Loss Of Vertical Height Research Articles

Factors influencing further vertebral height loss following percutaneous vertebroplasty in osteoporotic vertebral compression fractures: A 1-year follow-up study.

Osteoporotic vertebral compression fractures (OVCFs) contribute to back pain and functional limitations in older individuals, with percutaneous vertebroplasty (PVP) emerging as a minimally invasive treatment. However, further height loss post-PVP prompts investigation into contributing factors. To investigate the factors associated with further height loss following PVP with cement augmentation in OVCF patients. A total of 200 OVCF patients who underwent successful PVP between January 2021 and December 2022 were included in this study. "Further height loss" during 1 year of follow-up in OVCF patients with bone edema was defined as a vertical height loss of ≥ 4 mm. The study population was divided into two groups for analysis: The "No Further Height Loss group (n = 179)" and the "Further Height Loss group (n = 21)." In comparing two distinct groups of patients, significant differences existed in bone mineral density (BMD), vertebral compression degree, prevalence of intravertebral cleft (IVF), type of bone cement used, and cement distribution patterns. Results from binary univariate regression analysis revealed that lower BMD, the presence of IVF, cleft distribution of bone cement, and higher vertebral compression degree were all significantly associated with further height loss. Notably, the use of mineralized collagen modified-poly(methyl methacrylate) bone cement was associated with a significant reduction in the risk of further height loss. In multivariate regression analysis, lower BMD and the presence of IVF remained significantly associated with further height loss. Further height loss following PVP in OVCF patients is influenced by a complex interplay of factors, especially lower BMD and the presence of IVF. These findings underscore the importance of assessing and managing these factors when addressing height loss following PVP in OVCF patients.

In Vitro Analysis of Bonding and Wear Properties of 3D Printed Denture Tooth Materials.

While additive manufacturing (3D printing) has recently enhanced removable prosthodontics, the properties of new 3D printed materials are not well understood. This study aims to elucidate the physical properties of these materials, focusing on bonding to a 3D printed denture base material and wear resistance. For denture tooth-denture base bonding analyses, the same denture tooth material (Premium Teeth, Formlabs) was used with three denture base-bonding group assignments (n=6 each group) bonded using three protocols: Group A1 was bonded with Lucitone Digital Print-3D Denture Base using the Lucitone Fuse System (Dentsply), Group A2 with Formlabs Denture Base using the Formlabs Denture Base Bonding System, and Group A3 with Formlabs Denture Base using the Ivoclar Ivotion Bonding System (Ivoclar). Specimens were made according to the ISO-TS-19736-2027 standard. A 3D printed tooth mimicking a central incisor was bonded to the denture base and subjected to a palatal load at the incisal region at 90° from the long axis of the tooth until failure. The fracture surface was examined at 10× magnification. ANOVA with α=0.05 was used to determine statistically significant differences. For wear analysis, the same denture base material and bonding system (Lucitone Digital Print-3D Denture Base/Lucitone Fuse System, Dentsply) was used with four denture tooth material group assignments (n=8 each group): Group B1 used Formlabs Premium Teeth, Group B2 used SprintRay High Impact Denture Teeth, Group B3 used Lucitone Digital IPN Premium Tooth, and Group B4 used Ivotion Polymethyl Methacrylate (PMMA) Milled Teeth (Ivoclar). A premolar denture tooth bonded with the denture base was subjected to a chewing simulation cyclic loading of 1,200,000 cycles. Sample failures, vertical wear, and volume loss were documented. ANOVA with α=0.05 was used to determine statistically significant differences. The fracture load to failure values for A1, A2, and A3 were 175±106 N, 167±46.3 N, and 183±48.9 N, respectively (p=0.95). Most failure characteristics were mixed, except one of A2 was cohesive and half of A3 was cohesive. For cyclic loading, B4 was the only group where all specimens failed within 1,200,000 cycles, while B1, B2, and B3 had four, three, and five sample failures, respectively. Vertical wear was 0.93±0.34 mm, 1.22±0.37 mm, 1.05±0.27 mm, and 0.37±0.02 mm for B1, B2, B3, and B4, respectively (p<0.01). Abrasion volumes were 9.5±3.7 mm³, 12.2±4.7 mm³, 10.6±3.5 mm³, and 2.2±1.3 mm³ for B1, B2, B3, and B4, respectively. Vertical height loss per chewing cycle (μm/cycle) was 0.0022±0.0019, 0.0030±0.0029, 0.0012±0.00005, and 0.0080±0.0050 for B1, B2, B3, and B4, respectively (p<0.01). Abrasion volume per chewing cycle (μm³/cycle) was 17650.8±9682.9, 27263.4±24746.8, 11836.5±4200.8, and 70436.8±73602.5 for B1, B2, B3, and B4, respectively (p=0.02). The bonding strength and wear resistance of 3D printed denture materials vary by manufacturer. Formlabs Denture Base with Ivoclar Ivotion showed the highest fracture load, indicating superior bonding strength. In wear analysis, Ivoclar Ivotion PMMA Milled Teeth exhibited the least vertical wear and abrasion volume but had the highest failure rate under cyclic loading. While printed denture materials excel in bonding strength, their wear resistance may not be as good as milled denture teeth, highlighting the need to balance these properties in clinical applications.

