Hard Tissue Volume Research Articles

The effect of immediate implant placement on alveolar ridge preservation compared to spontaneous healing after tooth extraction: Soft tissue findings from a randomized controlled clinical trial.

To compare soft tissue dimensional changes and relative differences in soft and hard tissue volumes 4months after single-tooth extraction and three different treatment modalities: spontaneous healing (SH) and alveolar ridge preservation by means of a deproteinized bovine bone mineral and a collagen matrix, with (IMPL/DBBM/CM) or without (DBBM/CM) immediate implant placement. STL files from study casts obtained at baseline and after 4months were matched to calculate buccal soft tissue linear and volumetric changes. DICOM files from CBCTs were superimposed to STL files allowing the evaluation of soft tissue thickness at baseline and 4months. Mean horizontal reduction accounted for 1.46±0.20 (SH), 0.85±0.38 (DBBM-CM) and 0.84±0.30 IMPL/DBBM-CM, with no statistical differences. Soft tissue thickness had a significant mean increase of 0.95 for SH group, compared to a non-significant mean decrease for DBBM-CM (0.20) and IMPL/DBBM-CM groups (0.07). A preservation technique with DBBM-CM, with or without immediate implant placement, did not reduce the horizontal linear and volumetric changes at the buccal soft tissue profile significantly at 4months after tooth extraction when compared to spontaneous healing. This is due to a significant increase in soft tissue thickness in spontaneously healing sites.

Hard and soft tissue changes after guided bone regeneration using two different barrier membranes: an experimental in vivo investigation

To assess the contour and volumetric changes of hard and soft tissues after guided bone regeneration (GBR) using two types of barrier membranes together with a xenogeneic bone substitute in dehiscence-type defects around dental implants. In 8 Beagle dogs, after tooth extraction, two-wall chronified bone defects were developed. Then, implants were placed with a buccal dehiscence defect that was treated with GBR using randomly: (i) deproteinized bovine bone mineral (DBBM) covered by a synthetic polylactic membrane (test group), (ii) DBBM plus a porcine natural collagen membrane (positive control) and (iii) defect only covered by the synthetic membrane (negative control group). Outcomes were evaluated at 4 and 12weeks. Micro-CT was used to evaluate the hard tissue volumetric changes and STL files from digitized cast models were used to measure the soft tissues contour linear changes. Test and positive control groups were superior in terms of volume gain and contour changes when compared with the negative control. Soft tissue changes showed at 4weeks statistically significant superiority for test and positive control groups compared with negative control. After 12weeks, the results were superior for test and positive control groups but not statistically significant, although, with a lesser magnitude, the negative control group exhibited gains in both, soft and hard tissues. Both types of membranes (collagen and synthetic) attained similar outcomes, in terms of hard tissue volume gain and soft tissue contours when used in combination with DBBM CLINICAL RELEVANCE: Synthetic membranes were a valid alternative to the "gold standard" natural collagen membrane for treating dehiscence-type defects around dental implants when used with a xenogeneic bone substitute scaffold.

