Influence of cortical bone thickness and implant length on implant stability at the time of surgery--clinical, prospective, biomechanical, and imaging study

Analysis of changes in bone mineral density and cortical bone thickness after reconstruction of the mandible with fibula, is condyle preservation a critical influence factor?

OBJECTIVE

This study aimed to investigate the features of bone mineral density (BMD) and cortical bone thickness in grafted fibula.

MATERIALS AND METHODS

Eighty-six patients who underwent mandibular reconstruction using vascularized fibula flaps were enrolled, all of whom were followed up at 3, 6, and 12 months after surgery. The patients were grouped according to whether the condyle was preserved. BMD and cortical bone thickness were also measured.

RESULTS

Condyle-preserved group consisted of 65 patients and condyle-unpreserved group consisted of 21 patients. There was a significant correlation between thickness and BMD, which was significantly correlated with follow-up time. One year after surgery, the BMD of the condyle-preserved group decreased from 1029.61 ± 156.01 mg/cm3 to 978.6 ± 141.90 mg/cm3, and thickness decreased from 3.29 ± 0.65 mm to 2.72 ± 0.72 mm. BMD of the condyle-unpreserved group decreased from 1062.21 ± 126.01 mg/cm3 to 851.26 ± 144.38 mg/cm3, and thickness decreased from 3.46 ± 0.89 mm to 2.56 ± 0.73 mm. In the condyle-preserved and unpreserved groups, the absorption rates of BMD were 3.29 ± 11.97% and 17.09 ± 12.42% at 12 months, respectively, and the rate of thickness was 20.7 ± 11.45% and 26.39 ± 12.23% at 12 months, respectively.

CONCLUSION

BMD and thickness showed a decreasing trend over time. Preserving the condyle can slow bone resorption of the fibula. Regarding implant restoration, we recommend doctors to perform the treatment within 6-12 months after surgery in order to effectively manage bone resorption.

CLINICAL RELEVANCE

Our study found that condylar preservation can decrease the absorption rate of BMD and cortical bone thickness, helping doctors make better clinical decisions.

TRIAL REGISTRATION NUMBER

ChiCTR2300069661 (March 22, 2023).

Clinical evaluation of bone quality of particulate cancellous bone and marrow, and implant prosthetic rehabilitation

This study aimed to subjectively evaluate bone quality in the particulate cancellous bone and marrow (PCBM) graft area and to assess the survival rates of implants. A retrospective review was conducted based on patient age, sex, diagnosis, reconstructed site, number of implants, prosthetic type, and duration of follow-up. Images from computed tomography (CT) before implant insertion were obtained and used in this study. We selected a 4.0-mm diameter × 8.0-mm length region of interest in the implant placement area, and measured the CT attenuation value. No significant correlations were seen between CT attenuation values and implant survival rates in the maxilla and mandible. On the other hand, CT attenuation values and implant survival rates were significantly lower in patients with malignancy than in non-malignant cases. Placing implants in PCBM grafted bone requires a full understanding of bone quality before surgery and drilling to ensure primary stability, along with consideration of soft tissue management and maintenance programs.

Correlation between Implant Surface Roughness and Implant Stability: A Systematic Review

The aim of this study was to find in the literature data on the relationship between implant surface roughness and implant stability achieved, from the time of placement to three months afterward, to help us to know what type of surface roughness is more favorable to guarantee implant stability and osseointegration. A systematic review was conducted in accordance with the PRISMA 2020 (Preferred Reporting Items for Systematic Review and Meta-analysis) statement, and the protocol was registered on the Open Science Framework. The specific inclusion and exclusion criteria were selected using the PICOS framework. The databases Medline (PubMed), Scopus, the Web of Science and The Cochrane Library were searched up to October 2023. The selection of studies and data extraction were conducted by two independent reviewers. The review included a total of 11 studies. A total of 1331 dental implant placements were identified. Two of the eleven selected studies were on humans in vivo, eight were on animals in vivo, and one was on animals in vitro. A statistically significant correlation between surface roughness and implant stability as measured by resonance frequency analysis (RFA) was not identified in ten of the eleven selected studies. It appears that there is no correlation between primary stability and the degree of implant roughness. However, there appears to be a correlation between the roughness of the implant and the degree of osseointegration, as indicated by bone-implant contact values. This correlation is more closely related to secondary stability. The great methodological variability makes it difficult to compare data and draw conclusions, so it would be desirable to agree on a common methodology to help draw appropriate conclusions from published studies.

The Value of Mandibular Indices on Cone Beam Computed Tomography in Secondary Causes of Low Bone Mass

Background: As implant treatment cases increase, many cases of failure/side effects also occur. Generally, dental clinics determine the density of the jawbone using cone beam CT (CBCT). Considering the known potential role of this tool for bone assessment in primary osteoporosis, this study evaluated patients with secondary endocrine causes of low bone mass. Methods: The study included 83 patients with endocrine causes of osteoporosis who were evaluated by dual-energy X-ray absorptiometry (DXA), trabecular bone score (TBS), and mental foramen (MF) region CBCT. The following CBCT indices were measured: anterior (A)-thickness of inferior mandibular cortex 10 mm anterior from MF; molar (M)-thickness of inferior mandibular cortex 10 mm posterior from MF; posterior (P)-thickness of inferior mandibular cortex 25 mm posterior from MF; symphysis (S)-thickness of inferior mandibular cortex equidistant from the centers of right and left MF. Results: The highest correlation coefficient in the secondary causes group was between the A index and the lumbar BMD (r = 0.375, p = 0.001) and the P index and the femoral neck BMD (r = 0.38, p = 0.001). Hypercortisolism seems to be the most predictable cause of secondary osteoporosis using the A, M, and P indices. The A, M, and P indices showed predictive values of the bone micro-architecture that was evaluated using TBS score, and were statistically significant. The symphysis index does not significantly predict osteoporosis or impaired bone micro-architecture. Conclusions: These findings support the potential usefulness of A, M, and P CBCT-derived radiomorphometric mandibular indices in secondary osteoporosis, underlining the well-known effects of these pathologies on bone micro-architecture rather than bone quantity.

A study on the morphology of iliac crest based on the objectives of jaw bone defect reconstruction

OBJECTIVES

to understand the morphological characteristics of iliac crest and provide advice and assistance for jaw bone reconstruction with iliac bone flap by evaluating the thickness and curvature of iliac crest.

MATERIALS AND METHODS

100 patients who had taken Spiral CT of the Abdominal region before surgeries between 2020 and 2022 were included in this study. 3D reconstruction images of the iliac bones were created. 5 vertical planes perpendicular to the iliac crest were made every 2 cm along the centerline of the iliac crest (VP2 ~ VP10). On these vertical planes, 4 perpendicular lines were made every 1 cm along the long axis of the iliac crest (D1 ~ D4). The thicknesses at these sites, horizontal angle (HA) of iliac crest and the distance between inflection point and the central point of anterior superior iliac spine (DIA) were measured.

RESULTS

The thickness of iliac bone decreased significantly from D1 ~ D4 on VP6 ~ VP10 and from VP2 ~ VP10 on D3 and D4 level (P<0.05). HA of iliac crests was 149.13 ± 6.92°, and DIA was 7.36 ± 1.01 cm. Iliac bone thickness, HA and DIA had very weak or weak correlation with patient's age, height and weight.

CONCLUSIONS

The average thicknesses of iliac crest were decreased approximately from front to back, from top to bottom. The thickness and curvature of the iliac crest were difficult to predict by age, height and weight.

CLINICAL RELEVANCE

Virtual surgical planning is recommended before jaw bone reconstruction surgery with iliac bone flap, and iliac crest process towards alveolar process might be a better choice.

Influence of implant length and insertion depth on primary stability of short dental implants: An in vitro study of a novel mandibular artificial bone model

Background/purpose

Dental implants are a mainstream solution for missing teeth. For the improvement of dental implant surface treatment and design, short dental implants have become an alternative to various complex bone augmentation procedures, especially those performed at the posterior region of both the maxilla and mandible. The objective of this study was to evaluate the effect of various insertion methods on the primary stability of short dental implants.

Materials and methods

Commercial dental implants were inserted into artificial mandibular bone specimens using various insertion methods (equicrestal position, subcrestal position 1.5 mm, and lateral cortical anchorage) in accordance with an implant surgical guide. Insertion torque value (ITV) curves were recorded while implant procedures were performed. Both maximum ITVs (MITVs) and final ITVs (FITVs) were evaluated. Subsequently, Periotest values (PTVs) and implant stability quotients (ISQs) were measured for all specimens. A Kruskal-Wallis test was conducted to analyze the results for four primary stability parameters, and the Dunn test was used for a post hoc pairwise comparison when a difference was identified.

