size analysis, a total of 72 implants were included in this study. Significantly higher implant position accuracy was found at healed sites compared to extraction sockets and in SL compared to MS guide-hole design in angular, crestal, and apical 3D deviations (p ≤ .048). A tendency for higher accuracy was observed for the CDS compared to the MDS, although the effect was not statistically significant (p = .09). The MDS required significantly shorter preparation times compared with CDS (p < .0001). CONCLUSION: Implant placement via sCAIS resulted in higher accuracy in healed sites than extraction sockets, when using SL compared to MS guides, and tended to be more accurate when using CDS compared to MDS. Therefore, even though surgery time was shorter with MDS, its use should be limited to strictly selected cases.

Group 1 ITI Consensus Report: The role of bone dimensions and soft tissue augmentation procedures on the stability of clinical, radiographic, and patient-reported outcomes of implant treatment.

OBJECTIVES: The aims of Working Group 1 were to address the role (i) of the buccolingual bone dimensions after implant placement in healed alveolar ridge sites on the occurrence of biologic and aesthetic complications, and (ii) of soft tissue augmentation (STA) on the stability of clinical, radiographic, and patient-related outcomes of implant treatments. MATERIALS AND METHODS: Two systematic reviews were prepared in advance of the Consensus Conference and were discussed among the participants of Group 1. Consensus statements, clinical recommendations, recommendations for future research, and reflections on patient perspectives were based on structured group discussions until consensus was reached among the entire group of experts. The statements were then presented and accepted following further discussion and modifications as required by the plenary. RESULTS: Dimensional changes of the alveolar ridge occurred after implant placement in healed sites, and a reduction in buccal bone wall thickness (BBW) of 0.3 to 1.8 mm was observed. In healed sites with a BBW of <1.5 mm after implant placement, increased vertical bone loss, and less favorable clinical and radiographic outcomes were demonstrated. Implants with buccal dehiscence defects undergoing simultaneous guided bone regeneration, showed less vertical bone loss, and more favorable clinical and radiographic outcomes, compared to non-augmented dehiscence defects during initial healing. At healthy single implant sites, probing depths, bleeding and plaque scores, and interproximal bone levels evaluated at 1 year, remained stable for up to 5 years, with or without STA. When single implant sites were augmented with connective tissue grafts, either for soft tissue phenotype modification or buccal soft tissue dehiscence, stable levels of the soft tissue margin, and stable or even increased soft tissue thickness and/or width of keratinized mucosa could be observed from 1 to 5 years. In contrast, non-augmented sites were more prone to show apical migration of the soft tissue margin in the long-term. Favorable aesthetic and patient-reported outcomes after STA were documented to be stable from 1 to 5 years. CONCLUSIONS: It is concluded that dimensional changes of the alveolar ridge occur after implant placement in healed sites and that sites with a thin BBW after implant placement are prone to exhibit less favorable clinical and radiographic outcomes. In addition, it is concluded that STA can provide stable clinical, radiographic, aesthetic, and patient-reported outcomes in the medium and long-term.

Local Concentrations of TGF-ß1 and IGF-1 Appear Determinant in Regulating Bone Regeneration in Human Postextraction Tooth Sockets.