Wear Behavior of Monolithic Zirconia after Staining, Glazing, and Polishing Opposing Dental Restorative Materials: An In Vitro Study

The purpose of this in vitro study was to compare the effect of staining, glazing, and polishing on the wear behavior of stabilized zirconia with 5 mol% of yttrium oxide (5Y-TZP) opposing 5Y-TZP, leucite-reinforced ceramic (LC), lithium disilicate (LD), and microhybrid composite resin (MCR). Hemispheres of 5Y-TZP were divided into six groups (n = 10) according to the finishing procedure: C (control), S (staining), G (glazing), P (polishings), SG (staining plus glazing), and SP (staining plus polishing). The two-body wear test (2BW) was performed (20 N load, at 2 Hz, until 300,000 cycles). Vertical height loss of hemispheres (VHL) and wear depth of restorative materials (WD) were analyzed using a profile projector and laser confocal microscope, respectively. Data of VHL and WD were analyzed using a generalized linear model by the Wald test and t post hoc test with the Bonferroni adjustment (α = 0.05). The staining, glazing, polishing, and restorative material had a significant effect (p &lt; 0.05) on VHL and WD. Polishing reduced VHL opposing MCR, LC, and LD. There was an increase in WD to G opposing LD and SG opposing MCR. The 5Y-TZP presented the highest wear resistance, while MCR presented the lowest. Polishing was recommended to promote staining durability and decrease wear rates opposing MCR and LD.

Wear and surface roughness of commercially available computer-aided design/computer-aided manufacturing dental ceramic materials

The study evaluated in vitro two-body wear and surface roughness of the recently introduced CAD/CAM dental materials. Pin-on-disk design was set against each other horizontally at a fixed distance with 5 kg (49 N) in distilled water. CAD/CAM materials used were: Feldspathic ceramic (Vitablocks Mark II), lithium disilicate (IPS e.max CAD), hybrid ceramic (Vita Enamic) and zirconia-reinforced glass ceramic (Vita Suprinity PC). Wear evaluation before and after the chewing cycles were performed by two approaches: weight and vertical height measurements. The surface roughness of the tested materials was further evaluated after chewing cycles. One-way ANOVA showed significant differences among the mean values of the materials’ vertical height loss and surface roughness (P &lt; 0.05). However, in weight loss, no statistical differences were observed. The highest vertical height loss was observed in feldspathic ceramic while the lowest vertical height loss was recorded in zirconia-reinforced glass ceramic. Feldspathetic ceramic demonstrated the least surface roughness among all the groups. Feldspathic ceramic had a significantly least wear resistance and surface roughness, while Zirconia reinforced glass ceramic (VITA Suprinity PC) had a significantly higher wear resistance and acceptable surface roughness among tested groups.

Comparing open and closed treatment strategy in adult patients with condylar head fractures. What is associated with a better functional outcome?

IntroductionIntracapsular condylar fractures are an important component of craniofacial trauma. The indication for open repair has been historically controversial. A review of the literature was performed to compare functional outcomes of open vs closed treatment strategies of condylar head fractures, as well as to identify indications for operative management.Few systematic reviews have been conducted specifically addressing condylar fractures, however none to our awareness specifically address the condylar head fracture. MethodA literature review was designed and implemented to evaluate the functional outcomes and indications for open reduction of condylar head fractures versus closed treatment. A comprehensive electronic search of studies published between 2001 and 2021 of adult patients with condylar head fractures was conducted. ResultsThe literature review identified 18 articles that met the inclusion criteria. The majority of studies showed improved functional outcomes in the open reduction group with regards to maximal interincisal opening, excursive movements, deviation of midline, malocclusion, ankylosis, and chronic pain. Indications for operative management of condylar head fractures vary, however ramus shortening with loss of vertical height seems to be the prevalent indication. ConclusionThere is not yet one overriding consensus dictating management of condylar head fractures. It appears more and more studies are supporting the idea that better functional outcomes (and quicker return to function) are achievable using an open reduction strategy. However, closed treatment remains a valid option in some cases. Therefore, the most appropriate treatment must still be personalised to the individual patient.