INFLUENCE OF DIFFERENT METHODS OF WHITENING ON THE STRUCTURE OF HARD TISSUES OF TEETH

Nowadays 74% of people believe that an imperfect smile has a negative impact on their careers, and 92% believe that it is one that contributes to success in their personal lives. The desire of patients to have an aesthetically perfect smile has always aroused great interest from dentists and has led to the active development of such a trend in aesthetic dentistry, such as teeth whitening. The color of the crowns of teeth and the inherent color characteristics play an important role in the perception of the appearance of the person, the formation of his image and self-esteem. Therefore, they affect the quality of life of a person due to his dental health. There are 5 main treatments for altered teeth: microabrasion, teeth whitening, direct restoration of composites, veneering, restoration of ceramic and metal-ceramic crowns. In recent years, conservative treatments, which include different types of whitening, have been favored to achieve maximum aesthetic results in the correction of altered teeth. For whitening, a considerable number of different remedies are offered that allow the tooth color to change relatively quickly. Nowadays, the world of dental practice is increasingly paying attention to the development of more cost-effective methods that meet the aesthetic needs of patients. The most common procedure for improving the color of the crowns of teeth today is whitening, which does not affect the reduction of the volume of hard tissues of the tooth. Teeth whitening is a restoration of the natural color of the teeth with the application of a chemical agent that oxidizes the organic pigments of the hard tissues of the tooth. Bleaching process is possible due to the ability of the active chemical components ( carbamide peroxide, hydrogen peroxide) to penetrate into enamel and dentin to all parts of the tooth. These substances break down into oxygen radicals, which destroy the colored pigments, the formation of which leads to discoloration of the teeth. The structure of the tooth does not change. Nowadays, home, professional and combined teeth whitening are widely used. The effect of bleaching is analyzed using a scanning electron microscope. Most studies did not report significant changes in the surface morphology of enamel after bleaching with low concentrations of urea peroxide and hydrogen peroxide. Similarly, studies evaluating the effects of higher concentrations of hydrogen peroxide (35%) and carbamidee peroxide (35%) have also reported no significant changes in the morphology of the enamel surface. In general, it is obvious that tooth sensitivity is a common clinical side effect after a teeth whitening procedure. However, the sensitivity is transient and disappears shortly after the bleaching procedure has been stopped.

ASSESSMENT OF SHEAR BOND STRENGTH OF RESTORATIVE MATERIALS IN VARIOUS DEPTH OF HARD DENTAL TISSUE PREPARATION IN FRONT TEETH

In modern dentistry, there are two different approaches to the restoration of anatomy and aesthetics of anterior teeth. The most common is the option of direct restoration with using composite resin materials. The second option is the restoration with using ceramic materials that is carried out through the cooperation of the dentists and the dental laboratory technicians, or, alternatively, with various CAD-CAM systems directly at the dental office. This experiment was carried out by using teeth (premolars, incisors) without significant loss of hard dental tissues. Teeth with abrasion (all except 1st degree) were excluded from the test group. Within the framework of the planned study, the selected extracted teeth were prepared (a certain volume of hard tissues was removed from the vestibular side (a subgroup of the teeth prepared within in the enamel layer, and a subgroup of teeth with the exposed dentine). A total of 40 teeth were prepared (20 teeth with the exposed dentine, 20 with the enamel preparation). The tests were carried out by using a universal testing machine AUTOGRAPH AGS-J. A sample with a tooth was placed at the top of the device then the second part of the sample containing the plate of the material (composite or ceramic), was covered with the second part of the device to be tested, and neatly, trying to avoid applying tension to the adhesive butt joints, and then fastened to the lower clamping device of the tension testing machine. We created the shear forces before the sample was destroyed, paying attention to the character of adhesion line oddments. The results of the experiment have demonstrated that the most optimal shear strength is found out in the complex of hard tooth tissues and ceramic materials IPS Empress Aesthetic and EX3, in the teeth prepared within the tooth enamel layer. When using composite resin, the values studied are lower by 11,4% and 18,1%, (application of adhesion systems of 5th and 7th generations, respectively). In the cases when dentin is exposed, the shear strength decreases by 19,5% when using ceramics modified by leucite glass, by 17,3% in the case of application of feldspar ceramics, and by 8,4% and 13,2% for composite resin restoration when using adhesive systems of 5th and 7Ith generations respectively.

Navigation-Assisted Orbital Trauma Reconstruction Using a Bioactive Osteoconductive/Bioresorbable u-HA/PLLA System.