Healing after tooth extraction involves a series of reparative processes affecting both alveolar bone and soft tissues. The aim of the present study was to investigate whether activation of molecular signals during the healing process confers a regenerative advantage to the extraction socket soft tissue (ESsT) at 8 weeks of healing. Compared to subepithelial connective tissue graft (CTG), qRT-PCR analyses revealed a dramatic enrichment of the ESsT in osteogenic differentiation markers. However, ESsT and CTG shared characteristics of nonspecialized soft connective tissue by expressing comparable levels of genes encoding abundant extracellular matrix (ECM) proteins. Genes encoding the transforming growth factor-ß1 (TGF-ß1) and its receptors were strongly enriched in the CTG, whereas the transcript for the insulin-like growth factor-1 (IGF-1) showed significantly high and comparable expression in both tissues. Mechanical stimulation, by the means of cyclic strain or matrix stiffness applied to primary ESsT cells (ESsT-C) and CTG fibroblasts (CTG-F) extracted from the tissue samples, revealed that stress-induced TGF-ß1 not exceeding 2.3 ng/mL, as measured by ELISA, in combination with IGF-1 up to 2.5 ng/mL was able to induce the osteogenic potential of ESsT-Cs. However, stiff matrices (50 kPa), upregulating the TGF-ß1 expression up to 6.6 ng/mL, caused downregulation of osteogenic gene expression in the ESsT-Cs. In CTG-Fs, endogenous or stress-induced TGF-ß1 ≥ 4.6 ng/mL was likely responsible for the complete lack of osteogenesis. Treatment of ESsT-Cs with TGF-ß1 and IGF-1 proved that, at specific concentrations, the two growth factors exhibited either an inductive-synergistic or a suppressive activity, thus determining the osteogenic and mineralization potential of ESsT-Cs. Taken together, our data strongly warrant the clinical exploration of ESsT as a graft in augmentative procedures during dental implant placement surgeries.

Positional accuracy during the sequence of static computer-assisted implant surgery in three alveolar ridge morphologies: An in vitro study.

PURPOSE: 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. MATERIAL AND 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.

Long-term effectiveness of 6 mm micro-rough implants in various indications: A 4.6- to 18.2-year retrospective study.

OBJECTIVES: To evaluate the long-term effectiveness of 6 mm implants in various indications with a micro-rough surface after 4.6-18.2 years in function and to assess key factors associated with implant survival, success, and biologic/technical complications. MATERIALS AND METHODS: Fifty-five patients with seventy-four 6 mm implants placed from 2000 to 2013 attended the re-examination assessing well-established clinical and radiographic parameters, biologic and prosthetic complications, and patient-reported outcome measures. RESULTS: Five implants were lost after a mean follow-up period of 9.1 years resulting in a survival rate of 93.2%. All losses occurred in free-end situations in the mandible. Smoking habit significantly reduced implant survival (hazard ratio 36.25). Two implants exhibited a history of peri-implantitis, and one implant showed progressive marginal bone loss (MBL) resulting in a success rate of 89.2%. The mean MBL amounted to 0.029 mm. Increased MBL was found for implants placed in the maxilla (0.057 mm) and for implants with a diameter of 4.1 mm (0.043 mm). Soft tissue thickness (1.39 mm) and width of keratinized mucosa (1.91 mm) had no effect on MBL. Patient-reported outcome measures showed high satisfaction (mean VAS scores 88%) and high quality of life (mean OHIP-G14 score 2.2). CONCLUSION: The present study demonstrated survival and success rates of 93.2% and 89.2% for 6 mm implants used in various indications. A factor leading to higher implant failure was smoking, whereas modulating factors increasing annual MBL included implants placed in the maxilla and implants with a diameter of 4.1 mm compared to 4.8 mm.

Cellular responses to deproteinized bovine bone mineral biofunctionalized with bone-conditioned medium.

OBJECTIVES: The aim of the study was to investigate whether the osteoinductive properties of bone-conditioned medium (BCM) harvested from cortical bone chips within a clinically relevant short-term period can enhance the biologic characteristics of deproteinized bovine bone mineral (DBBM) in vitro. MATERIALS AND METHODS: To assess the biofunctionalization of DBBM, the adhesive, proliferative, and differentiation properties of mesenchymal stromal ST2, pre-osteoblastic MC3T3-E1, and primary bone-derived cells grown on BCM-coated DBBM were examined by crystal violet staining of adherent cells, BrdU ELISA, and qRT-PCR, respectively. RESULTS: BCM extracted within 20 min or 24 h in either Ringer's solution (BCM-RS) or RS mixed with autologous serum (BCM-RS + S) increased the adhesive properties of all three cell types seeded on DBBM. The 20-min BCM-RS preparation appeared more potent than the 24-h preparation. BCM-RS made within 20 min or 24 h had strong pro-proliferative effects on all cell types grown on DBBM. RS + S alone exhibited a considerable pro-proliferative effect, suggesting an impact of the serum on cellular growth. DBBM coated with BCM-RS or BCM-RS + S, made within 20 min or 24 h each, caused a significant induction of osteogenic differentiation marker expression with a higher potency of the BCM-RS + S. Finally, a strong additive effect of fresh bone chips combined with BCM-coated DBBM on the osteogenic differentiation of the three cell types was observed. CONCLUSIONS: Altogether, the data strongly support the biofunctionalization of DBBM with BCM extracted within a clinically relevant time window of 20 min. CLINICAL RELEVANCE: Pre-activation of non-osteoinductive biomaterials with BCM, prepared from autologous bone chips during a guided bone regeneration (GBR) procedure, bears the potential of an optimal treatment modality for bone defects in daily practice.