Results

For all groups, their mean MITVs ranged from 33.6 to 59.4 N cm, whereas their mean FITVs ranged from 17.5 to 43.5 N cm. Insertion torque value, ISQ, and PTV decreased significantly when implants were inserted into subcrestal positions. When implants were inserted in the lateral bicortical position, the four aforementioned parameters yielded greater values.

Conclusion

When 6-mm short implants were inserted in a lateral cortical anchorage position, high primary stability was yielded.

Radiographic alveolar bone assessment in correlation with primary implant stability: A systematic review and meta-analysis

INTRODUCTION

The radiographic examination of alveolar bone using 3D radiographic examination is essential in dental implant treatment planning. Our study aimed to systematically review and quantitatively analyze the correlation between alveolar bone parameters, specifically bone density and cortical bone thickness, assessed using cone beam computed tomography (CBCT) and/or multidetector computed tomography (MDCT); and primary implant stability (PIS) determined using implant stability quotient (ISQ), Periotest® value (PTV), and insertion torque value (ITV).

METHODS

This review was registered in the PROSPERO database (registration number CRD42022307245). An electronic literature search was conducted on the PubMed, SCOPUS, and Web of Science databases for papers published until February 2022. The Quality Assessment in Prognostic Studies (QUIPS) tool was used to assess risk of bias. Meta-analyses were conducted to calculate the estimated average correlation coefficient based on a multilevel random-effects model, followed by subgroup analysis.

RESULTS

Twenty-six studies were included in this review, consisting of 17 prospective cohort studies, eight retrospective cohort studies, and one nonrandomized controlled trial. A total of 3109 implants placed in 1171 subjects were analyzed. Twenty-three studies were evaluated using meta-analysis. The alveolar bone condition was significantly correlated with ISQ (r = 0.60; p < .001), IT (r = 0.52; p < .001), and PTV (r = -0.42; p < .05).

CONCLUSION

Alveolar bone condition is significantly associated with PIS. Low bone density and thin cortical bone can lead to low PIS; therefore, modification of treatment planning and surgical procedures might be needed to avoid poor osseointegration.

Immediate versus conventional loading of mandibular implant-retained overdentures: a 3-year follow-up of a randomized controlled trial

OBJECTIVES

There is a scarcity of randomized clinical trials (RCT) that report medium- and long-term results and a lack of consensus in the literature on the predictability of immediately loaded unsplinted narrow diameter implants supporting mandibular overdentures. This RCT compared the performance of conventional (CL) and immediate loading (IL) of mandibular overdentures retained by two narrow-diameter implants for 3 years.

MATERIALS AND METHODS

Patients from an RCT treated with CL or IL were invited to attend to 2- and 3-year follow-ups. Clinical, radiographic, functional, and oral health-related quality of life parameters were evaluated. Prosthetic maintenance events, biological complications, and success and survival rates were also recorded. The data were tested by multilevel mixed-effects linear regression analysis and chi-squared tests.

RESULTS

The 1-year survival rates of 90% in the CL group and 85% in the IL group were maintained as no implants were lost between 1 and 3 years. The marginal bone loss (MBL) in the IL group was significantly lower after year 3 (-0.04; p < 0.01). Significant changes were found only for the intra-group comparisons in the third year of function: (i) CL and IL presented similar progression of implant stability, MBL, and posterior bone area resorption; (ii) while CL started deteriorating of masticatory function, IL still exhibited functional evolution and (iii) oral comfort domain in the CL and pain domain in the IL were improved.

CONCLUSION

Although IL experienced the lowest MBL after 3 years, the outcomes showed that both loading protocols result in predictable medium-term rehabilitation when monitored annually.

CLINICAL RELEVANCE

It can be expected that in the third year of function, patients with immediate loading may present more complaints related to general performance even with acceptable masticatory function and self-reported improvements in oral comfort.

Specific use of the implant stability quotient as a guide to improve healing for patients who had undergone rehabilitation with fixed implant-supported dental prostheses

PURPOSES

to develop a clinical approach to evaluating osteointegration around bone implants and try to determining which was the correct time of implant loading in different edentulous indications, that is, either properly positioned implants or implants "at risk", generally referred to as implants having increased probability of failure (namely those for which primary stability had been achieved via a time-consuming surgery).

MATERIALS

Several implant-supported rehabilitation strategies, with or without bone augmentation procedures, were performed in the upper and lower arches: From 2 to 5 months following implant placement, the prosthetic restorations were performed. A resonance frequency analyzer allowed clinicians to measure intraoperative and postoperative implant stability, then the values of the implant stability quotient, ISQ, ranging from 0 to 100, were registered. ISQs were ranked into 3 levels: Green (ISQ ≥ 70), Yellow (60 ≤ ISQ < 70), and Red (ISQ < 60). Groups were subjected to Pearson's χ2 analysis, with YATES correction when necessary, with a significance level of 0.05.

RESULTS

A total of 213 implants had been included. When the distribution of normalized values of ISQ registered for implants inserted in native bone and loaded at 2-3 months (5 Red, 19 Yellow, and 51 Green) was compared to that of native implants loaded after 4-5 months (4 Red, 20 Yellow, and 11 Green), a significative difference was found (p-value = 0.0037). At the time of loading, significance was lost. Significant clinical improvements on the distribution of normalized values of ISQ were apparent for both the implants placed in pristine and those placed in lifted sinuses; no significant differences were registered between the two groups.

CONCLUSION

At the loading time, implants considered to be at risk behaved similarly to the native sites for which the overall prosthetic workflow took about few; results confirmed that the mandibular implants appeared to have higher stabilities when compared to maxillary implants at both the intraoperative and the postoperative surveys.

Feasibility analysis of bone density evaluation with Hounsfield unit value after fibula flap reconstruction of jaw defect

BACKGROUND

Implant-supported dentures have become an essential means of restoring occlusal function after jaw reconstruction. Bone mineral density (BMD) may influence the success rate of implant denture restorations. This study aimed to explore whether the Hounsfield unit (HU) value can be used to monitor the changing trend of fibular BMD after jaw reconstruction.

RESULTS

A total of 54 patients who underwent maxillar/mandibular reconstruction with a fibula flap were included in this study. There was a significant correlation between the HU value and BMD at 1 week, 3 months, and 6 months after surgery, and both were significantly correlated with follow-up time. The difference between each pair of absorption rates (DAR) was less than 10% in 66.7% and 75.9% of patients at 3 and 6 months; however, the DAR was more than 20% in 12% and 13.8% of patients at 3 and 6 months, respectively.

CONCLUSIONS

There is a significant correlation between HU value and BMD. The HU value can be used to roughly reflect the fibular BMD changing trend in a group of patients as opposed to an individual, and the HU value is not equivalent to BMD.

TRIAL REGISTRATION

ChiCTR, ChiCTR2300069661, retrospectively registered on 22 March 2023. Retrospectively registered, https://www.chictr.org.cn/showproj.html?proj=188953 .

Clinical Evaluation of Short (6 mm) and Longer Implants Placed Side by Side in Posterior Partially Edentulous Area: A 3-Year Observational Study

Background

Short implants have been proposed as an alternative solution for the rehabilitation of atrophic posterior region.

Purpose

To compare the clinical outcomes between 6 mm short implants and conventional implants placed under similar conditions of bone quality and occlusal loading.

Materials and Methods

Nine patients received atone 6 mm implant and one standard-length (8 mm length or longer) implants in a total of 10 partially edentulous areas. Implants were left submerged for 3-6 months healing period and the screw-retained splinted prostheses were delivered. When the provisional or final restoration was placed, and at each year after loading, standardized intraoral radiograph was taken for themarginal bone level (MBL) changes around the implants. Subsequently, the patients were recalled for the clinical examination evaluating the implant survival, sulcus bleeding index, suppuration, and the incidence of prosthetic complications at every 6 months after the definitive crown delivery. The observation period was continued to 3 years (mean follow-up was 3.4 ± 0.3 years) after functional loading.

Results

Nine patients (10 short implants and 10 standard length implants) were selected in this study. Cumulative survival rates of the short implants and standard-length implants were 100% in both groups, and no biological and prosthetic complication were found in 3 years observation period. Cortical bone thickness of implant insertion sites was 1.39 ± 0.45 mm at short implants and 1.38 ± 0.69 mm at standard-length implants, and trabecular bone computed tomography values of implant insertion sites was 424.1 ± 290.1 at short implants and 410.9 ± 267.9 at standard-length implants. The MBL changes were -0.30 ± 0.71 mm at short implants and -0.19 ± 0.78 mm at standard-length implants at 3 years follow-up visit. No significant difference was found in the average of MBL changes between implant length.