Orbital fractures with orbital wall defects are common facial fractures encountered by oral-maxillofacial surgeons, because of the exposed position and thin bony walls of the midface. The primary goal of surgery is to restore the pre-injury anatomy and volume of hard tissue, and to free incarcerated or prolapsed orbital tissue from the fracture by bridging the bony defects with reconstructive implant material and restoring the maxillofacial-orbital skeleton. Numerous studies have reported orbital fracture repair with a wide variety of implant materials that offer various advantages and disadvantages. The ideal orbital implant material will allow conformation to individual patients' anatomical characteristics, remain stable over time, and are radiopaque, especially for the reconstruction of relatively large and/or complex bony walls. Based on these requirements, novel uncalcined and unsintered hydroxyapatite (u-HA) particles and poly-L-lactide (PLLA; u-HA/PLLA) composite sheets could be used as innovative, bioactive, and osteoconductive/bioresorbable implant materials for orbital reconstruction. In addition, intraoperative navigation is a powerful tool. Navigation- and computer-assisted surgeries have improved execution and predictability, allowing for greater precision, accuracy, and minimal invasiveness during orbital trauma reconstructive surgery of relatively complex and large orbital wall defects with ophthalmological malfunctions and deformities. This review presents an overview of navigation-assisted orbital trauma reconstruction using a bioactive, osteoconductive/bioresorbable u-HA/PLLA system.

Use of CBCT Guidance for Tooth Autotransplantation in Children

Tooth autotransplantation (TAT) offers a viable biological approach to tooth replacement in children and adolescents. The aim of this study was to evaluate the outcome of the cone-beam computed tomographic (CBCT)–guided TAT compared to the conventional TAT protocol and to assess the 3-dimensional (3D) patterns of healing after CBCT-guided TAT (secondary aim). This study included 100 autotransplanted teeth in 88 patients. Each experimental group consisted of 50 transplants in 44 patients (31 males and 19 females). The mean (SD) age at the time of surgery was 10.7 (1.1) y for the CBCT-guided group. This was 10.6 (1.3) y for the conventional group. The mean (SD) follow-up period was 4.5 (3.1) y (range, 1.1 to 10.4 y). Overall survival rate for the CBCT-guided TAT was 92% with a success rate of 86% compared to an 84% survival rate and a 78% success rate for the conventional group (P > 0.005). The following measurements were extracted from the 3D analysis: root hard tissue volume (RV), root length (RL), apical foramen area (AFA), and mean and maximum dentin wall thickness (DWT). Overall, the mean (SD) percentage of tissue change was as follows: RV gain by 65.8% (34.6%), RL gain by 37.3% (31.5%), AFA reduction by 91.1% (14.9%), mean DWT increase by 107.9% (67.7%), and maximum DWT increase by 26.5% (40.1%). Principal component analysis (PCA) identified the mean DWT, RV, and maximum DWT as the parameters best describing the tissue change after TAT. Cluster analysis applied to the variables chosen by the PCA classified the CBCT group into 4 distinct clusters (C1 = 37.2%, C2 = 17.1%, C3 = 28.6%, C4 = 17.1%), revealing different patterns of tissue healing after TAT. The CBCT-guided approach increased the predictability of the treatment. The 3D analysis provided insights into the patterns of healing. CBCT-guided TAT could be adopted as an alternative for the conventional approach. (Clinical trial center and ethical board University Hospitals, KU Leuven: S55287; ClinicalTrials.gov Identifier: NCT02464202)

A novel methodological approach using superimposed Micro-CT and STL images to analyze hard and soft tissue volume in immediate and delayed implants with different cervical designs.