Effects of local application of alendronate on early healing of extraction socket in dogs.

OBJECTIVE: The aim of the present study was to assess the effects of alendronate (ALN) on bone remodeling following tooth extraction in a dog model. MATERIAL AND METHODS: For the study, fifteen male Beagles dogs of approximately 12 months of age were used. Mesial roots of four mandibular premolars were endodontically treated, and the distal roots were removed. ALN concentrations of 0.5, 1, and 2 mg/mL were topically applied for 15 min, while a sterile saline was used as a negative control. After the healing period of 1, 2, and 8 weeks, the samples were analyzed by micro-CT and histology. RESULTS: Treatment with ALN increased vertical distance between the lingual and the buccal crestal bones. While the ALN-treated sockets had preserved more lingual bone areas, control sockets showed better preservation of the buccal bone areas. ALN treatment resulted in more osteoid formation within the extraction sockets compared with the control. Higher bone volume was found in ALN groups than in the control at 2-week and 8-week healing periods, reaching the significant difference only for the extraction sockets pooled for the ALN treatment. CONCLUSIONS: Although ALN treatment could not prevent buccal bone resorption following tooth extraction in dogs, it proved beneficial for the preservation of the lingual bone and formation of new bone within the socket. There was no clear relation between the ALN dosages and the alterations within the extraction sockets. CLINICAL RELEVANCE: ALN affects bone remodeling of the extraction socket. The optimal concentration remains to be determined in future studies.

Effectiveness and clinical performance of early implant placement for the replacement of single teeth in anterior areas: A systematic review.

AIM: To assess the effectiveness and clinical performance of early implant placement, 4-8 (Type 2) or 12-16 weeks (Type 3) after extraction, in single anterior sites. METHODS: Studies reporting on Type 2 and Type 3 implant placement were identified. Findings were summarized in evidence tables. Main outcome was implant survival. Peri-implant soft and hard tissues changes, periodontal parameters, aesthetics and patient-reported outcomes were also evaluated. Quality of reporting of the included studies was evaluated through Consort, Newcastle-Ottawa scale and IHE quality appraisal checklist. RESULTS: Nineteen eligible articles (seven from one RCT, three from two CCTs and nine from three case series) reporting on 140 patients and 140 implants were included. Type 3 implants showed comparable results to Type 4: 95% vs. 100% survival rates. Studies reported high values of implant survival, minimal technical and biological complications and high aesthetic scores in both short and long-term follow-ups for both Type 2 and Type 3 implant placement. Quality evaluation highlighted important weaknesses in the included trials. CONCLUSIONS: Limited data on Type 2 and Type 3 implant placement appear to indicate that they can perform well both short and long term. However, the limited number of cases, the significant heterogeneity of the included studies and the high risk of biases importantly reduce the generalizability of the findings. CRD42018117363.

Soft tissue response to dental implant closure caps made of either polyetheretherketone (PEEK) or titanium.