Conclusions

Within the limits of this study, it can be concluded that 6 mm short implants in a posterior edentulous region showed excellent results compared with conventional implants.

New classification for bone type at dental implant sites: a dental computed tomography study

OBJECTIVE

This study proposed a new classification method of bone quantity and quality at the dental implant site using cone-beam computed tomography (CBCT) image analysis, classifying cortical and cancellous bones separately and using CBCT for quantitative analysis.

METHODS

Preoperative CBCT images were obtained from 128 implant patients (315 sites). First, measure the crestal cortical bone thickness (in mm) and the cancellous bone density [in grayscale values (GV) and bone mineral density (g/cm³)] at the implant sites. The new classification for bone quality at the implant site proposed in this study is a "nine-square division" bone classification system, where the cortical bone thickness is classified into A: > 1.1 mm, B:0.7-1.1 mm, and C: < 0.7 mm, and the cancellous bone density is classified into 1: > 600 GV (= 420 g/cm³), 2:300-600 GV (= 160 g/cm³-420 g/cm³), and 3: < 300 GV (= 160 g/cm³).

RESULTS

The results of the nine bone type proportions based on the new jawbone classification were as follows: A1 (8.57%,27/315), A2 (13.02%), A3 (4.13%), B1 (17.78%), B2 (20.63%), B3 (8.57%) C1 (4.44%), C2 (14.29%), and C3 (8.57%).

CONCLUSIONS

The proposed classification can complement the parts overlooked in previous bone classification methods (bone types A3 and C1).

TRIAL REGISTRATION

The retrospective registration of this study was approved by the Institutional Review Board of China Medical University Hospital, No. CMUH 108-REC2-181.

Bone resorption after maxillary reconstruction with the vascularized free iliac flap

The aim of this study was to evaluate the resorption of the iliac bone after maxillary reconstruction with a vascularized free iliac flap. Twenty-seven patients with maxillary defects who underwent maxillary reconstruction with the vascularized free iliac flap between January 2017 and January 2021 were included. Computed tomography (CT) images taken at 1 week, approximately 6 months, and 1 year after the surgery were used for evaluation. The total iliac bone thickness and height, cortical bone thickness, and cancellous bone density were measured in the CT images. Compared with 1 week after the surgery, the total thickness and height of the iliac bone were reduced significantly 1 year after the surgery, and the cortical bone thickness and cancellous bone density were reduced significantly at 6 months and 1 year after the surgery. Compared with 6 months after the surgery, cancellous bone density was reduced significantly 1 year after the surgery. In conclusion, during the first year after maxillary reconstruction with a vascularized free iliac flap, there was significant resorption of iliac bone, including the total iliac bone thickness and height, the cortical bone thickness, and the cancellous bone density.

The Effect of General Bone Mineral Density on the Quantity and Quality of the Edentulous Mandible: A Cross-Sectional Clinical Study

BACKGROUND

Osteoporosis is a disease which is characterized by a decrease in general bone mineral density (BMD), resulting in decreased bone strength and an increased risk of bone fractures. The effect of reduced BMD on the jawbones is still not fully understood. The purpose of the study was to evaluate the impact of BMD on the quality and quantity of the edentulous mandible.

METHODS

The present study included 127 edentulous postmenopausal women who underwent cone beam computed tomography (CBCT) examinations. BMD measurements of the lumbar spine and femoral necks were performed by dual-energy X-ray absorptiometry. In the cross-sectional CBCT images, three different areas of the mandible (lateral incisor, first premolar, and first molar) were selected. The complete mandibular, trabecular, and cortical bone volumes were measured. All measurements were performed on the total mandibular area, and the basal and alveolar parts of the mandible.

RESULTS

The volume of the cortical bone was reduced for females with reduced BMD in the lateral incisor and first premolar regions, both in the total mandibular area and in the basal part of the mandible. The trabecular bone volume statistically significantly increased when the BMD decreased in the complete mandibular area and the basal part of the mandible (linear regression). The total bone volume significantly decreased with a decrease in BMD in the basal part of the mandible.

CONCLUSIONS

Reduced BMD has a negative effect on the quantity and quality of bone in the basal part of the edentulous mandible.

Cone Beam CT Assessment of Bone Width of Upper and Lower Jaws for Dental Implant Placement: An Iraqi Study

Background

Implantology focuses on the measurement of bone thickness in both the lower and upper jaws. This study aimed to measure and compare alveolar bone thickness of the upper and lower jaws at single edentate sites and cortical bone thickness of their mesial and distal dentate sites.

Methods

Thickness of alveolar bone thickness was measured in 80 upper and 80 lower implant edentate sites and that of buccal and lingual cortical plates of their mesial and distal dentate sites using Cone beam CT. The bone thickness of the edentulous sites was recorded at 3 points (crestal bone, five mm from the crest, and ten mm from the crest), while the bone thickness of the dentate sites was determined at four points (crestal bone, midroot bone, mid of the alveolar bone housing, and apical portion).

Results

An increased amount of bone was measured from the crest to the apical portion of the dentate sites on the buccal and lingual sides of both jaws with a highly significant difference detected among all the tested points (P <  0.0001). No statistical difference was detected between the means of buccal bone width at the first 3 points, except at point 4 (the apical portion), where the mean of the lower jaw (3.35 ± 0.54) was significantly larger than that of the upper jaw (3.17 ± 0.55) (P = 0.04). Bone width measured in the edentulous sites showed a gradual increase from the crest to the apical portions in both jaws.

Conclusion

Bone thickness at the coronal levels is low and susceptible to resorption compared to the apical portions regardless of the dentate state.

Evaluation of Cortical Bone Thickness of Posterior Implant Sites Using CBCT in Iraqi Population

Background. Cortical bone thickness (CBT) is a critical factor for implant success and for determining the long-term dental implant treatment outcome. Objectives. The objective of this investigation was to examine posterior cortical bone thickness buccally and lingually in dentate and edentulous implant sites according to gender. Materials and Methods. CBT of 160 patients requiring a single posterior tooth implant was investigated by CBCT. The study included 80 males and 80 females. CBT was measured for implant edentulous sites at 3 levels including crestal bone (level 1), five mm from the crest (level 2), and ten mm from the crest (level 3). CBT was also measured for dentate sites at 3 levels including crestal bone (level 1), midroot bone (level 2), and apical portion (level 3). The differences of bone thickness between the levels of dentate sites were statistically analyzed using a Kruskal–Wallis one-way analysis of variance. Mann–Whitney test was used to determine the specific differences between group members. For the edentulous site, a one-way ANOVA was used. Results. CBT increased gradually from the crestal level to the apical level in all groups (buccal and lingual side, male and female). However, CBT at lingual side was statistically higher than that at buccal side in all groups. The mean value of CBT was significantly higher in males than females for both edentulous and dentate site. The dentate site shows a higher CBT in the apical level than the edentulous group in both male and female/buccal and lingual groups. Conclusion. CBT at the coronal levels is low and susceptible for resorption compared to the apical portion, especially for the female group. Moreover, CBT is thicker in males than females. It is essential to measure the CBT before making a treatment plan with dental implant prosthesis.

Insertion Speed Affects the Initial Stability of Dental Implants

Purpose

This study investigated the effects of insertion speed of dental implants on their stability.

Methods

Dental implants were inserted at speeds of 4, 10, 20, and 30 rpm, respectively, into artificial bones of two different bone qualities; namely, good bone (GB) and poor bone (PB). Therefore, the four insertion speeds and two bone qualities totaled eight groups, with five specimens per group. During the insertion process, the maximum insertion torque value (ITV) was measured, along with two stability parameters: periotest value (PTV) and initial stability quotient (ISQ).

Results

Dental implants in the GB group exhibited better stability than those in the PB group (p < 0.001). Significant differences in ITVs were observed among the four insertion speeds in both the GB and PB groups (p = 0.004 and p = 0.034, respectively). In general, the higher the insertion speed, the lower the ITV; in particular, the ITVs for implants inserted at 4 rpm were higher than those measured at 20 and 30 rpm (p = 0.008). However, regardless of the bone quality, the PTVs did not differ significantly among the four insertion speeds (p = 0.066). In both the GB and PB groups, the ISQs differed significantly differences among the four insertion speeds (p = 0.016 and p = 0.004, respectively).