Wear analysis and topographical properties of monolithic zirconia and CoCr against human enamel after polishing and glazing procedures

PurposeIntraoral adjustments of monolithic zirconia (MZ) necessitate intraoral grinding and polishing procedures, causing surface topography changes. The effect of various polishing and glazing procedures on surface roughness, topographical and phase changes of CoCr compared to zirconia, and assessment of the wear of the opposing dentition has been evaluated in this study. Materials and methodsOne group of square Cobaltchromium (CoCr) and four groups of sintered and polished zirconia specimens (12 × 12 × 1mm) were fabricated (N = 5, n = 8) using Cobaltchromium or yttria-stabilized zirconia (ZrO2, Y2O3) blocks (ZENTROSTAR Zr Translucent; Wieland Dental + Technik). Each of the four zirconia groups was treated differently, one group was glazed (G), one was left unglazed (UG), two groups were polished, one using silicon carbide polishers (BG) and one with diamond-impregnated ceramic polisher kit (CG). All specimens were thereafter subjected to chewing simulation using enamel cusps (1’200’000 cycles, 49N force and 1.67 Hz loading frequency). Topographical changes were evaluated considering (a) weight (digital scale), (b) volume loss (digital microscope), (c) vertical height loss (digital microscope), (d) surface roughness (Ra, profilometer), and (e) mean roughness depth (Rz, profilometer). In addition the volume loss (digital microscope) of the used corresponding enamel cusps was measured. The surface roughness, topographical changes and antagonist wear of enamel cusps were measured. Statistical analysis was performed using the statical software R and the kruskal-wallis rank sum test and posthoc pairwise comparisons (a = 0.05). ResultsThe mean surface roughness (μm) difference (ΔRa) was lowest for UG (−0.014 ± 0.007) and the highest for CG (−0.806 ± 0.172) (UGa < CoCrb < BGc < Ga,d < CGe). UG showed the lowest surface peak roughness (μm) difference (ΔRz) −0.316 ± 0.084 and CG the highest (−3.691 ± 0.369) (UGa < CoCrb < BGc < Ga,d < CGe). Material weight loss (ΔW) ranged between −0.005 ± 0.0001 and −0.000 ± 0.000 g (CoCra < UGa,b < CGb < BGb < Gb) compared to baseline, while the volume loss (ΔV) was between −21 ± 52 × 106 and 58 ± 36 × 106 μm3 (CoCra < BGa < UGa < CGa < Ga). The vertical height loss (ΔVH) was highest for UG (−12.067 ± 11.624) and lowest for G −0.033 ± 0.034 μm (Ga < CoCra,b < CGc < BGa,c,d < UGa,b,d). As for the volume loss (ΔV) of the corresponding enamel cusps, no significant differences could be measured (BGa < UGa < Ga < CGa < CoCra), therefore surface treatment did not affect the wear of the enamel antagonist. ConclusionCoCr and highly polished monolitic zirconia produced less surface roughness and similar antagonist wear compared to glazed or unglazed zirconia. CoCr and highly polished monolitic zirconia can be considered as a good choice regarding the mechanical wear behaviour of materials and their corresponding enamel antagonist.

Fresh Frozen Allogeneic Bone Block in Maxillary Sinus Floor Elevation: Histomorphometric Analysis of a Bone Specimen Retrieved 15 Years after Grafting Procedure

Nowadays implant-prosthetic rehabilitations are one of the best solutions for rehabilitating our patients. These allow obtaining rehabilitations with optimal functional and aesthetic performances. Often patients, who undergo implant-prosthetic therapy, have the conditions of edentulias, single or multiple, that have been going on for some time. This, according to the literature, produces resorption of the alveolar bone, a process that is complicated in the posterior area of the upper arch by a pneumatization of the maxillary sinuses. The loss of vertical height, so that the implant fixtures can be inserted, requires a maneuver called maxillary sinus floor elevation. This procedure, now safely performed with piezoelectric instruments, allows increasing bone height through bone grafting. In this study, the tissue obtained from a patient, after 15 years from the intervention, was evaluated by histological and SEM analyses. The bone healing in the patient has led to a perfect integration between the patient’s bone and the fresh frozen allograft used, however still present and detectable after 15 years.