OBJECTIVE: Polyetheretherketone (PEEK) is a popular synthetic thermoplastic polymer for medical applications, but its clinical use suffers from several limitations. Therefore, the aim was to compare the soft tissue response to dental implant closure caps made of PEEK or titanium as evaluated by the occurrence of multinucleated giant cells (MNGCs). MATERIAL AND METHODS: Forty-two implants were placed in the maxilla of seven miniature pigs. While commercially pure titanium (Ti) implants had a Ti closure cap, ceramic implants made of either zirconia (Zr) or alumina-toughened zirconia (Zr + Al) received a PEEK closure cap. Histomorphometry was performed to evaluate the number of small and large MNGCs being in contact with the PEEK or the Ti in different compartments of the implant systems. RESULTS: No histological signs of inflammation were noticed, and MNGCs were observed on both PEEK and Ti closure caps and on all three implant types. Significantly higher numbers of MNGCs were found on closure caps made of PEEK than on closure caps made of Ti on the external closure cap surface facing both soft (p = 0.0008 for PEEK on Zr and p = 0.0016 for PEEK on Zr + Al) and hard tissues (p = 0.016 for PEEK on Zr and p = 0.003 for PEEK on Zr + Al) as well as in the internal closure cap surface (p = 0.014 for PEEK on Zr and p = 0.0088 for PEEK on Zr + Al). No statistically significant differences in the number of MNGCs were observed on the three implant types. CONCLUSIONS: Significantly more MNGCs were in contact with PEEK than with Ti closure caps.

Medication-related dental implant failure: Systematic review and meta-analysis.

OBJECTIVES: The aim of this systematic review was to investigate the association between the intake of systemic medications that may affect bone metabolism and their subsequent impact on implant failures. MATERIAL AND METHODS: Electronic and manual literature searches were conducted. Implant failure (IF) was the primary outcome, while biological/mechanical and the causes/timing associated with IF were set as secondary outcomes. Meta-analyses for the binary outcome IF and odds ratio were performed to investigate the association with medications. RESULTS: A final selection of 17 articles was screened for qualitative assessment. As such, five studies focused on evaluating the association of implant failure and non-steroidal anti-inflammatory drugs (NSAIDs), two on selective serotonin reuptake inhibitors (SSRIs), two on proton pump inhibitors (PPIs), seven on bisphosphonates (BPs), and one on anti-hypertensives (AHTNs). For PPIs, the fixed effect model estimated a difference of IF rates of 4.3%, indicating significantly higher IF rates in the test compared to the control group (p < 0.5). Likewise, for SSRIs, the IF was shown to be significantly higher in the individuals taking SSRIs (p < 0.5) as estimated a difference of 7.5%. No subset meta-analysis could be conducted for AHTNs medications as only one study fulfilled the inclusion criteria, which revealed an increased survival rate of AHTN medication. None of the other medications yielded significance. CONCLUSIONS: The present systematic review showed an association of PPIs and SSRIs with an increased implant failure rate. Hence, clinicians considering implant therapy should be aware of possible medication-related implant failures.

Diagnostic accuracy of the implant stability quotient in monitoring progressive peri-implant bone loss: An experimental study in dogs.

OBJECTIVES: To investigate the impact of progressive bone loss in an experimental peri-implantitis model in the dog upon the implant stability quotient (ISQ) measured in the course of induced and spontaneous conditions of disease, and to evaluate the association between the clinical parameters and ISQ. MATERIALS AND METHODS: Seventy-two implants were placed in 12 Beagle dogs. Of these, 36 implants in six dogs were assessed during ligature-induced peri-implantitis (three timepoints) and at one timepoint following a period of spontaneous progression. The ISQ was recorded using resonance frequency analysis (RFA). Furthermore, the clinical peri-implant parameters were registered at four sites per implant at each timepoint. Marginal bone loss (MBL) was determined using computed tomography at four sites per implant and bone-to-implant contact (BIC) was assessed from histological samples. A linear regression model was estimated by generalized estimation equations (GEEs) in order to study the MBL-ISQ values at each measurement timepoint. Pearson's correlation test was applied. RESULTS: None of the implants failed during the study period. At implant level, a strong negative correlation was found for all timepoints between ISQ and MBL (r = -0.58; p < 0.001). Accordingly, as follow-up progressed, lower ISQ and higher MBL values were observed. A prediction of MBL depending on the ISQ values and timepoints showed a decrease in one ISQ unit to be related to ~1 mm of MBL. Likewise, a statistically significant correlation was found between BIC and ISQ evaluated after spontaneous chronification of peri-implantitis (r = 0.34; p = 0.04). Nevertheless, the ISQ values failed to correlate to any of the clinical parameters recorded. CONCLUSION: Resonance frequency analysis seems accurate in diagnosing progressive bone loss, as a statistically significant decrease in ISQ was recorded in the course of peri-implant disease. Nevertheless, the clinical relevance of this observation as a diagnostic tool is debatable, since implant stability remains high.