Conclusion

The stability parameters measured for dental implants in the GB group were all higher than those measured in the PB group. In general, a higher insertion speed resulted in a lower ITV value. The PTV did not differ significantly, while the ISQ differed significantly among the four insertion speeds.

Accuracy of Mini-Implant Placement Using a Computer-Aided Designed Surgical Guide, with Information of Intraoral Scan and the Use of a Cone-Beam CT

Background: The purpose of the study was to investigate the accuracy of mini-implant placement with the use of a computer designed surgical guide derived by intraoral scanning alongside Cone-Beam Computed Tomography (CBCT) or the use of a 2D radiograph. Methods: Thirty-five mini-implants (Aarhus^® System: n = 20, Ø: 1.5 mm and AbsoAnchor^®: n = 15, Ø: 1.3–1.4 mm) were placed in the maxilla and mandible of 15 orthodontic patients for anchorage purposes in cases where a CBCT was needed due to impacted teeth or for safety reasons. All were placed with the help of a computer designed surgical guide. One implant became loose and was excluded from the study. For 18 mini-implants (study group), CBCT and intraoral scanning were used for guide design, while for 16 (control group) only intraoral scanning and panoramic imaging information were used. Mini-implant position was recorded by angular and linear measurements on digital models created by combining Digital Imaging and Communications in Medicine (DICOM) and stereolithography (.stl) files. Accuracy in positioning was determined by comparing corresponding measurements for virtual and real positioned mini-implants on digital models before and after operation. The results were statistically analyzed with t-tests and the Mann-Whitney test. Results: No significant statistical differences were found for pre- and post-operational angular measurements in the study group, while significant statistical differences occurred on the same measurements for the control group (coronal angle 13.6° pre-op and 22.7° post-op, p-value = 0.002, axial angle 13.4° pre-op and 15.9° post-op, p-value = 0.034). Linear measurements pre- and post-operational for either group presented no significant statistical differences. Conclusions: A 3D designed and manufactured surgical guide with information concerning CBCT and intraoral scanning ensures accuracy on mini-implant placement while design of the guide without the use of a CBCT is less accurate, especially on inclination of the implant.

Effect of implant crestal position on primary stability before and after loading: an in vitro study

Abstract Introduction Primary stability is one of the goals of modern implant dentistry and if achieved, reduces treatment time for prosthetic rehabilitation and the number of interventions made in patients mouth. Several companies state as protocol for connical conection implants, a subcrestally positioning. Objective This in vitro study aimed to evaluate the effect of placing a conical connection implant equicrestally and subcrestally on static and loading condition in two types of bone density. Material and method A total of 200 bone cylinders were extracted from femur of pigs, standardized by means of x-rays and computerized microtomography scan (microCT) and separated in low and high density specimens. The implants were placed on the center of the bone cylinders and were evaluated before and after loading by means of microCT and histomorphometry. Result The results showed that placing the evaluated implant subcrestally provided better primary stability and performance on static and loading situations on low and high density bone. Conclusion Placing implant subcrestally improve primary stability outcomes under loading and static situations.

[Possibilities and prospects for experimental and clinical instrumentation techniques for determining the primary stability of dental implants in comparative analysis]

The high primary stability of dental implants provides a favorable prognosis for orthopedic treatment with implant-supported structures. The importance of assessing the stability and the bone tissue surrounding the implant as a whole is due to the fact that the process of osseointegration is a structural and functional connection between the bone and the loaded surface of the implant. Determination of the dynamics of the stability of dental implants allows timely monitoring of unpredictable changes at the stages of osseointegration and remodeling of bone tissue around the implant. Currently, in addition to clinical and radiation diagnostic methods, there are generally recognized by clinicians frequency resonance analysis and periotestometry. However, there are some scientific discrepancies indicating the lack of objectivity of these methods and the impossibility of their full-fledged application without the support of radiation and clinical diagnostic methods. In addition to these methods, there are many experimental and less common methods in clinical practice for assessing the primary stability of implants, but with reasonable objectivity. Thus, the reasons are given that for a full assessment of the relationship between the efforts exerted on implants and their movements in the space of bone tissue, devices are needed that reflect the stability and density of the contact of the implant with bone tissue in physical quantities. In particular, methods based on lasers, sound, quantitative ultrasound, and others have found experimental practical application. The ultrasound method of assessing the primary stability of the implant is estimated as the most promising, since it allows you to demonstrate the results of studies in certain physical quantities, as well as to compare these results with histomorphological indicators of osseointegration of dental implants.

Stability of Dental Implants and Thickness of Cortical Bone: Clinical Research and Future Perspectives. A Systematic Review

Dental surgery implantation has become increasingly important among procedures that aim to rehabilitate edentulous patients to restore esthetics and the mastication ability. The optimal stability of dental implants is correlated primarily to the quality and quantity of bone. This systematic literature review describes clinical research focusing on the correlation between cortical bone thickness and primary/secondary stability of dental fixtures. To predict successful outcome of prosthetic treatment, quantification of bone density at the osteotomy site is, in general, taken into account, with little attention being paid to assessment of the thickness of cortical bone. Nevertheless, local variations in bone structure (including cortical thickness) could explain differences in clinical practice with regard to implantation success, marginal bone resorption or anchorage loss. Current knowledge is preliminarily detailed, while tentatively identifying which inconclusive or unexplored aspects merit further investigation.

Prosthetic aftercare, mastication, and quality of life in mandibular overdenture wearers with narrow implants: A 3-year cohort study

OBJECTIVES

This cohort study investigated clinical, functional, and quality of life outcomes, along with prosthetic maintenance events in mandibular overdenture (MO) wearers for 3 years.

METHODS

Thirty MO wearers with narrow diameter implants (NDIs) and locking taper stud abutments (Facility-Equator system) were annually monitored by registering the visible plaque index (VPI), peri‑implant inflammation (PI), calculus presence (CP), probing depth (PD), bleeding on probing (BOP), secondary implant stability (ISQ), marginal bone loss (MBL), masticatory performance and dental impact in daily life (DIDL) questionnaire domains. Multilevel mixed-effects linear regression was performed to analyse changes over time. Chi-square tests were performed to analyse the relationship between the appearance of prosthetic complications and maintenance occurrences. The survival rate of patients with NDIs was calculated using the Kaplan-Meier test.

RESULTS

Twenty-six individuals attended all follow-ups, the survival rate of 83.3% in the first year was maintained, and no one implant was lost over the 3-year period. There were significant differences for PD between 1 and 3 years (p ≤ 0.01) and between 2 and 3 years for PI (p ≤ 0.01), GI (p ≤ 0.01), ISQ (p = 0.02), and MBL (p ≤ 0.01). All masticatory performance outcomes showed significant differences (p ≤.01). Prosthetic maintenance events decreased significantly over time. Appearance, general performance, and eating and chewing domains presented high effect sizes.

CONCLUSION

Continued changes were observed in the clinical parameters of MO users over the 3-year period. In addition, most functional parameters, except for particle homogenization, improved significantly over time. The positive impact on quality of life is likely related to the significant reduction in prosthetic maintenance events.

CLINICAL SIGNIFICANCE

Periodic returns to assess peri‑implant tissues and MO maintenance should be performed to ensure the success of rehabilitation to assure improvements in masticatory function and oral health-related quality of life.

Reliability and Correlation of Different Devices for the Evaluation of Primary Implant Stability: An In Vitro Study

Our aim was to analyze the correlation between the IT evaluated by a surgical motor and the primary implant stability (ISQ) measured by two RFA devices, Osstell and Penguin, in an in vitro model. This study examines the effect of bone type (soft or dense), implant length (13 mm or 8 mm), and implant design (CC: conical connection; IH: internal hexagon), on this correlation. Ninety-six implants were inserted using a surgical motor (IT) into two types of synthetic foam blocks. Initial measurements for both the peak IT and ISQ were recorded at the point when implant insertion was stopped by the surgical motor, and the final measurements were recorded when the implant was completely inserted into the synthetic blocks using only the RFA devices. Our null hypothesis was that there is a good correlation between the devices, independent of the implant length, design, or bone type. We found a positive, significant correlation between the IT, and the Osstell and Penguin devices. Implant length and bone type did not affect this correlation. The correlation between the devices in the CC design was maintained; however, in the IH design it was maintained only between the RFA devices. We concluded that there is a high positive correlation between the IT and ISQ from a mechanical perspective, which was not affected by bone type or implant length but was affected by the implant design.