Sinteza PMMA/ZnO nanodelcev kompozitov za izdelavo zob iz umetnih smol

Wear resistance is one of the most important physical properties of the artificial teeth used in acrylic dentures. The goal of this research was to synthesize a new composite material made of matrix Poly-(methyl methacrylate)-PMMA with different percentages (2 % and 3 % of volume fractions) of zinc-oxide nanoparticles (ZnO NPs) as reinforcing elements, to improve its mechanical properties. The dynamic mechanical behaviour of this composite was studied through the DMA method in comparison to the pure PMMA supported by the characterization of their microstructures. Then the wear resistance was analysed on the samples, which were prepared in the form of teeth. In this context their vertical height loss was measured after 100,000 chewing cycles on a chewing simulator, before and after the artificial thermal ageing. Investigations showed that the PMMA/ZnO NP composites dampened the vibrations better than the pure PMMA, which could be assigned to the homogenous distribution of ZnO NPs in the PMMA matrix. It was found that the mean vertical height loss for the pure PMMA teeth was significantly higher (more than 4 times) compared to composite teeth made with ZnO NPs. Introducing the thermal artificial ageing led to the finding that there was no effect on the height loss by the composite material with 3 % of volume fractions of ZnO NPs. Based on this it was concluded that PMMA/ZnO NPs composites showed improved in-vitro wear resistance compared to acrylic-resin denture teeth, so this new composite material should be preferred when occlusal stability is considered to be of high priority.

Kiefergelenkfortsatzfrakturen nach der AO-CMF-Trauma-Klassifikation

Im Prazisionslevel 3 der AO-CMF-Trauma-Klassifikation werden Kiefergelenkfortsatzfrakturen in Frakturen des Gelenkkopfs (Walze, Capitulum), des Gelenkhalses und der Gelenkfortsatzbasis unterteilt. Kopffrakturen weisen 2 typische Bruchverlaufe auf. Bei einer Fraktur im medialen Walzenbereich (Frakturtyp m) bleibt die Relation lateraler Kondylus zu Fossa und Diskus i.d.R. erhalten. Eine Fraktur im Bereich des lateralen Walzenpols (Frakturtyp p) ist ublicherweise mit einem Hohenverlust assoziiert; der Diskus mit dem kleinen (proximalen) Fragment wird nach anteromedial disloziert, was mit oder ohne Verletzung des lateralen Kapselansatzes einhergehen kann. Die Frakturmorphologie wird neben dem Hohenverlust durch die Attribute Fragmentation („minor“, „major“), vertikale Fragmentapposition sowie Dislokation, Luxation und Distorsion des proximalen Fragments in Bezug auf die Fossa naher definiert. Gelenkfortsatzbasis- und Gelenkhalsfrakturen werden gemas einer neuen Ein-Drittel- zu Zwei-Drittel-Regel fur den Frakturverlauf ober- bzw. unterhalb der sog. Loukota-Linie („sigmoid notch line“) differenziert. Attribute zur Definition der Morphologie sind auch hier das Vorliegen einer Luxation oder Dislokation und deren Richtung, die Angulation des gelenktragenden Fragments und Parameter wie Fragmentation, Hohenverlust und Dislokationen in der Kondylus-Fossa-Relation.

“Closed Reduction” Principles Can Manage Diverse Conditions of Temporomandibular Joint Vertical Height Loss: From Displaced Condylar Fractures to Idiopathic Condylar Resorption

The aim of this case series was to describe a modification of the classic "closed reduction" technique to manage unilateral or anterior open bite owing to a loss in vertical height (LVH) caused by several disorders and pathologies other than displaced condylar fractures. The protocol included insertion of an occlusal appliance to increase the height of the premature contact and the width of the open bite, stabilization of the dental arches by rigid arches, and the use, during sleep, of rubber bands in the open bite region to pull the mandible cranially. In addition, when awake, the patient performed physiotherapy exercises to guide the mandible into maximum intercuspation. The increased open bite enhanced the effect of the rubber bands in guiding the mandible into the original habitual occlusion and the rigid arches served to minimize tooth eruption. The present cases showed the favorable outcome of this low-risk treatment in the re-establishment of the original habitual occlusion within 1 to 4weeks and without reconstruction of the LVH. The efficacy of this complication-free approach to correct occlusion in various conditions of LVH suggests that this protocol should be applied before venturing into surgical intervention.

