Five-year cephalometric study of mandibular ridge resorption with different posterior occlusal forms. Part I. Denture construction and initial comparison

Current perspectives of residual ridge resorption: Pathological activation of oral barrier osteoclasts

PURPOSE

Tooth extraction is a last resort treatment for resolving pathological complications of dentition induced by infection and injury. Although the extraction wound generally heals uneventfully, resulting in the formation of an edentulous residual ridge, some patients experience long-term and severe residual ridge reduction. The objective of this review was to provide a contemporary understanding of the molecular and cellular mechanisms that may potentially cause edentulous jawbone resorption.

STUDY SELECTION

Clinical, in vivo, and in vitro studies related to the characterization of and cellular and molecular mechanisms leading to residual ridge resorption.

RESULTS

The alveolar processes of the maxillary and mandibular bones uniquely juxtapose the gingival tissue. The gingival oral mucosa is an active barrier tissue that maintains homeostasis of the internal organs through its unique barrier immunity. Tooth extraction not only generates a bony socket but also injures oral barrier tissue. In response to wounding, the alveolar bone socket initiates regeneration and remodeling through coupled bone formation and osteoclastic resorption. Osteoclasts are also found on the external surface of the alveolar bone, interfacing the oral barrier tissue. Osteoclasts in the oral barrier region are not coupled with osteoblastic bone formation and often remain active long after the completion of wound healing, leading to a net decrease in the alveolar bone structure.

CONCLUSIONS

The novel concept of oral barrier osteoclasts may provide important clues for future clinical strategies to maintain residual ridges for successful prosthodontic and restorative therapies.

Molar space closure: To do or not to do?

Missing or compromised permanent molars can complicate orthodontic treatment planning and mechanics. Molar extraction should be considered in appropriate situations, but clinicians must decide between closing and regaining the edentulous space. Several factors should be taken into consideration to achieve appropriate molar space management, such as the need for space, asymmetry, periodontal status, sinus pneumatization, and the terminal molar position. Herein, three sample cases are reported to demonstrate the treatment options for molar space closure and maintenance with these factors taken into consideration during treatment planning. The understanding of mechanics played a crucial role in anchorage preparation and side effect prevention. If the third molar substitution was managed in advance and adequate space between the ramus and third molar was obtained via second molar protraction, the tooth spontaneously erupted in a favorable position without requiring further treatment. This case series can aid clinicians in molar space management. Regardless of whether the space is to be closed or regained, the treatment plan should conform to the patient’s expectations and improve occlusion with minimal side effects and treatment duration.

Comparative evaluation of condylar guidance obtained by three different interocclusal recording materials in a semi-adjustable articulator and digital panoramic radiographic images in dentate patients: An in vivo study

Aim:

The Aim of the study was to evaluate the reproducibility of condylar inclination values obtained using three different interocclusal recording materials in Hanau Wide-Vue semi-adjustable articulator and to compare those values of condylar inclination with panoramic radiographic images.

Settings and Design:

In Vivo Comparative study.

Materials and Methods:

The clinical trial was carried out in the Department of Prosthodontics, M. R Ambedkar Dental College and Hospital, Bengaluru. A total of 30 dentulous subjects aged between 20 and 40 years were selected, without any signs and symptoms of temporomandibular joint disorders. With the help of a custom-made protrusive guide, protrusive records for three materials were made. These records were used for programming the articulator and the respective horizontal condylar inclination (HCI) value, and panoramic radiographs were made. The values obtained were statistically analyzed.

Statistical Analysis Used:

Independent t-test, multiple comparisons using Bonferroni method followed by Analysis of variances (ANOVA) were used.

Results:

Among each pair of groups there exists a significant difference, i.e., the mean condylar inclination (degree) was found to be statistically significant between wax and polyvinyl siloxane (P < 0.01) as well as between wax and polyether (P < 0.01). No significant difference was observed between polyvinyl siloxane and polyether (P > 0.05).

Conclusion:

HCI values differed depending on the type of material employed. The study concluded that the protrusive condylar guidance angles obtained by panoramic radiograph can be used in programming the semi-adjustable articulator and among the materials polyether gave the highest Condylar Guidance values with less variability and wax gave lowest values with greater variation.

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.