An experimental study on the effects of the cortical thickness and bone density on initial mechanical anchorage of different Straumann® implant designs

Background

The aim of the current study was to comparatively assess the primary stability of different Straumann® implant designs (BLX, Straumann Tapered Effect, Bone Level Tapered, and Standard Plus) via resonance frequency analysis by using an implant insertion model in freshly slaughtered bovine ribs with and without cortical bone. Tapered Effect (4.1 × 10 mm), Bone Level Tapered (4.1 × 10 mm), Standard Plus (4.1 × 10 mm), and BLX (4.0 × 10 mm) implants were inserted into the distal epiphysis on the longitudinal axis of the freshly slaughtered bovine ribs. As a control, implants with the same sizes were inserted into the proximal diaphysis. The stability of the implants was examined with resonance frequency analysis.

Results

BLX and Tapered Effect implants showed higher implant stability quotient values in both study and control groups. All implant systems showed a significant decrease of mechanical anchorage in the study group. BLX and Bone Level Tapered designs had a significantly lower loss of mechanical anchorage in the lack of cortical bone.

Conclusion

Both Tapered Effect and BLX designs could ensure sufficient initial stability; however, BLX implants could be an appropriate option in the lack of cortical bone and poor bone quality at the implant recipient site.

Clinical relevance

BLX is a novel implant system, which could be especially beneficial in the presence of spongious bone type at posterior maxillae.

Can the Bone Density Estimated by CBCT Predict the Primary Stability of Dental Implants? A New Measurement Protocol

BACKGROUND

The use of dental implants to restore edentulous parts of the jaws is a common and well-documented treatment method. Effective dental implant treatment is known to be affected by both the quality and the quantity of bone required for implant placement, bone quality is a critical factor to consider when predicting stability of implants. Thus, stability of the initial implant and the possibility of early loading could be predicated using cone-beam computed tomography (CBCT) scans and primary stability parameters before implant placement.

OBJECTIVES

The aim of this study was to objectively assess bone density obtained by CBCT and the correlations with primary stability of dental implants using implant stability meter IST device.

METHODS

A total of 40 implants were placed in 16 patients (9 males and 7 females with a range of 22 to 61 years (mean age 40.44 ± 12.3 years). The bone densities of implant recipient sites were preoperatively recorded using CBCT. The maximum insertion torque value of each implant was measured by engine during implant placement and compared to the primary stability for every implant using implant stability meter device (IST).

RESULTS

A statistically significant correlation was found between bone density value from CBCT with the primary implant stability and insertion torque.

CONCLUSION

Although the small samples size, the study shown bone density assessment using CBCT is an efficient method and significantly correlated with primary stability using implant stability meter device IST and insertion torque.

Influence of Inter-Radicular Septal Bone Quantity in Primary Stability of Immediate Molar Implants with Different Length and Diameter Placed in Mandibular Region. A Cone-Beam Computed Tomography-Based Simulated Implant Study

AIM

The purpose of this in vitro study was to investigate the influence of length and width of implant on primary stability in immediate implants in mandibular first molar.

MATERIALS AND METHODS

The study was carried out on 40 cone-beam computed tomography scans selected with defined inclusion and exclusion criteria. According to the diameter and length of implants, they were divided into nine groups (G1 to G9). The virtual implants of different diameters and length were placed in mandibular first molar and measurements were done for peri-implant horizontal and vertical gap defect, peri-implant interradicular bone support and apical bone support for all the groups.

RESULTS

The study groups Diameter, (D-7 mm) showed least horizontal gap defect (Buccal-1.30 ± 0.56 mm, lingual-1.30 ± 0.56 mm, mesial-1.20 ± 0.51 mm, and distal-1.05 ± 0.59 mm) as compared to regular implant diameter (D-4.7) groups (Buccal-2.35 ± 0.483 mm, lingual-2.10 mm ± 0.44 mm, mesial-2.30 ± 0.64 mm, and distal-2.25 ± 0.43 mm). The unsupported Vertical implant gap defect at the coronal part of the socket was 2.80 mm ± 0.83 mm for all groups in both horizontal and vertical direction. The vertical peri-implant interradicular bone support showed increased bone support with increase in implant length (L). The buccal and lingual inter-radicular bone-support was least for Length (L-8.5 mm), moderate for L-11.5 mm, and highest for L-13.5 mm groups, respectively. The mesial inter-radicular bone support was least for G4G7, moderate for G1G2G5G8, and maximum for G3G6G9 groups. Similarly, the distal inter-radicular bone support was least for G4G7, moderate for G1G5G8, and maximum for G2G3G6G9 groups, respectively. There was no apical bone support in L-8.5 mm group as the tip of implant was 3.5-4 mm within the socket tip. Whereas, L-11.5 mm had decent (0.9-1 mm) and L-13.5 mm had Good (1.35-1.95 mm) apical bone support as the implant tip was beyond the socket tip.

CONCLUSION

All the groups showed good interradicular bone support on buccal and lingual surfaces. Regular width implants with longer length showed satisfactory interradicular bone support on mesial and distal surfaces. Longer implants showed good apical bone support in all the four surfaces and hence good apical primary stability expected.

Effect of macrogeometry and bone type on insertion torque, primary stability, surface topography damage and titanium release of dental implants during surgical insertion into artificial bone

This study investigated the influence of implant macrogeometry and bone type on insertion torque (IT), primary stability (ISQ), surface topography damage, and the amount of titanium (Ti) released during insertion. Forty implants with different macrogeometries (Facility - Cylindrical with spiral-shaped threads; Alvim - Tapered with buttress-shaped threads) were inserted into artificial bone types I-II and III-IV. Surface morphology was evaluated by Scanning Electron Microscope (SEM) and roughness parameters with Laser Scanning Confocal Microscopy (LSCM) before and after insertion (AI). Implant macrogeometry was characterized by LSCM. The chemical composition of bone beds was determined by SEM associated with Energy Dispersive X-Ray Spectroscopy. The amount of Ti released was analyzed with Energy Dispersive X-Ray Fluorescence. Alvim had greater IT and ISQ than Facility. Bone types I-II require higher IT of implants. Alvim also had greater internal threads angle, higher initial roughness, and significant reduction of roughness AI, compared to Facility. The functional surface height reduced AI, especially in flank and valley of threads. Height of surface roughness of Alvim and Facility implants was similar AI. Implants surface morphology changes and metallic particles on bone beds were observed after implant insertion, mainly into bone types III-IV. Implants inserted into bone types I-II showed less surface damage. Alvim implants released more Ti (37.52 ± 25.03 ppm) than Facility (11.66 ± 28.55 ppm) on bone types III-IV. The implant macrogeometry and bone types affect IT, ISQ, surface damage, and Ti amount released during insertion. Alvim implants were more wear susceptible, releasing higher Ti concentration during insertion into bone types III-IV.

Can Male Patient's Age Affect the Cortical Bone Thickness of Jawbone for Dental Implant Placement? A Cohort Study

Dental implants are among the most common treatments for missing teeth. The thickness of the crestal cortical bone at the potential dental implant site is a critical factor affecting the success rate of dental implant surgery. However, previous studies have predominantly focused on female patients, who are at a high risk of osteoporosis, for the discussion of bone quality and quantity at the dental implant site. This study aimed to investigate the effect of male patients’ age on the crestal cortical bone of the jaw at the dental implant site by using dental cone-beam computed tomography (CBCT). This study performed dental CBCT on 84 male patients of various ages to obtain tomograms of 288 dental implant sites at the jawbone (41 sites in the anterior maxilla, 95 in the posterior maxilla, 59 in the anterior mandible, and 93 in the posterior mandible) for measuring the cortical bone thickness. A one-way analysis of variance and Scheffe’s test were performed on the measurement results to compare the cortical bone thickness at implant sites in the four jaw areas. The correlation between male patient age and cortical bone thickness at the dental implant site was determined. The four jaw areas in order of the cortical bone thickness were as follows: posterior mandible (1.07 ± 0.44 mm), anterior mandible (0.99 ± 0.30 mm), anterior maxilla (0.82 ± 0.32 mm), and posterior maxilla (0.71 ± 0.27 mm). Apart from dental implant sites in the anterior and posterior mandibles, no significant correlation was observed between male patients’ age and the cortical bone thickness at the dental implant site.

Effect of mandibular residual ridge regularization on peri-implant wound healing when narrow diameter implants are used as overdenture retainers

STATEMENT OF PROBLEM

Alveolar ridge regularization involves the smoothing and minimal reduction of rough alveolar bone ridge to achieve adequate bone thickness around the implant. The effect of this procedure on peri-implant health is unclear.