To study the hard and soft tissue volume after placing immediate (IMI) or delayed implants (DLI) with a triangular coronal macro-design (Test/T) or a conventional cylindrical design (Control/C). T/C implants were inserted in healed ridges or in fresh extraction sockets of eight beagle dogs. Biopsies were processed for Micro-CT analysis and dental stone casts were optically scanned to obtain STL files revealing the soft tissue contours at 12weeks. Image analysis software was utilized to match common landmarks superimposing the two sets of data. Three distinct volumes were calculated; buccal bone volume (B-BV), soft tissue volume below the implant shoulder (EC-STV), and the soft tissue volume above the implant shoulder (SC-STV). Using linear measurements, the soft tissue height (STH), the mucosal thickness (MT-IS), and the distance from the implant shoulder to the bone crest (I-BC) were assessed in the digital images and in conventional histology to assess the concordance, reproducibility, and reliability. There were no significant differences between test and control implants regarding the buccal bone volume, although test implants had greater B-BV in all locations except for PM2. The soft tissue volume was similar at T/C implants. The surgical approach influenced the distribution of the total tissue volume. In the IMI, a low position of the bone crest was correlated with low values of B-BV, SC-STV, MT-IS, and STH. Linear measurements showed a high correlation between the histology and digital measurements and high inter and intra examiner agreement. The superimposition of Micro-CT/STL allowed the analysis of soft and hard tissue volumes. Reduction of the implant buccal aspect resulted in nonsignificant higher bone volume although similar soft tissue volume while the surgical approach influenced soft tissue response.

A Retrospective Case Series in Regenerative Endodontics: Trend Analysis Based on Clinical Evaluation and 2- and 3-dimensional Radiology

IntroductionA regenerative endodontic procedure (REP) is a biologically based treatment to functionally replace the pulp of infected immature permanent teeth. The purpose of this retrospective case series was to assess the outcome of REPs of infected immature permanent teeth in terms of periapical bone healing (PBH), root development (RD), and pulp vitality. MethodsFive patients (1 tooth/patient) who had undergone a REP based on the cell homing concept were recalled 3, 6, 12, 24, and 36 months postoperatively. At each recall session, clinical and periapical radiographic (PR) investigations were performed. Cone-beam computed tomographic (CBCT) imaging was taken before and 36 months after REPs. Qualitative and quantitative PR assessments were performed on the teeth that underwent REPs. Quantitative CBCT analyses were performed on the teeth that underwent REP and contralateral teeth. ResultsAt each recall session, all teeth were asymptomatic but reacted negatively on carbon dioxide snow and electrical pulp testing. All teeth that underwent a REP showed complete PBH and further RD on PR and CBCT assessments when comparing the baseline with the final recall radiographs. CBCT analyses indicated increases in root hard tissue volume and RL for all teeth that underwent a REP, but they were 5 and 3 times less, respectively, than the contralateral teeth. The postoperative CBCT images presented bone ingrowth inside the root canal, calcification, or nonuniform RD. ConclusionsThirty-six months after the REPs (based on the cell homing concept), this RCS resulted radiographically and clinically in functional and asymptomatic teeth with complete PBH and continued reparative RD. CBCT quantitative measurements and qualitative root development observations are more reliable and accurate than PR analysis.

Volumetric, Radiographic, and Histologic Analyses of Demineralized Dentin Matrix Combined with Recombinant Human Bone Morphogenetic Protein-2 for Ridge Preservation: A Prospective Randomized Controlled Trial in Comparison with Xenograft

The aim of this study was to evaluate the clinical, volumetric, radiographic, and histologic aspects of autogenous demineralized dentin matrix (DDM) combined with recombinant human bone morphogenetic protein-2 (rhBMP-2) used for ridge preservation, compared to those of deproteinized bovine bone with collagen (DBBC). Following atraumatic extraction, the socket was filled with DBBC, DDM, or rhBMP-2/DDM. Scanned images of dental casts and cone beam computed tomographs (CBCT) were superimposed for the calculation of soft and hard tissue volume alteration. Preoperative and postoperative measurements of the height and width of the alveolar ridge were compared using CBCT images. After 4 months, bone specimens were harvested for histomorphometric assessment. Loss of hard and soft tissue volume occurred at 4 months after extraction and ridge preservation in all groups. No volumetric differences were detected among the three groups before and 4 months after ridge preservation. The reduction in the horizontal width at 5 mm was higher in the DBBC compared to the DDM. Histologically, approximately 40% newly formed bone was founded in rhBMP-2/DDM group. The autogenous dentin matrix used to fill the socket was as beneficial for ridge preservation as conventional xenografts. The combination of rhBMP-2 with dentin matrix also demonstrated appreciable volumetric stability and higher new bone formation compared to DDM alone and DBBC.