A study on the accuracy of horizontal condylar guidance values in edentulous patients using preprosthetic diagnostic radiographs

Context

Determination of horizontal condylar guidance (HCG) by various clinical and radiographic methods was performed by several investigators. If a correlation between HCG values using lateral radiographic tracing and protrusive interocclusal records can be established, the necessity of performing elaborate recording procedures can be eliminated.

Aims

The aim of this study is to evaluate and to compare the correlation between HCG values in edentulous people using the protrusive interocclusal records mounted on a semi-adjustable articulator with the manual tracing of panoramic radiograph and lateral cephalogram.

Materials and Methods

A total of 20 completely edentulous individuals of either sex from 45 to 75 years (mean age 63.15 years) fulfilling the inclusion criteria were included in this in vivo study. In all the participants, HCG angles were determined clinically using protrusive interocclusal records and semi-adjustable articulator after intraoral gothic arch tracing. Radiographically, it was obtained by cephalometric tracing of panoramic radiograph and lateral cephalogram.

Results

The present study shows mean HCG ± standard deviation (SD) of 28.17° ± 5.99° for interocclusal protrusive record while cephalometric tracing method yielded HCG ± SD of 38.95° ± 4.77° and 35.2° ± 4.94° for lateral cephalogram and orthopantomogram, respectively. A statistically significant positive correlation (P < 0.0001) was found among these three methods.

Conclusion

HCG can be successfully determined in edentulous participants by using three aforementioned methods. HCG values from cephalometric tracing of diagnostic radiographs can be used as an adjunct to the clinical method but cannot be used independently for programming a semi-adjustable articulator.

Concepts of occlusion in prosthodontics: A literature review, part II

This series of articles describes about concepts of occlusion in the complete denture, fixed partial denture, and implants. This article discusses about the evolution of different concepts of nonbalanced occlusion and occlusal schemes in complete denture occlusion.

Condylar guidance: correlation between protrusive interocclusal record and panoramic radiographic image: a pilot study

PURPOSE

The purpose of this study was to compare the sagittal condylar angles set in the Hanau articulator by use of a method of obtaining an intraoral protrusive record to those angles found using a panoramic radiographic image.

MATERIALS AND METHODS

Ten patients, free of signs and symptoms of temporomandibular disorder and with intact dentition were selected. The dental stone casts of the subjects were mounted on a Hanau articulator with a springbow and poly(vinyl siloxane) interocclusal records. For all patients, the protrusive records were obtained when the mandible moved forward by approximately 6 mm. All procedures for recording, mounting, and setting were done in the same session. The condylar guidance angles obtained were tabulated. A panoramic radiographic image of each patient was made with the Frankfurt horizontal plane parallel to the floor of the mouth. Tracings of the radiographic images were made. The horizontal reference line was marked by joining the orbitale and porion. The most superior and most inferior points of the curvatures were identified. These two lines were connected by a straight line representing the mean curvature line. Angles made by the intersection of the mean curvature line and the horizontal reference line were measured. The results were subjected to statistical analysis with a significance level of p < 0.05.

RESULTS

The radiographic values were on average 4° greater than the values obtained by protrusive interocclusal record method. The mean condylar guidance angle between the right and left side by both the methods was not statistically significant. The comparison of mean condylar guidance angles between the right side of the protrusive record method and the right side of the panoramic radiographic method and the left side of the protrusive record method and the left side of the panoramic radiographic method (p= 0.071 and p= 0.057, respectively) were not statistically significant.

CONCLUSION

Within the limitations of this study, it was concluded that the protrusive condylar guidance angles obtained by panoramic radiograph may be used in programming semi-adjustable articulators.

Responses of jawbone to pressure*

OBJECTIVE

To provide a literature review of bone resorption of edentulous jaws focusing on responses to pressure.

BACKGROUND

After the extraction of all teeth in a jaw there is a continuous reduction of the residual ridge. The individual variation of bone resorption is great, and the aetiology is complex and not yet well understood.

MATERIALS AND METHODS

A search of the literature published up to May 2003 on bone resorption and pressure was performed using PubMed/Medline.

RESULTS

Animal studies have demonstrated that excessive and constant pressure induces bone resorption. Recent experimental research has indicated that bone resorption is a pressure-regulated phenomenon with a lower threshold for continuous than for intermittent pressure. Clinical studies have suggested that residual ridge resorption is due more to the effects of denture wearing than to disuse atrophy. However, the results of leaving out dentures at night are not conclusive. Nor does the literature offer any strong evidence for the so-called combination syndrome, which has been described as a result of unfavourable loading. Clinical studies using multivariate analyses indicate that female gender and systemic factors may be of greater importance than oral and denture factors. Implant-supported prostheses have a bone preserving effect rather than the continuing resorption under complete dentures.