PURPOSE

The purpose of this clinical study was to evaluate whether bone regularization affects the clinical and biological parameters of peri-implant health when narrow diameter implants are placed as mandibular implant overdenture retainers during initial healing and after occlusal loading.

MATERIAL AND METHODS

The need for mandibular ridge regularization in the anterior mandibular region was analyzed before the placement of 2 implants (2.9×10 mm, Facility; Neodent) in 21 participants provided with mandibular overdentures. Primary stability was measured by the insertion torque and implant stability quotient (ISQ). Clinical and biological evaluations measuring the plaque index, presence of calculus, probing depth, bleeding on probing index, gingival index, secondary stability (ISQ), and interleukine-1β (IL-1β) and tumor necrosis factor-α (TNF-α) concentrations in peri-implant crevicular fluid were measured during osseointegration on days 7, 15, 30, 60, and 90 and after loading on day 180 after implant placement. Multilevel mixed-effects linear regression analysis and the Kaplan-Meier test were used to analyze the data (α=.05).

RESULTS

The ISQ values showed significant differences on days 7 (P<.001) and 15 (P=.002) with higher values and on day 180 (P=.008) with a lower value compared with the baseline value in the ridge regularization group. Additionally, a significant decrease in probing depth was observed on days 60 (P=.008) and 180 (P=.027) compared with that on day 15 after implant placement. In the nonridge regularization group, significant decreases in probing depth were observed on days 30 and 180. Moreover, TNF-α levels in this group were significantly lower on days 30 (P=.001), 60, 90, and 180 (P<.001) when compared with the value on day 7 (P<.001). The ridge regularization group presented with significant differences in TNF-α and IL-1β levels on days 60 (P=.004) and 30 (P=.007), respectively, when compared with the values on day 7. The ISQ and probing depth in the ridge regularization group were associated with changes in TNF-α and IL-1β levels; furthermore, bone type, duration of edentulism, and mandibular bone atrophy were correlated with the clinical outcomes and TNF-α release. The implant survival rate was 67% in the nonridge regularization group and 100% in the ridge regularization group.

CONCLUSIONS

Mandibular ridge regularization appeared to be beneficial for peri-implant healing during the early stages and after 3 months of occlusal loading in patients with an atrophic ridge, prolonged time since edentulism, and poor bone quality.

Evaluation of the Influence of Bone Resorption on Dental Implant Systems Using Taguchi Method and Finite Element Analysis

Dental implants are currently the mainstay of dental restoration procedures. They are used to reestablish normal chewing functions for patients. Several studies have reported their high success rate, but post-op bone resorption at the implant site increases the risk of implant fracture, which is especially significant in the posterior mandibular tooth (PMT) area. This study focused on bone resorption at the PMT area to assess and understand the mechanism of implant failure. This study used three implant systems on the posterior mandibular area. Computer tomography (CT) scans and reverse engineering were used to construct mandible and implant systems. The Taguchi method and finite element analysis (FEA) were used to explore the role of biting force on the components of various implant systems in the development of bone resorption. The results of this study found that when the implant site with bone resorption takes a biting force, the stress on the implant is inversely proportional to implant diameter and proportional to its length. For the stress loading, cortical bone thickness does not play a significant role. Instead, the most significant factor is implant diameter, followed by implant length. For better operation outcomes, it is recommended to use implants of larger diameter and less length. Also, it is recommended to avoid the use of implants less than 4.5 mm in diameter, regardless of the implant system, in order to prevent early implant damage or fracture due to bone resorption.

Design optimization of implant geometrical characteristics enhancing primary stability using FEA of stress distribution around dental prosthesis

The main objective of this study was to investigate the influence of implant geometrical characteristics: diameter, length and thread's pitch, on stress distribution around dental prosthesis. A set of numerical simulations using FEM were conducted and responses surfaces were generated. With the aim of optimizing the equivalent stresses responses; desirability function approach was adopted to solve this multi-objective problem. Results showed that implant diameter had most significant influence on generated stresses and high concentration of stresses were identified in the lower part of the implant. This study is helpful in choosing the optimal dental implant for clinical application.

Bone and Cartilage Interfaces With Orthopedic Implants: A Literature Review

The interface between a surgical implant and tissue consists of a complex and dynamic environment characterized by mechanical and biological interactions between the implant and surrounding tissue. The implantation process leads to injury which needs to heal over time and the rapidity of this process as well as the property of restored tissue impact directly the strength of the interface. Bleeding is the first and most relevant step of the healing process because blood provides growth factors and cellular material necessary for tissue repair. Integration of the implants placed in poorly vascularized tissue such as articular cartilage is, therefore, more challenging than compared with the implants placed in well-vascularized tissues such as bone. Bleeding is followed by the establishment of a provisional matrix that is gradually transformed into the native tissue. The ultimate goal of implantation is to obtain a complete integration between the implant and tissue resulting in long-term stability. The stability of the implant has been defined as primary (mechanical) and secondary (biological integration) stability. Successful integration of an implant within the tissue depends on both stabilities and is vital for short- and long-term surgical outcomes. Advances in research aim to improve implant integration resulting in enhanced implant and tissue interface. Numerous methods have been employed to improve the process of modifying both stability types. This review provides a comprehensive discussion of current knowledge regarding implant-tissue interfaces within bone and cartilage as well as novel approaches to strengthen the implant-tissue interface. Furthermore, it gives an insight into the current state-of-art biomechanical testing of the stability of the implants. Current knowledge reveals that the design of the implants closely mimicking the native structure is more likely to become well integrated. The literature provides however several other techniques such as coating with a bioactive compound that will stimulate the integration and successful outcome for the patient.

Drilling Capability of Orthodontic Miniscrews: In Vitro Study

The aims of this study were to assess the values and mechanical properties of insertion torque (IT) of steel miniscrews inserted in artificial bone blocks (Sawbones, Pacific Research Laboratories, Vashon, WA, USA) with different bone densities and to detect any scratches on the surface of the miniscrews after insertion. Forty self-drilling miniscrews (Leone S.p.A. ø 1.75 mm, L 8 mm) have been inserted into bone blocks that mimic different stability conditions (density: 20 PCF-pounds per cubic foot, 40 PCF, and 30 + 50 PCF with 2 mm and 4 mm of cortical bone). Before insertion and after removal, all miniscrews were inspected with a stereomicroscope 5x and a SEM to detect potential microscopic cracks. Using an electronic surgical motor (W&H Dentalwerk Bürmoos GmbH, Werner Bader Str. 1, 5111 Bürmoos, Austria), the maximum insertion torque value was registered. Stereomicroscope and SEM examination did not indicate any morphological and surface structural changes to the miniscrews, irrespective of the bone density they were inserted into. The findings showed that IT increased significantly with increasing bone density. In each artificial bone block, morphostructural analysis demonstrated the adequate mechanical properties of the self-drilling miniscrews. IT measurements indicated torque values between 6 and 10 Ncm for blocks with a density of 30 + 50 PCF, whereas the suggested values are between 5 and 10 Ncm.

Effects of Intrabony Length and Cortical Bone Density on the Primary Stability of Orthodontic Miniscrews

Miniscrews have gained recent popularity as temporary anchorage devices in orthodontic treatments, where failure due to sinus perforations or damage to the neighboring roots have increased. Issues regarding miniscrews in insufficient interradicular space must also be resolved. This study aimed to evaluate the primary stability of miniscrews shorter than 6 mm and their feasibility in artificial bone with densities of 30, 40, and 50 pounds per cubic foot (pcf). The primary stability was evaluated by adjusting the intrabony miniscrew length, based on several physical properties: maximum insertion torque (MIT), maximum removal torque (MRT), removal angular momentum (RAM), horizontal resistance, and micromotion. The MIT and micromotion results demonstrated that the intrabony length of a miniscrew significantly affected its stability in low-density cortical bone, unlike cases with a higher cortical bone density (p < 0.05). The horizontal resistance, MRT, and RAM were affected by the intrabony length, regardless of the bone density (p < 0.05). Thus, the primary stability of miniscrews was affected by both the cortical bone density and intrabony length. The effect of the intrabony length was more significant in low-density cortical bone, where the implantation depth increased as more energy was required to remove the miniscrew. This facilitated higher resistance and a lower risk of falling out.

Does implant surface hydrophilicity influence the maintenance of surface integrity after insertion into low-density artificial bone?

OBJECTIVE

To evaluate the influence of hydrophilicity on the surface integrity of implants after insertion in low-density artificial bone and to determine the distribution of titanium (Ti) particles along the bone bed.