Randomised Controlled Clinical Trial Investigating The Impact of Implementation Planning on Behaviour Related to The Diet

There is a perceived gap between dietary advice given by health practitioners and adherence to the advice by patients. We investigated whether a behaviour change technique (implementation-planning) was more effective than standard-of-care diet advice at reducing dietary acid intake using quantitative erosive tooth wear progression as an objective clinical outcome. This study was a randomised controlled, double-blind, single-centre clinical trial in the UK. Participants (n = 60) with high dietary acid intake (≥2 daily), were recruited and randomly assigned (1:1) to receive either implementation-planning or standard-of-care diet advice in a single clinical session. Questionnaires and impressions were taken at baseline and 6 months later. Dental casts were scanned using laser profilometry and superimposed using surface-matching software. Data were analysed per protocol and intention-to-treat using independent t-tests and Mann-Whitney tests. The intervention group reduced their dietary acid intake between meals to 1 intake per day compared to 2 intakes per day for the controls and demonstrated reduced dental hard tissue volume loss (−0.00 mm3 (SD = 0.01)) compared to controls (−0.07 mm3 (SD 0.17)), p = 0.049. This paper supports the use of implementation planning in clinical practice and presents a non-invasive method of intervention assessment in behaviour change. Larger trials are needed to confirm the generalisability of results.

Hard tissue augmentation to minimize a risk of buccal gingival recession in lower anterior teeth associated with orthodontic treatment: case report

Patients with malocclusion may present with preexisting mucogingival problems susceptible to attachment loss during or after orthodontic treatment. Lower anterior teeth especially show a high prevalence of gingival recession following orthodontic treatment. This case report demonstrates hard tissue augmentation of labially thin or deficient alveolar bone (dehiscences and fenestrations) to prevent attachment loss during or after orthodontic treatment. Three patients presented clinically prominent root surfaces and dehiscences and fenestrations on cone-beam computed tomography (CBCT) in lower anterior teeth. Labial hard tissue augmentation of lower anterior teeth was performed with deproteinized bovine bone mineral and collagen membrane. Six months later, hard tissue augmentation reduced root prominence and created a greater volume of hard tissue on lower anterior area in clinical and radiographic findings. Hard tissue augmentation using xenograft could prevent attachment loss associated with orthodontic treatment and maintain stability of healthy periodontium.

Direct Linear Measurement of Root Dentin Thickness and Dentin Volume Changes with Post Space Preparation: A Cone-Beam Computed Tomography Study.

Aim:The purpose of the present study was direct linear measurement of dentin thickness and dentin volume changes for post space preparation with cone-beam computed tomography (CBCT).Materials and Methods:Ten maxillary central incisors were scanned, before and after root canal and post space preparation, with Orthophos XG three-dimensional hybrid unit. Thirteen axial section scans of each tooth from orifice to apex and dentin thickness for buccal, lingual, mesial, and distal were measured using proprietary measuring tool and thereafter subjected to statistical analysis. Furthermore, dentin volume was evaluated using ITK-SNAP software.Results:There was statistically significant difference between the dentin thickness in pre- and postinstrumentation (paired t-test) and also between different groups (one-way ANOVA). In the shortest post length of 4.5mm the post space preparation resulted in 2.17% loss of hard tissue volume, where as 11mm longest post length post space preparation resulted in >40% loss of hard tissue volume.Conclusion:CBCT axial section scan for direct measurements of root dentin thickness can be guideline before and after post space preparation for selection of drill length and diameter.

Hard tissue volume stability of guided bone regeneration during the healing stage in the anterior maxilla: A clinical and radiographic study.