CONCLUSIONS

The best way to reduce bone resorption is to avoid total extraction, preserve a few teeth and fabricate overdentures. In edentulous jaws, placement of implant-supported prostheses will lead to less bone loss and may even promote bone growth. To increase our knowledge of residual ridge resorption extended experimental, clinical and statistical methods will be needed, preferably including collaboration between dental and medical researchers.

Post-extraction remodeling of the adult mandible

Following tooth loss, the mandible shows an extensive loss of bone in some individuals. This may pose a significant problem in the prosthodontic restoration of function and esthetics. The many factors which have been proposed as being responsible for the inter-individual variation in post-extraction remodeling mean that a perfunctory analysis of the literature, in which well-controlled, relevant studies are scarce, may not provide the whole story. This article reviews the local and systemic factors which may play a role in the post-extraction remodeling of the mandible. Since severe residual ridge resorption may occur even when the bone status in the rest of the skeleton is good and vice versa, it is concluded that local functional factors are of paramount significance. It is now essential to determine how they can be modified and applied to help maintain ridge height and quality in our aging, edentulous population.

Current perspectives in residual ridge remodeling and its clinical implications: a review

PURPOSE

This article reviews the current understanding of the biology of tooth extraction wound healing and residual ridge remodeling.

METHODS

The review of the biology of tooth extraction wound healing involves a discussion of the different cells populating the tooth extraction wound, the matrix formation, and the control of the repair process in the short-term. Defects in socket matrix formation or cellular activity will lead to stalled healing. The review of residual ridge remodeling describes the long-term result of tooth extraction and formation of residual ridges, in which the quantity of bone tissue continuously decreases. This may suggest that any potential regulatory factors of residual ridge resorption should have an adverse effect either on the increased catabolic activity by osteoclasts or on the decreased anabolic activity by osteoblasts. Both short-term tooth extraction healing and long-term residual ridge remodeling processes are interdependent. Furthermore, any potential genetic and environmental regulatory factors can affect the quality and quantity of bone by altering the gene expression events taking place in bone cells.

RESULTS

The intent of this article was to review the current progresses of biologic research on residual ridge remodeling and to relate the changes at molecular, cellular, and tissue levels. The understanding of residual ridge remodeling may provide a sound scientific basis for improved restorative and therapeutic treatments of the edentulous population.

Clinical morbidity and sequelae of treatment with complete dentures

Wearing complete dentures may have adverse effects on the health of both the oral and the denture-supporting tissues. This article is a review of selected literature on the sequelae of treatment with complete dentures in the specific areas of residual ridge resorption, mucosal reactions, burning mouth syndrome, temporomandibular disorders, and patient satisfaction. Recent literature found with a Medline search from 1952 to 1996 is included in this review. Residual ridge resorption is an inevitable consequence of tooth loss and denture wearing, with no dominant causative factor having been found. Mucosal reactions have a multifactorial cause, most of which can be easily treated. Most patients are satisfied with their complete dentures. Correlations between anatomic conditions and denture quality and patient satisfaction are weak. Psychologic factors seem to be extremely important in the acceptance of and adaptation to removable dentures. There are still no reliable methods to predict the outcome of complete denture treatment and there are many problems related to treatment with complete dentures. Although the prevalence of an edentulous condition is decreasing, the great number of edentulous people warrants the continuing efforts of basic and clinical research on removable partial dentures. Complete denture prosthodontics will remain an important part of dental education and practice. In addition to clinical and technical skills, insight into patient behavior and psychology and communication techniques are also necessary.

The ways and wherefores of immediate placement of implants into fresh extraction sites: a literature review

A waiting period of 12 months or longer to allow total socket healing used to be accepted protocol for placing dental implants. More than 15 years of research and clinical practice were needed for the concept of immediate endossceous implantation into fresh extraction sites to be accepted. Today the dilemma is no longer when, but which, protocol to follow. The diverse recommendations found in the literature leave the practitioner confused as to the methodology of choice. The conclusions drawn after reviewing the relevant literature on immediate dental implantation are: 1) implants placed into fresh extraction sockets have a high rate of survival, ranging between 93.9% to 100%; 2) implants must be placed 3 to 5 mm beyond the apex in order to gain a maximal degree of stability; 3) implants should be placed as close as possible to the alveolar crest level (0 to 3 mm); 4) there is no consensus regarding the need for gap filling and the best grafting material; 5) the use of membrane does not imply better results-on the contrary, membrane exposure may carry complications in its wake; and 6) the absolute need for primary closure remains to be established.