METHODS

Forty-eight dental implants with different designs (Titamax Ex, Facility, Alvim, and Drive) and surface treatments (Neoporos® and Aqua™) were inserted into artificial bone blocks with density compatible with bone type III-IV. Hydrophobic Neoporos® surfaces were obtained by sandblasting and acid etching while hydrophilic Aqua™ surfaces were obtained by sandblasting, acid etching, and storage in an isotonic 0.9% NaCl solution. The surface integrity was evaluated by Scanning Electron Microscope (SEM) and the surface roughness parameters (Sa, Sp, Ssk, Sdr, Spk, Sk, and Svk) and surface area were measured with Laser Scanning Confocal Microscopy before and after installation. Bone beds were inspected with Digital Microscopy and micro X-Ray Fluorescence (μ-XRF) to analyze the metallic element distribution along the bone bed.

RESULTS

Acqua™ implants had higher initial Sa and a pronounced reduction of Sa and Sp during insertion, compared to NeoPoros® implants. After insertion, Sa and Sp of Acqua™ and NeoPoros® implants equalized, differing only between designs of Acqua™ implants. Surface damage was observed after insertion, mainly in the apical region. Facility implants that are made of TiG5 released fewer debris particles, while the highest Ti intensity was detected in the cervical region of the Titamax Ex Acqua™ and Drive Acqua™ implants.

SIGNIFICANCE

Physicochemical modifications to achieve surface hydrophilicity created a rougher surface that was more susceptible to surface alterations, resulting in more Ti particle release into the bone bed during surgical insertion. The higher Ti intensities detected in the cervical region of bone beds may be related to peri-implantitis and marginal bone resorption.

Factors Influencing Primary and Secondary Implant Stability—A Retrospective Cohort Study with 582 Implants in 272 Patients

The success rate of dental implants depends on primary and secondary stability. We investigate predictive factors for future risk stratification models. We retrospectively analyze 272 patients with a total of 582 implants. Implant stability is measured with resonance frequency analysis and evaluated based on the implant stability quotient (ISQ). A linear regression model with regression coefficients (reg. coeff.) and its 95% confidence interval (95% CI) is applied to assess predictive factors for implant stability. Implant diameter (reg. coeff.: 3.28; 95% CI: 1.89–4.66, p < 0.001), implant length (reg. coeff.: 0.67, 95% CI: 0.26–1.08, p < 0.001), and implant localization (maxillary vs. mandibular, reg. coeff.: −7.45, 95% CI: −8.70–(−6.20), p < 0.001) are significant prognostic factors for primary implant stability. An increase in ISQ between insertion and exposure is significantly correlated with healing time (reg. coeff.: 0.11, 95% CI: 0.04–0.19). Patients with maxillary implants have lower ISQ at insertion but show a higher increase in ISQ after insertion than patients with mandibular implants. We observe positive associations between primary implant stability and implant diameter, implant length, and localization (mandibular vs. maxillary). An increase in implant stability between insertion and exposure is significantly correlated with healing time and is higher for maxillary implants. These predictive factors should be further evaluated in prospective cohort studies to develop future preoperative risk-stratification models.

Influence of bone condition on implant placement accuracy with computer-guided surgery

BACKGROUND

The impact of the jaw bone condition, such as bone quantity and quality in the implant placement site, affecting the accuracy of implant placement with computer-guided surgery (CGS) remains unclear. Therefore, this study aimed to evaluate the influence of bone condition, i.e., bone density, bone width, and cortical bone thickness at the crestal bone on the accuracy of implant placement with CGS.

METHODS

A total of 47 tissue-level implants from 25 patients placed in the posterior mandibular area were studied. Implant placement position was planned on the simulation software, Simplant® Pro 16, by superimposing preoperative computed tomography images with stereolithography data of diagnostic wax-up on the dental cast. Implant placement surgery was performed using the surgical guide plate to reflect the planned implant position. The post-surgical dental cast was scanned to determine the position of the placed implant. Linear and vertical deviations between planned and placed implants were calculated. Deviations at both platform and apical of the implant were measured in the bucco-lingual and mesio-distal directions. Intra- and inter-observer variabilities were calculated to ensure measurement reliability. Multiple linear regression analysis was employed to investigate the effect of the bone condition, such as density, width, and cortical bone thickness at the implant site area, on the accuracy of implant placement (α = 0.05).

RESULT

Intra- and inter-observer variabilities of these measurements showed excellent agreement (intra class correlation coefficient ± 0.90). Bone condition significantly influenced the accuracy of implant placement using CGS (p < 0.05). Both bone density and width were found to be significant predictors.

CONCLUSIONS

Low bone density and/or narrow bucco-lingual width near the alveolar bone crest in the implant placement site might be a risk factor influencing the accuracy of implant placement with CGS.

Relationship between Cortical Bone Thickness and Cancellous Bone Density at Dental Implant Sites in the Jawbone

Dental implant surgery is a common treatment for missing teeth. Its survival rate is considerably affected by host bone quality and quantity, which is often assessed prior to surgery through dental cone-beam computed tomography (CBCT). Dental CBCT was used in this study to evaluate dental implant sites for (1) differences in and (2) correlations between cancellous bone density and cortical bone thickness among four regions of the jawbone. In total, 315 dental implant sites (39 in the anterior mandible, 42 in the anterior maxilla, 107 in the posterior mandible, and 127 in the posterior maxilla) were identified in dental CBCT images from 128 patients. All CBCT images were loaded into Mimics 15.0 to measure cancellous bone density (unit: grayscale value (GV) and cortical bone thickness (unit: mm)). Differences among the four regions of the jawbone were evaluated using one-way analysis of variance and Scheffe's posttest. Pearson coefficients for correlations between cancellous bone density and cortical bone thickness were also calculated for the four jawbone regions. The results revealed that the mean cancellous bone density was highest in the anterior mandible (722 ± 227 GV), followed by the anterior maxilla (542 ± 208 GV), posterior mandible (535 ± 206 GV), and posterior maxilla (388 ± 206 GV). Cortical bone thickness was highest in the posterior mandible (1.15 ± 0.42 mm), followed by the anterior mandible (1.01 ± 0.32 mm), anterior maxilla (0.89 ± 0.26 mm), and posterior maxilla (0.72 ± 0.19 mm). In the whole jawbone, a weak correlation (r = 0.133, p = 0.041) was detected between cancellous bone density and cortical bone thickness. Furthermore, except for the anterior maxilla (r = 0.306, p = 0.048), no correlation between the two bone parameters was observed (all p > 0.05). Cancellous bone density and cortical bone thickness varies by implant site in the four regions of the jawbone. The cortical and cancellous bone of a jawbone dental implant site should be evaluated individually before surgery.

Association between Age of Menopause and Thickness of Crestal Cortical Bone at Dental Implant Site: A Cross-Sectional Observational Study

Satisfactory host bone quality and quantity promote greater primary stability and better osseointegration, leading to a high success rate in the use of dental implants. However, the increase in life expectancy as a result of medical advancements has led to an aging population, suggesting that osteoporosis may become a problem in clinical dental implant surgery. Notably, relative to the general population, bone insufficiency is more common in women with post-menopausal osteoporosis. The objective of this study was to compare the thickness of the crestal cortical bone at prospective dental implant sites between menopausal and non-menopausal women. Prospective dental implant sites in the jawbone were evaluated in two groups of women: a younger group (<50 years old), with 149 sites in 48 women, and an older group (>50 years old) with 191 sites, in 37 women. The thickness of the crestal cortical bone at the dental implant site was measured based on each patient’s dental cone-beam computed tomography images. For both groups, one-way analysis of variance and Tukey’s post-test were used to assess the correlation between cortical bone thickness and the presence of implants in the four jawbone regions. Student’s t-test was further used to compare differences between the older and younger groups. From the retrospective study results, for both groups, thickness of the crestal cortical bone was the highest in the posterior mandible, followed by anterior mandible, anterior maxilla, and posterior maxilla. Compared with the younger group, the older group had a lower mean thickness of the crestal cortical bone. Among the four regions, however, only in the posterior maxilla was the crestal cortical bone significantly thinner in the older group than in the younger group.