Guided bone regeneration (GBR) is currently the most widely used technique to reconstruct localized peri-implant bone defects. To evaluate hard tissue volume stability during the healing stage of GBR with particulate bone graft and resorbable collagen membrane. Twenty-eight patients who were missing a single maxillary incisor and required implant placement combined with GBR were randomly assigned to 2 groups: submerged (n = 14) and transmucosal (n = 14) healing groups. Cone-beam computed tomography (CBCT) was performed before, immediately after and 6 months post-surgery. The 3 sets of CBCT data were three-dimensionally reconstructed and superimposed. Horizontal hard tissue alterations at different vertical levels were recorded. The relative position and distances from the boundary line of the bony defect envelope to the outlines of the augmented ridge were determined immediately post-augmentation and 6 months after healing. Augmented ridge underwent horizontal volume reduction during the healing period. Vertical levels (P = .000) rather than healing strategies (submerged or transmucosal) (P = .182) had statistically significant impacts on the reduction width. The boundary line of the ridge defect envelope located within the bony profile immediately after surgery, but outside of the bony profile after 6 months. GBR with resorbable membrane and particulate bovine bone would undergo horizontal volume reduction during the healing stage. New bone formation at the coronal site may only be predictable within the bony envelope.

A Semi-automatic Algorithm for Preliminary Assessment of Labial Gingiva and Alveolar Bone Thickness of Maxillary Anterior Teeth.

Soft and hard tissue volumes are critical for implant placement and long-term stability. Although the literature has adequately addressed tissue biotypes of Western populations, pertinent information about Asian populations is limited. This study aimed to evaluate the soft and hard tissue profiles of the maxillary anterior teeth of the Taiwanese population using a semi-automatic algorithm. Cone beam computed tomography images of 11 adults with well-aligned maxillary anterior teeth were overlaid with those of cast models, based on the tooth crowns manually outlined by two independent observers. Each tooth was digitally trisected mesiodistally and apicocoronally. The thicknesses of the labial gingiva and alveolar bone were measured using a customized software program. No obvious difference between the observers was noted regarding the dimension of tooth crowns. The average thicknesses of the labial gingiva, the labial alveolar bone, and the palatal alveolar bone were 1.76 ± 0.11 mm, 1.02 ± 0.12 mm, and 1.80 ± 0.31 mm, respectively, with no significant differences between teeth. All parameters were thicker in the apical region than in the cervical region, and the alveolar bone was thinner in the midlabial region of incisors than in the interproximal regions. The thinnest areas were the midcervical compartment of the right central incisor (0.53 ± 0.33 mm) for the labial gingiva, the midcervical compartment of the right lateral incisor (0.23 ± 0.10 mm) for the labial alveolar bone, and the mesiocervical compartment of the left central incisor (0.33 ± 0.09 mm) for the palatal alveolar bone. This study presents an objective and comprehensive methodology for evaluating the soft and hard tissue profiles of maxillary anterior teeth and may be of value for presurgical planning for immediate implant placement. The results suggest that profiles of the Taiwanese subjects are similar to profiles of Western populations.

The Influence of Force Direction on the Fracture Pattern and Fracture Resistance of Canine Teeth in Dogs.

Biomechanical studies of the elongated canine tooth of animals are few, and thus our understanding of mechanical and physical properties of animal teeth is limited. The objective of the present study was to evaluate the influence of force direction on fracture resistance and fracture pattern of canine teeth in an ex vivo dog cadaver model. Forty-five extracted canine teeth from laboratory beagle dogs were standardized by hard tissue volume and randomly distributed among 3 force direction groups. The teeth were secured within a universal testing machine and a load was applied at different directions based on testing group. The maximum force to fracture and the fracture pattern classification were recorded for each tooth. After correcting for hard tissue cross-sectional area in a multivariate analysis, no significant difference in the amount of force required for fracture was apparent between the different force direction groups. However, the influence of force direction on fracture pattern was significant. The results of this study may allow the clinician to educate clients on possible causal force directions in clinically fractured teeth and, thus, help prevent any contributing behavior in the future.