Wear resistance and compression strength of ceramics tested in fluoride environments

Dental ceramics have been widely used because of aesthetic, but wear is still questioned. There are relates that ceramic surface is prone to degradation by acidulated fluoride, that can increase wear rates. The aim of this study was to evaluate the effect of neutral and acidulated fluoride gel, used as preventive agents for professional use, at wear and compression strength of dental ceramics IPS e.max ZirPress (ZIR), IPS Empress Esthetic (EMP) e IPS Inline POM (POM). For this, 30 crowns and 30 disks were obtained by heat-pressing. Crowns and disks were submitted to two-body wear test at machine of mechanical loading, simulating occlusion, lateral movement and disocclusion. It was performed 300,000 cycles at 1Hz frequency under 20N load, to simulate 1 year of mastication. Samples were totally immersed during the test and were divided into three groups according to the gel used for immersion (n=10): control, neutral (sodium fluoride 2%) and acidulated (acidulated phosphate fluoride 1.23%). Samples (crowns and disks) were analyzed for vertical height loss after the test using, respectively, profile projector and stereomicroscope. Roughness of worn surface of crowns and disks was evaluated by laser confocal microscopy. Data of height loss and roughness were evaluated by two-way ANOVA and Bonferroni's test. A crown/disk of each group was analyzed by scanning electronic microscopy. After wear resistance tests, crowns were cemented to their abutments and submitted to compressive load at 30° angulation and 1mm/min speed. Type of failures was compared by qui-square test. Ceramic EMP worn less while ZIR worn more. Control gel worn more at crowns while acidulated gel worn more at disks. Surface roughness of samples tested at acidulated gel was significantly lower. Type of failures found at compression resistance tests was affected by ceramic type, but not by gel used. The results suggest that ceramic and fluoride gel affect wear and roughness of worn surface while type of failure is only affected by ceramic.

Residents' journal review

Residents' journal review

Mandibular Ridge Augmentation Using a Mineralized Ilium Block: A Case Letter

Mandibular Ridge Augmentation Using a Mineralized Ilium Block: A Case Letter

The Comprehensive AOCMF Classification System: Condylar Process Fractures - Level 3 Tutorial.

This tutorial outlines the detailed system for fractures of the condylar process at the precision level 3 and is organized in a sequence of sections dealing with the description of the classification system within topographical subdivisions along with rules for fracture coding and a series of case examples with clinical imaging. Basically, the condylar process comprises three fracture levels and is subdivided into the head region, the condylar neck, and the condylar base. Fractures of the condylar head show typical fracture lines either within the lateral pole zone, which may lead to loss of vertical height, or medially to the pole zone, with the latter ones usually not compromising the vertical condyle to fossa relation. In condylar head fractures, the morphology is further described by the presence of minor or major fragmentation, the vertical apposition of fragments at the plane of the head fracture, the displacement of the condylar head with regard to the fossa including a potential distortion of the condylar head congruency resulting in dystopic condyle to fossa relations and the presence or absence of a loss of vertical ramus height. A specific vertical fracture pattern extending from the head to the neck or base subregion is considered. Fractures of the condylar neck and base can be differentiated according to a newly introduced one-third to two-thirds rule with regard to the proportion of the fracture line above and below the level of the sigmoid notch, which is presented in the classification article, and are basically subdivided according to the presence or absence of displacement or dislocation. In both condylar neck and base fractures, the classification is again based on the above mentioned parameters such as fragmentation, displacement of the condylar head with regard to the fossa, including dystopic condyle to fossa relations and loss of vertical ramus height, that is, according to the measurement of the condylar process. In addition, the classification assesses a sideward displacement including the respective displacement sector at the neck or base fracture site as well as the angulation of the superior main fragment and also considers a potential displacement of the caudal fragment with regard to the fossa, which may occur in fractures affecting additional fracture locations in the mandible. The design of this classification is discussed along with a review of existing classification systems. The condylar process for fracture location was defined according to the level 2 system presented in a previous tutorial in this special issue.