Influence of Bone Quality, Drilling Protocol, Implant Diameter/Length on Primary Stability: An In Vitro Comparative Study on Insertion Torque and Resonance Frequency Analysis

The aim of this study was to evaluate the influence of bone quality, drilling technique, implant diameter, and implant length on insertion torque (IT) and resonance frequency analysis (RFA) of a prototype-tapered implant with knife-edge threads. The investigators hypothesized that IT would be affected by variations in bone quality and drilling protocol, whereas RFA would be less influenced by such variables. The investigators implemented an in vitro experiment in which a prototype implant was inserted with different testing conditions into rigid polyurethane foam blocks. The independent variables were: bone quality, drilling protocol, implant diameter, and implant length. Group A implants were inserted with a conventional drilling protocol, whereas Group B implants were inserted with an undersized drilling protocol. Values of IT and RFA were measured at implant installation. IT and RFA values were significantly correlated (Pearson correlation coefficient: 0.54). A multivariable analysis showed a strong model. Higher IT values were associated with drilling protocol B vs A (mean difference: 71.7 Ncm), implant length (3.6 Ncm increase per mm in length), and substrate density (0.199 Ncm increase per mg/cm3 in density). Higher RFA values were associated with drilling protocol B vs A (mean difference: 3.9), implant length (1.0 increase per mm in length), and substrate density (0.032 increase per mg/cm3 in density). Implant diameter was not associated with RFA or IT. Within the limitations of an in vitro study, the results of this study suggest that the studied implant can achieve good level of primary stability in terms of IT and RFA. A strong correlation was found between values of IT and RFA. Both parameters are influenced by the drilling protocol, implant length, and substrate density. Further studies are required to investigate the clinical response in primary stability and marginal bone response.

Evaluation of the implant stability and the marginal bone level changes during the first three months of dental implant healing process: A prospective clinical study

Achievement of adequate implant stability is one of the determinants for long-term successful osseointegration. Resonance frequency analysis was developed to monitor implant stability and is now a well-recognized, non-invasive tool for determining the appropriate time for functional loading. However, there have been few studies with continuous evaluation and comparison of implant stability and marginal bone level changes between two different macro designs and clinical situations during the implant healing process. Thus, the purpose of this clinical trial is to evaluate the implant stability and marginal bone level changes of straight and conical implants during the implant healing process. In this prospective clinical trial, 25 participants were randomized to either straight or conical implants. A total of 32 titanium dental implants with a length of 9 mm or 11 mm were installed in the maxilla and the mandible according to the manufacturer's instructions. A resonance frequency analyzer was used to measure the implant stability quotient (ISQ) at the time of implant placement and after 2 weeks, 4 weeks, 6 weeks, 8 weeks, 10 weeks, and 12 weeks of healing. The changes in the peri-implant marginal bone level were evaluated from digital radiographic films taken at the time of implant placement and after 4 weeks, 8 weeks, and 12 weeks of healing. The preliminary results of this study revealed higher ISQ values and better healing tendency for conical implants in comparison with straight implants in the maxilla. Similar ISQ values and healing tendency were observed for straight and conical implants in the mandible. No significant differences in marginal bone loss were found between the straight and conical implants. However, in the mandible, slightly more marginal bone loss was found with the conical implants than straight implants after 12 weeks of healing. In conclusion, ISQ healing tendency and marginal bone loss are influenced by implant macro-design and jaw regions. Straight implants revealed similar ISQ healing tendency and marginal bone loss in both the mandible and maxilla. Conical implants were confirmed more beneficial for maintenance of implant stability and marginal bone level in the maxilla.

Morphological Evaluation of Bone by CT to Determine Primary Stability-Clinical Study

Background: Primary stability is an important prognostic factor for dental implant therapy. In the present study, we evaluate the relationship between implant stability evaluation findings by the use of an implant stability quotient (ISQ), an index for primary stability, and a morphological evaluation of bone by preoperative computed tomography (CT). Subjects and methods: We analyzed 98 patients who underwent implant placement surgery in this retrospective study. For all 247 implants, the correlations of the ISQ value with cortical bone thickness, cortical bone CT value, cancellous bone CT value, insertion torque value, implant diameter, and implant length were examined. Results: 1. Factors affecting ISQ values in all cases: It was revealed that there were significant associations between the cortical bone thickness and cancellous bone CT values with ISQ by multiple regression analysis. 2. It was revealed that there was a significant correlation between cortical bone thickness and cancellous bone CT values with ISQ by multiple regression analysis in the upper jaw. 3. It was indicated that there was a significant association between cortical bone thickness and implant diameter with ISQ by multiple regression analysis in the lower jaw. Conclusion: We concluded that analysis of the correlation of the ISQ value with cortical bone thickness and values obtained in preoperative CT imaging were useful preoperative evaluations for obtaining implant stability.

Relationship between Implant Length and Implant Stability of Single-Implant Restorations: A 12-Month Follow-Up Clinical Study

Background and Objectives: Implant stability in vivo is contingent on multiple factors, such as bone structure, instrument positioning and implant surface modifications, implant diameter, and implant length. Resonance-frequency analysis is considered a non-invasive, reliable, predictable, and objective method by which to evaluate implant stability, due to its correlation with bone-to-implant contact. The purpose of this study was to evaluate the effect of implant length on the primary and secondary stability of single-implant crown rehabilitations, as measured by resonance-frequency analysis at different times. Materials and Methods: Implants of 10 and 11.5 mm were placed, and the resonance frequency was measured at the time of surgery (T0), as well as at 3 (T1), 6 (T2), and 12 (T3) months post-surgery. Results: A total of 559 implants were placed in 195 patients. Significant differences were observed when comparing the implant stability quotient (ISQ) values at T1, with values for 10-mm implants being greater than those for 11.5-mm implants (p = 0.035). These differences were also observed when comparing ISQ values for buccal and lingual areas. At T0, T2, and T3, no significant differences in ISQ values were observed. The use of 10-mm implants in the anterior maxilla yielded significantly greater values at T0 (p = 0.018) and T1 (p = 0.031) when compared with 11.5-mm implants. Significant differences in measurements were observed only for buccal areas (p = 0.005; p = 0.018). When comparing the sample lengths and sex, women with 11.5-mm implants showed significantly lower results than those with 10-mm implants (p < 0.001). Conclusions: There is a direct relationship between implants of a smaller length and greater ISQ values, with this relationship being most evident in the maxilla and in women.

Influence of cortical bone and implant design in the primary stability of dental implants measured by two different devices of resonance frequency analysis: An in vitro study

Background

This study aimed to evaluate the effect of the implant design and the presence of cortical bone in the primary stability, as well as analyze the differences between the stability measurements obtained by two different resonance frequency analysis (RFA) devices.

Material and Methods

A total of 80 Klockner implants of two different models [40 Essential Cone implants (group A) and 40 Vega implants (group B)] were used. The implants were placed in two polyurethane blocks that simulated the mechanical properties of the maxillary bone. One block featured a layer of cortical bone that was absent from the other block. The primary stability of all implants was measured by insertion torque and RFA using two different devices: Penguin RFA and Osstell IDX.

Results

Primary stability was superior in the cortical bone in both torque and RFA. In the block containing cortical bone, group A implants obtained a greater insertion torque than did group B. The insertion torque was lesser in the bone lacking cortex. Regarding the ISQ of the implants, group A presented higher values in the block with cortical bone, but the values were lower in the block without cortical bone. There were no significant differences between the values obtained from the Osstell IDX and Penguin RFA.

Conclusions

The presence of cortical bone positively influences the primary stability of dental implants. The design of the implant also has a statistically significant influence on implant primary stability, although the impact depends on whether there is coronal cerclage or not. There were no statistically significant differences in the implant stability measurements obtained by two different devices.

Key words:Implant stability, resonance frequency analysis, torque, osstell, penguin, cortical.

Primary Stability of Three Different Osteotomy Techniques in Medullary Bone: An in Vitro Study

Background: The aim of this in vitro study was to analyse the primary stability of 20 implants placed with Twist drills (TD) versus 20 implants placed with Summers osteotomes (SO) and 20 implants placed with B&B bone compactors (BC) in medullary bone (quality type III and type IV). Methods: The implants were placed in 10 fresh pig ribs fixed on a bench vice in order to avoid micro-movements during surgical procedures and measure recording. Peak insertion torque (PIT) and Peak removal torque (PRT) were recorded with MGT-12 digital torque gauge and ISQ was recorded through OSSTELL ISQ™ device by an independent operator. Results: Comparing our data (Tukey test p = 0.05), it was evidenced a statistically significant difference in the PIT between TD and BC groups (p = 0.01). Analysing ISQ data, there was a statistically significant difference between the TD and BC groups (p = 0.0001) and between the SO and BC groups (p = 0.014). The analysis of PRT evidenced a statistically significant difference between the TD and BC groups (p = 0.038). Conclusions: This study evidenced that bone compactor preparation can positively influence primary implant stability (PS), however further in vivo studies and a larger sample are necessary to assess the usefulness in several clinical settings.