Hemifacial Microsomia - A Case Report With Review Of Literature

Hemifacial microsomia (HFM) is a congenital deformity characterised by unilateral deficiency in the volume of hard and soft tissue of face. It is a syndrome predominantly affecting first branchial arch featuring poorly developed temporomandibular joint, mandibular ramus, muscles of mastication and ear. People with HFM may present with an underdeveloped ear (microtia) or absent ear (anotia) on the affected side of the face. The incidence of this disorder is 1:3000-26,000, which is usually seen at birth. Here we present a case of hemifacial microsomia in a 12-year-old girl with hearing difficulties on the affected side with review of literature.

Mandibular bone regeneration after bone slat technique.

The reconstruction of alveolar ridges for implant placement is still a challenging surgical procedure, especially in the case of extensive vertical and horizontal bone atrophy. The objective of the present study was to evaluate the quantity and quality of newly regenerated bone; clinically by means of direct clinical measuring, ridges augmented by autogenous cortical bone associated with autogenous particulate bone graft in the posterior lower jaw defect. For the preliminary study, a bone defects in partially edentulous in patient aged 52 years were selected to receive horizontal ridge augumentation prior autolougous bone block and particulate graft. The donor site was the ramus of the same side. Prior the clinical evaluation, periapical X-ray and the cone beam computerized tomography (CBCT) was observed the quality, quantity and the stability the soft and hard tissue healing process, final result and the outcome. The bone augmentation achieved with this technique created the ideal bone volume of hard and soft tissue, in quantity and quality, for placement of implants. The surgical technique was found to be easy in terms of technique and surgical trauma.

Minimally Invasive Implantology: Flapless Surgery

In conventional implant surgery, the elevation of a muco periosteal flap can facilitate implant placement by allowing the surgeon to visually assess bone quantity and morphology at the site. In cases with limited amount of bone, a flap elevation can help implant placement to reduce the risk of bone fenestrations or perforations over the past three decades there have been several alterations to this flap design in favor of flapless implant surgery which has gained popularity among surgeons. Recently, the Concept of flapless implant, where the implant is placed without reflecting a flap, has gained popularity among surgeons. It has been introduced for the patients with sufficient keratinized gingival tissue and bone volume in the implant recipient site and the size of the surgical field corresponds therefore to the implant diameter. As peri implant tissues management is a challenge, this procedure minimizes the possibility of postoperative periimplant tissue loss [1-3]. It has numerous advantages, including preservation of circulation, soft tissue architecture, and hard tissue volume at the site; decreased surgical time; improved patient comfort; and accelerated healing. It allows also the patient to resume normal oral hygiene procedures immediately after the surgery. A disadvantage of this technique is that the true topography of the underlying available bone cannot be observed, which may increase the risk for unwanted perforations. In addition, it can lead to esthetical problems or implant losses [4]. Moreover, there is the potential for thermal damage secondary to reduced access for external irrigation during osteotomy preparation. The successful use of this approach often requires advanced clinical experience and surgical judgment [4-6]. References

A new age estimation procedure based on the 3D CBCT study of the pulp cavity and hard tissues of the teeth for forensic purposes: A pilot study