Group 1 ITI Consensus Report: The influence of implant length and design and medications on clinical and patient-reported outcomes.

OBJECTIVES: The aim of Working Group 1 was to address the influence of different local (implant length, diameter, and design) and systemic (medications) factors on clinical, radiographic, and patient-reported outcomes in implant dentistry. Focused questions on (a) short posterior dental implants (≤6 mm), (b) narrow diameter implants, (c) implant design (tapered compared to a non-tapered implant design), and (d) medication-related dental implant failures were addressed. MATERIALS AND METHODS: Four systematic reviews were prepared in advance of the Consensus Conference and were discussed among the participants of Group 1. Consensus statements, clinical recommendations, and recommendations for future research were based on structured group discussions until consensus was reached among the entire expert Group 1. The statements were then presented and accepted following further discussion and modifications as required by the plenary. RESULTS: Short implants (≤6 mm) revealed a survival rate ranging from 86.7% to 100%, whereas standard implant survival rate ranged from 95% to 100% with a follow-up from 1 to 5 years. Short implants demonstrated a higher variability and a higher Risk Ratio [RR: 1.24 (95% CI: 0.63, 2.44, p = 0.54)] for failure compared to standard implants. Narrow diameter implants (NDI) have been classified into three categories: Category 1: Implants with a diameter of <2.5 mm ("Mini-implants"); Category 2: Implants with a diameter of 2.5 mm to <3.3 mm; Category 3: Implants with a diameter of 3.3 mm to 3.5 mm. Mean survival rates were 94.7 ± 5%, 97.3 ± 5% and 97.7 ± 2.3% for category 1, 2 and 3. Tapered versus non-tapered implants demonstrated only insignificant differences regarding clinical, radiographic, and patient-reported outcomes. The intake of certain selective serotonin reuptake inhibitors and proton pump inhibitors is associated with a statistically significant increased implant failure rate. The intake of bisphosphonates related to the treatment of osteoporosis was not associated with an increased implant failure rate. CONCLUSIONS: It is concluded that short implants (≤6 mm) are a valid option in situations of reduced bone height to avoid possible morbidity associated with augmentation procedures; however, they reveal a higher variability and lower predictability in survival rates. Narrow diameter implants with diameters of 2.5 mm and more demonstrated no difference in implant survival rates compared to standard diameter implants. In contrast, it is concluded that narrow diameter implants with diameters of less than 2.5 mm exhibited lower survival rates compared to standard diameter implants. It is further concluded that there are no differences between tapered versus non-tapered dental implants. Certain medications such as selective serotonin reuptake inhibitors and proton pump inhibitors showed an association with a higher implant failure rate.

Osseointegration of titanium, titanium alloy and zirconia dental implants: current knowledge and open questions.