Anatomical and Functional Recovery of Intracapsular Fractures of the Mandibular Condyle: Analysis of 124 Cases after Closed Treatment.

Purpose:The purpose of this study is to evaluate the influence of intracapsular fracture lines of the mandibular condyle on the anatomical and functional recovery after non-surgical closed treatment.Methods:Clinical and radiological follow-up of 124 patients with intracapsular fractures of the mandibular condyle was performed after closed treatment between 2005 and 2012. The intracapsular fractures were classified into three categories: type A (medial condylar pole fracture), type B (lateral condylar pole fracture with loss of vertical height) and type M (multiple fragments or comminuted fracture).Results:By radiological finding, fracture types B and M lost up to 24% vertical height of the mandibular condyle compared to the height on the opposite side. In Type M, moderate to severe dysfunction was observed in 33% of the cases. Bilateral fractures were significantly associated with the risk of temporomandibular joint (TMJ) dysfunction in fracture types A and B. Bilateral fracture and TMJ dysfunction were not statistically significantly associated in type M fractures.Conclusion:Most of the mandibular intracapsular condylar fractures recovered acceptably after conservative non-surgical treatment with functional rehabilitation, even with some anatomical shortening of the condylar height. The poor functional recovery encountered in type M fractures, especially in cases with additional fracture sites and bilateral fractures, points up the limitation of closed treatment in such cases.

Efficacy and safety of vertebral stenting for painful vertebral compression fractures in patients with metastatic disease

Background and Purpose:Painful vertebral compression fractures in cancer patients reduce quality of life and may limit survival. We assessed pain relief, vertebral height restoration, and kyphosis correction following vertebral augmentation using a novel expandable titanium stent implant in cancer patients with painful vertebral compression fractures.Materials and Methods:Patients >18 years of age with metastatic disease who presented symptomatic compression fractures of vertebral bodies T5–L5, with or without a history of osteoporosis, were included in the study. Back pain at presentation, immediately after vertebral stenting, and at 1-, 3-, 6-, and 12-month follow-up was estimated using the visual analog scale (VAS). Vertebral height and local kyphotic angle (alpha angle) were measured on lateral standing X-ray before and 1–3 months after stenting.Results:Forty-one cancer patients with painful vertebral compression fractures underwent vertebral stenting procedures at 55 levels. There was no perioperative mortality and no significant complication. Median preoperative VAS was 8·0 (range 8–10), falling to 2·0 immediately postop (range 1–6, P = 0·000) and 0 at all subsequent follow-up (P ≤ 0·012). Mean preoperative vertical height loss was 25·8% (range 0–84·0%) versus a postoperative mean of 18·0% (range 0–66·0%, P = 0·000). Median pre- and postoperative kyphotic angle improved from 8·3° (range 0·2°–54·0°) to 7·1° (range 0·2°–25·0°, P = 0·000). Wilcoxon signed rank test or student's t-test was used for comparisons.Conclusions:Vertebral augmentation using a novel vertebral stenting system provided immediate and enduring pain relief and improved vertebral height loss and kyphotic angle.

Ridge preservation for implant therapy: a review of the literature.

Healing of the extraction socket after tooth removal involves retention of the blood clot followed by a sequence of events that lead to changes in the alveolar process in a three dimensional fashion. This normal healing event results in a minimal loss of vertical height (around 1 mm), but a substantial loss of width in the buccal-lingual plane (4-6 mm). During the first three months following extraction that loss has been shown to be significant and may result in both a hard tissue and soft tissue deformity affecting the ability to restore the site with acceptable esthetics. Procedures that reduce the resorptive process have been shown to be predictable and potentially capable of eliminating secondary surgery for site preparation when implant therapy is planned. The key element is prior planning by the dental therapist to act at the time of extraction to prevent the collapse of the ridge due to the loss of the alveolus.Several techniques have been employed as ridge preservation procedures involving the use of bone grafts, barrier membranes and biologics to provide a better restorative outcome. This review will explore the evidence behind each technique and their efficacy in accomplishing site preparation. The literature does not identify a single technique as superior to others; however, all accepted therapeutic procedures for ridge preservation have been shown to be more effective than blood clot alone in randomized controlled studies.