BackgroundDental age of adults can be estimated by the analysis of the progressive physiological and degenerative phenomena which affect dental tissues. The pulp-dentinal complex is one of the dental structures that show modifications related to age, mainly resulting in the reduction of the pulp chamber volume due to the continual deposition of secondary dentin. The study aims to evaluate the accuracy of a simple and conservative method for estimating the age of adults based on CBCT (Cone Beam Computed Tomography) analysis of the narrowing of the pulp chamber caused by secondary dentin deposition. Materials and methodsTwo operators have randomly analyzed 148 CBCT (Scanora 3D – Soredex) and considered the upper left central incisor. The sample consists of 57 male individuals and 91 females aged between 10 and 80 years. This research was designed to simplify dental volume measurement through geometric approximation of the different parts of the tooth. The root and the pulp were assimilated to elliptical based cones and the crown to an elliptical based truncated cone and these volumes were calculated through measurements using Osirix® software (OnDemand 3D software CyberMed Inc.). The ratio between the pulp volume and the hard tissues volume (PHr) was assumed as a variable according to the following formula: PHr = V pulp/V ht. The proposed method based on geometric approximation of dental volumes was validated comparing volumes calculated using CBCT with physical measurements of real volumes of 3 teeth. ResultsThe physical measurements revealed that the measurement procedures using CBCT produce a regular underestimation of real volumes, that ranges from 53% to 70%. Since the error occurs quite regularly both for pulp and for hard tissue volume, it tends to be eliminated when their ratio is considered. The PHr was statistically significant (p-value < 0.001) as a predictor for age estimation. The gender variable was not significantly correlated with age (p = 0.7694) and it was, therefore, excluded from the linear regression formula for age estimation: Age = −64.14 – 32.00*Ln PHr. The age cohorts between 30 to 59 years showed the highest accuracy in age prediction (residual errors 0.71, 2.88, and −5.86 years), whilst for other age cohorts the estimation error is similarly reported by applying other dental methods. ConclusionThe outcomes of this pilot study show that the narrowing of the pulp chamber is a reliable parameter for estimating the age of adults, and that CBCT is an easy and conservative approach that allows accurate calculation of tooth volumes. The proposed approach based on geometric approximation of upper central incisor volumes measured by CBCT remarkably reduced the operating time in comparison to other more complex and expensive techniques. The validation procedure in which real volumes are compared with those calculated using CBCT supports the accuracy of the experimented approach and the good inter-examiner agreement (ICC 0.99) demonstrates that the method is highly reproducible.

The Influence of Crown Height to Diameter Ratio on the Force to Fracture of Canine Teeth in Dogs.

Previous work suggests that the tooth height to diameter ratio (H/D) may have an influence on the fracture resistance of dog canine teeth. Thus, it can be hypothesized that canine teeth with distal abrasion or teeth already requiring pulpal manipulation may benefit from a reduction in height and that an ideal H/D exists that balances tooth fracture resistance and tooth function. Therefore, a study was performed to investigate the influence of H/D on force to fracture and probability of fracture of canine teeth in dogs. Thirty extracted canine teeth from laboratory Beagle dogs were standardized by hard tissue volume and evenly distributed among three groups; unaltered H/D (group A), 10% reduction in H/D (group B), and 20% reduction in H/D (group C). The teeth were potted in clear autopolymerizing orthodontic acrylic and then secured within a universal materials testing machine. A displacement was applied at a speed of 1-mm/min to the distoocclusal line angle at an angle of 45 degrees to the long axis of the crown. The maximum measured force at the time of fracture represented the maximum force to fracture. A linear regression model showed a significant inverse relationship between H/D and force to fracture (p = 0.043; 95% CI-55.2 to -0.09). A margin of safety (MoS) analysis was performed to determine the probability of fracture by comparing normal force distributions of the measured force at fracture to that reported in a previous study, representative of normal biting-pulling loads on canine teeth. When 100% of the load was applied to a single unaltered canine tooth the probability of fracture was 36.7%. Decreases in H/D of 10% and 20% resulted in a decreased probability of fracture by 24.1% and 60.4%, respectively. A paired MoS analysis was conducted wherein the applied loads were distributed across 2 maxillary canine teeth according to their relative heights. Within the pair, a 20% decrease in H/D decreased the probability of fracture of that tooth by 86.5%, but increased the probability of fracture of the unaltered contralateral canine tooth by 54.4%. The findings of this study support the hypothesis that teeth with a lower H/D are more resistant to fracture. However, given the potential impact of crown reduction of a single canine tooth on the load redistribution to the remaining unaltered canine teeth, further investigation is needed to determine what H/D would be ideal. In addition, future studies could elucidate in which clinical scenarios the concept of H/D reduction could be implemented. The results of this study may have implications on the successful long-term management of traumatized canine teeth in dogs.