Bone healing around dental implants follows the pattern and sequence of intramembraneous osteogenesis with formation of woven bone first of all followed later by formation of parallel-fibered and lamellar bone. Bone apposition onto the implant surface starts earlier in trabecular bone than in compact bone. While the first new bone may be found on the implant surface around 1 week after installation, bone remodeling starts at between 6 and 12 weeks and continues throughout life. Bone remodeling also involves the bone-implant interface, thus transiently exposing portions of the implant surface. Surface modifications creating micro-rough implant surfaces accelerate the osseointegration process of titanium implants, as demonstrated in numerous animal experiments. Sandblasting followed by acid-etching may currently be regarded as the gold standard technique to create micro-rough surfaces. Chemical surface modifications, resulting in higher hydrophilicity, further increase the speed of osseointegration of titanium and titanium-zirconium implants in both animals and humans. Surface modifications of zirconia and alumina-toughened zirconia implants also have an influence on the speed of osseointegration, and some implant types reach high bone-to-implant contact values in animals. Although often discussed independently of each other, surface characteristics, such as topography and chemistry, are virtually inseparable. Contemporary, well-documented implant systems with micro-rough implant surfaces, placed by properly trained and experienced clinicians, demonstrate high long-term survival rates. Nevertheless, implant failures do occur. A low percentage of implants are diagnosed with peri-implantitis after 10 years in function. In addition, a low number of implants seem to be lost for primarily reasons other than biofilm-induced infection. Patient factors, such as medications interfering with the immune system and bone cells, may be an element contributing to continuous bone loss and should therefore be monitored and studied in greater detail.

Clinical relevance of dimensional bone and soft tissue alterations post-extraction in esthetic sites.

The key to achieving pleasing esthetics in implant dentistry is a thorough understanding of the biological processes driving dimensional bone and soft tissue alterations post-extraction. The aim of the present report is first to characterize the extent of bone and soft tissue changes post-extraction and second to identify potential factors influencing tissue preservation in order to facilitate successful treatment outcomes. The facial bone wall thickness has been identified as the most critical factor influencing bone resorption and can be used as a prognostic tool in order to identify sites at risk for future facial bone loss subsequent to tooth extraction. Clinical studies indicated that thin bone wall phenotypes exhibiting a facial bone wall thickness of 1 mm or less revealed progressive bone resorption with a vertical loss of 7.5 mm, whereas thick bone wall phenotypes showed only minor bone resorption with a vertical loss of 1.1 mm. This is in contrast to the dimensional soft tissue alterations. Thin bone wall phenotypes revealed a spontaneous soft tissue thickening after flapless extraction by a factor of seven, whereas thick bone wall phenotypes showed no significant changes in the soft tissue dimensions after 8 weeks of healing. In sites exhibiting a limited bone resorption rate, immediate implant placement may be considered. If such ideal conditions are not present, other timing protocols are recommended to achieve predictable and pleasing esthetics. Socket preservation techniques for ridge preservation utilizing different biomaterials and/or barrier membranes often result in a better maintenance of tissue volumes, although the inevitable biological process of post-extraction bone resorption and bone modeling cannot be arrested. In summary, the knowledge of the biological events driving dimensional tissue alterations post-extraction should be integrated into the comprehensive treatment plan in order to limit tissue loss and to maximize esthetic outcomes.

Coverage of mucosal recessions at dental implants.

Facial peri-implant mucosal recessions represent an increasing complication in implant dentistry and may negatively affect the esthetic outcome and patient satisfaction. The aim of the present paper is to provide a review on the potential causes of facial peri-implant mucosal recessions and to provide a rationale for treatment along with possible treatment options. The available data indicate that soft tissue augmentation around dental implants is possible, but at present there is no evidence demonstrating that the augmented soft tissues are able to influence the peri-implant bone levels (e.g. to limit peri-implant bone loss). Therefore, the rationale to cover or correct peri-implant mucosal recessions are (i) to optimize the possibility for performing an adequate level of oral hygiene, and (ii) to improve esthetics. At present, there is very limited evidence supporting any specific treatment modality for covering peri-implant soft tissue recessions. The limited available data indicate that only shallow peri-implant mucosal recessions (e.g. up to 2 mm) may be treated successfully by means of a coronally advanced flap and subepithelial connective tissue graft or with guided bone regeneration, while no data are available supporting the possibility of covering deep and large peri-implant mucosal recessions.

Implant placement post extraction in esthetic single tooth sites: when immediate, when early, when late?