Potential Correlation between Statins and Pulp Chamber Calcification

Introduction3-Hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) are the first-line pharmaceuticals for the prevention and treatment of dyslipidemia. A recent investigation has shown that statins induced odontoblastic differentiation of dental pulp stem cells. Statins enhance the differentiation of human dental pulp cells by up-regulating mineralization nodules and odontogenic markers. This study tested the hypothesis that the systemic administration of statins results in increased dental pulp calcification. MethodsThis retrospective case-control study used digital bitewing radiographs of mandibular molars. Subjects (N = 90) aged ≥60 years were assigned to either test (n = 45) or control (n = 45) groups based on the systemic use of statins. The dimensions of the pulp chambers were measured using a standardized method for height and mesiodistal distances. The chi-square test was used to analyze the data. Multiple linear regression model analysis was performed to explore the association between statin intake and pulp calcification. ResultsThree of the 45 mandibular molars in the test group exhibited almost complete pulp chamber obliteration. There was a significant reduction in pulp chamber height ratio shown in the statin group compared with the control group (P < .0001). When the mesiodistal width was compared between the 2 groups, there was no significant difference (P = .3730). ConclusionsThe significant increase of calcification and loss of vertical height of the pulp chamber observed in mandibular molars in patients on statin medication indicated a possible increased odontoblastic activity. Therefore, systemic statins could be a contributing factor for pulp chamber calcification.

Effect of thermo-mechanical loading on marginal quality and wear of primary molar crowns

To evaluate the effect of thermo-mechanical loading (TML) on marginal quality and wear of different crown types for primary molars. Eighty extracted human primary molars were used. After preparation, five groups received different crowns (n=16): preformed metal crowns (3M ESPE) and NuSmile crowns (Orthodontic Technologies Inc.) were inserted as preformed metal crowns; as semi-preformed crowns Protemp crowns (3M ESPE) were luted; and as individually manufactured resin composite crowns Filtek Z250 (3M ESPE) and Heliomolar (Ivoclar Vivadent) were used. Specimens were subjected to 2,500 thermal cycles between 5-55(o)C and chewing simulation for 100,000 cycles at 50N at a frequency of 0.5 Hz. Before and after thermo-mechanical loading, impressions of the teeth were taken and replicas were made. The replicas received marginal quality evaluation under a SEM at x200 magnification. Occlusal wear was measured as vertical height loss using a 3-D laser scanning microscope. After TML, all crowns were intact. The adhesively bonded crowns showed significantly better marginal quality to dentine/cementum compared with GIC luted crowns (p<0.05). Laboratory made crowns showed a good fit and nearly transition-free margins also after TML. Preformed metal crowns showed the significantly lowest wear rates compared to the resin composites (p<0.05). Among the resin composite groups, Protemp exhibited the most pronounced wear depths (p<0.05). The different crown types under investigation showed a good performance concerning the evaluated parameters marginal quality and wear.

Intervertebral neural foramina deformation due to two types of repetitive combined loading

Background Tissue compression and noxious stimuli are known to elicit pain from neural tissues in the spine. Compression of nerve roots due to decreases in the intervertebral foramina may be caused by posture, sustained loading and disc height loss, herniation, or altered mechanics. It has been established that non-neutral postures combined with repeated loading can cause disc herniations, however information regarding the effect of repetitive axial twist loading is limited. The objectives of this study were twofold; to measure the occlusion of the foramina due to two types of repetitive loading and to investigate whether repetitive combined axial twist loading can contribute to disc injury. Methods Sixteen porcine cervical spine segments (C5/6) were subjected to 1500 N of compression combined with either repetitive flexion–extension motions or 16.4° (Standard Deviation 2.1) of static flexion with repetitive axial twist motions. The foramina pressure was measured bilaterally using plastic tubing and a custom pressure monitoring system. Specimens were loaded until 10,000 cycles were reached or disc herniation occurred. Findings Significantly larger pressure (pre–post difference) developed in the intervertebral foramina of specimens that were repetitively flexed–extended ( P = 0.028) compared to those that were repetitively twisted. All of the flexed–extended specimens herniated, whereas in the twisted specimens five (62.5%) had incomplete herniations, one (12.5%) sustained a facet fracture, and two (25%) had no damage. There was no difference between the loading groups for vertical height loss ( P = 0.994). Interpretation Repetitive loading of flexion–extension motions are a viable pain generating pathway in absence of distinguishing height loss. This information may be useful to consider for the diagnosis and treatment of nerve root compression.