Implant placement in post-extraction sites of single teeth in the esthetic zone has been a topic of great interest in the field of implant dentistry since 1990. Triggered by the development of guided bone regeneration, the concept of immediate implant placement became quite popular in the 1990s. In the past 12 years, however, the dental community has begun to focus increasingly on the esthetic outcomes of post-extraction implant placement and several studies indicated a significant risk for the development of mucosal recessions with immediate implants. Parallel with this, significant progress has been made in the understanding of tissue biology in terms of hard and soft tissue alterations post extraction, based on preclinical, clinical and radiological studies. This knowledge has helped better to understand the etiology of these esthetic complications with immediate implant placement. The present review first analyzes the various phases of the development of therapeutic strategies over the years for post-extraction implant placement in single tooth sites in the esthetic zone. It presents the current knowledge concerning the terminology with immediate, early and late implant placement, the risk factors for the development of esthetic complications, and the selection criteria for the various treatment options. In the second part, clinical recommendations are given, since a clinician active in this field of implant therapy can use all treatment options depending on the preoperative analysis including a 3D cone beam computed tomography. The selection criteria for all four treatment options are presented and documented with typical case reports to illustrate the current treatment approaches applied in daily practice.

Development of Implant Stability Quotient values of implants placed with simultaneous sinus floor elevation - results of a prospective study with 109 implants.

OBJECTIVES: In patients with implant placement and simultaneous sinus floor elevation (SFE), healing periods of 6 months have been the standard of care for more than 25 years. The primary objective of this prospective case series study was to determine what percentage of implants placed with SFE reach a threshold Implant Stability Quotient (ISQ) of ≥70 after 8 weeks of healing using Resonance Frequency Analysis (RFA). MATERIAL AND METHODS: A total of 109 dental implants were placed in 97 patients. SFE was carried out with a lateral window approach and a mixture of autogenous bone chips and deproteinized bovine bone mineral (DBBM). Titanium screw-type, tissue-level implants with a chemically modified SLA surface were used. ISQ values were measured after implant insertion (ISQBL ) and after 8 weeks of healing (ISQ8 wk ). Patients showing ISQ8 wk  ≥ 70 subsequently underwent restoration. Implants with an ISQ value < 70 were recalled at 2-week intervals. RESULTS: The ISQ at baseline had a mean value of 68.3 (SD ± 9.8). At 8 weeks, the mean ISQ value was 73.6 (SD ± 6.4). This increase was statistically significant (P < 0.001). An ISQ8 wk value ≥70 was observed for 91 implants (83%). One implant (0.9%) with a peri-implant infection and severe bone loss at 8 weeks was considered an early failure. CONCLUSIONS: This study showed that 83% of implants reached the threshold level of ISQ ≥ 70 after 8 weeks, allowing an early loading protocol. The early failure rate was considered low with 0.9%. The RFA technology is a suitable method to objectively monitor implant stability longitudinally.

The influence of collagen membrane and autogenous bone chips on bone augmentation in the anterior maxilla: a preclinical study.

OBJECTIVES: To evaluate the effect of a resorbable collagen membrane and autogenous bone chips combined with deproteinized bovine bone mineral (DBBM) on the healing of buccal dehiscence-type defects. MATERIAL AND METHODS: The second incisors and the first premolars were extracted in the maxilla of eight mongrels. Reduced diameter, bone-level implants were placed 5 weeks later. Standardized buccal dehiscence-type defects were created and grafted at implant surgery. According to an allocation algorithm, the graft composition of each of the four maxillary sites was DBBM + membrane (group D + M), autogenous bone chips + DBBM + membrane (group A + D + M), DBBM alone (group D) or autogenous bone chips + DBBM (group A + D). Four animals were sacrificed after 3 weeks of healing and four animals after 12 weeks. Histological and histomorphometric analyses were performed on oro-facial sections. RESULTS: The pattern of bone formation and resorption within the grafted area showed high variability among the same group and healing time. The histomorphometric analysis of the 3-week specimens showed a positive effect of autogenous bone chips on both implant osseointegration and bone formation into the grafted region (P < 0.05). The presence of the collagen membrane correlated with greater bone formation around the DBBM particles and greater bone formation in the grafted region after 12 weeks of healing (P < 0.05). The oro-facial width of the augmented region at the level of the implant shoulder was significantly reduced in cases where damage of the protection splints occurred in the first week of healing (P < 0.05). CONCLUSIONS: The addition of autogenous bone chips and the presence of the collagen membrane increased bone formation around DBBM particles. Wound protection from mechanical noxa during early healing may be critical for bone formation within the grafted area.

Effects of platelet rich plasma (PRP) on human gingival fibroblast, osteoblast and periodontal ligament cell behaviour.

BACKGROUND: The use of platelet rich plasma (PRP, GLO) has been used as an adjunct to various regenerative dental procedures. The aim of the present study was to characterize the influence of PRP on human gingival fibroblasts, periodontal ligament (PDL) cells and osteoblast cell behavior in vitro. METHODS: Human gingival fibroblasts, PDL cells and osteoblasts were cultured with conditioned media from PRP and investigated for cell migration, proliferation and collagen1 (COL1) immunostaining. Furthermore, gingival fibroblasts were tested for genes encoding TGF-ß, PDGF and COL1a whereas PDL cells and osteoblasts were additionally tested for alkaline phosphatase (ALP) activity, alizarin red staining and mRNA levels of osteoblast differentiation markers including Runx2, COL1a2, ALP and osteocalcin (OCN). RESULTS: It was first found that PRP significantly increased cell migration of all cells up to 4 fold. Furthermore, PRP increased cell proliferation at 3 and 5 days of gingival fibroblasts, and at 3 days for PDL cells, whereas no effect was observed on osteoblasts. Gingival fibroblasts cultured with PRP increased TGF-ß, PDGF-B and COL1 mRNA levels at 7 days and further increased over 3-fold COL1 staining at 14 days. PDL cells cultured with PRP increased Runx2 mRNA levels but significantly down-regulated OCN mRNA levels at 3 days. No differences in COL1 staining or ALP staining were observed in PDL cells. Furthermore, PRP decreased mineralization of PDL cells at 14 days post seeding as assessed by alizarin red staining. In osteoblasts, PRP increased COL1 staining at 14 days, increased COL1 and ALP at 3 days, as well as increased ALP staining at 14 days. No significant differences were observed for alizarin red staining of osteoblasts following culture with PRP. CONCLUSIONS: The results demonstrate that PRP promoted gingival fibroblast migration, proliferation and mRNA expression of pro-wound healing molecules. While PRP induced PDL cells and osteoblast migration and proliferation, it tended to have little to no effect on osteoblast differentiation. Therefore, while the effects seem to favor soft tissue regeneration, the additional effects of PRP on hard tissue formation of PDL cells and osteoblasts could not be fully confirmed in the present in vitro culture system.

Influence of implant neck design on facial bone crest dimensions in the esthetic zone analyzed by cone beam CT: a comparative study with a 5-to-9-year follow-up.

AIM: To examine the influence of two different neck designs on facial bone crest dimensions in esthetic single implant sites after a 5-to-9-year follow-up analyzed by cone beam computed tomography (CBCT). MATERIALS AND METHODS: Sixty-one patients with an implant-borne single crown following early implant placement in the esthetic zone were enrolled. The test group consisted of a bone level (BL) neck design exhibiting a hydrophilic micro-rough surface combined with a platform-switching interface (PS) (n = 20). The control group comprised a soft tissue level (STL) neck design exhibiting a hydrophobic machined surface with a matching butt-joint interface (n = 41). Standardized clinical, radiologic, and esthetic parameters were applied. The facial bone crest dimensions were assessed by CBCT. RESULTS: Soft tissue parameters and pink esthetic scores yielded no significant differences between the two designs. Major differences were only observed at the implant shoulder level. The height of the facial bone crest for the BL design was located 0.2 mm above the implant shoulder level, whereas for the STL design, its location was 1.6 mm below. The width of the peri-implant saucer-like bone defect was reduced by 40% for the BL implant design. No differences were observed 2 mm below the shoulder level. CONCLUSIONS: The results of this comparative study suggest better crestal bone stability on the facial aspect of single implant sites in the esthetic zone for a BL design with a platform-switching concept when compared with STL implants with a butt-joint interface.