Complete edentulism and denture use for elders in New England

The purpose of this study was to collect information about the oral health of a representative group of elders in the New England states. This study provides the most current descriptive analysis of completely edentulous noninstitutionalized elders to date. In-home examinations and interviews were conducted for a representative sample of elders over 70 years of age. The oral examinations and interviews were conducted by calibrated dentists and trained interviewers, respectively. Of 1156 study participants, 424 (36.7%) were edentulous. Edentulous rates were similar for men and women and were negatively related to levels of education and income. Of the completely edentulous individuals, 89.9% had maxillary and mandibular complete dentures. Most of these dentures (83.2%) were worn during the day. More than one third of the respondents reported wearing one or both of their dentures while sleeping at night. For 77 of the completely edentulous individuals, examination revealed denture irritations, most of which were on the hard palate.

Mandible bone resorption as determined from panoramic radiographs in edentulous male individuals ages 25-80 years

Routine panoramic radiographs of 173 healthy edentulous males, aged 25-80 years, were measured for estimated bone loss using the Wical and Swoope (1974) technique. Results using this simple technique were comparable to other studies using more sophisticated methods but did not require exposure to additional radiation. Mean ratios of height of mandible (indicative of mandibular bone loss) decreased both with age of subject and with time after extraction. Efforts should be made to determine the usefulness of such archival radiographic films for a variety of studies.

Effect of maxillary edentulousness on mandibular residual ridges

Bone mineral density (BMD) was measured in five different regions of the mandible of 77 postmenopausal women. These women were also classified according to the remaining, clinically determined alveolar height in the edentulous distal regions of the mandible. The duration of edentulousness in the maxilla and in the mandible was determined anamnestically. All subjects were edentulous in the maxilla, and 42 were also edentulous in the mandible. The other 35 women had teeth only in region d35-d45. This study shows that after extraction of the last teeth in the mandible, the BMD of the cortical bone is not lowered, but that the BMD of the trabecular portion is lowered more by mechanical stress caused by the remaining natural teeth than by maxillary dentures. This feature becomes apparent when duration of edentulousness in the maxilla is compared with the BMD values of different regions in the mandible.

Effect of bone mineral density in skeleton and mandible on extraction of teeth and clinical alveolar height

Residual ridge resorption of the maxillae and mandible after tooth extraction adversely affects many edentulous people. The jaws of 355 postmenopausal women were examined clinically, and the number of teeth and the clinical height of alveolar ridges in edentulous jaws were determined. Each subject was asked when the last teeth had been extracted. To study the bone mineral status of each woman, the bone mineral densities of the femoral neck and the lumbar spine were measured by dual-energy x-ray absorptiometry. For 77 edentulous or almost edentulous women, the bone mineral density of the mandibular cortex and the spongiosa were measured by quantitative computed tomography. The results were studied to determine whether the general status of osteoporosis or the local bone mineral densities in the mandible affect the time of extraction of teeth or the remaining height of edentulous alveolar ridges. Neither the time when the teeth were lost nor the number of teeth was dependent on the general bone loss, but in some regions, the clinical height was affected.

Trabecular bone mineral density of mandible and alveolar height in postmenopausal women

Mineral density of the trabecular bone of the mandible was determined by single-energy QCT (quantitative computed tomography) for 74 totally or nearly edentulous menopausal women. These results were compared with the bone mineral densities (BMD) of their lumbar area (L2-L4) and femoral collum, measured by dual-energy x-ray transmission, Lunar DPX. The remaining height of the residual ridge at the symphysis of the mandible was measured on computed tomography (CT) lateral projection view, and an index of the residual ridge status was introduced. To determine whether general osteoporosis status affects the remaining height of the residual ridges, we compared these values with all results for bone mineral density. The BMD of the lumbar area and that of the femoral collum correlated well with each other, but the BMD of the trabecular bone of the mandible did not correlate with either of the other two BMD measurements. Measurements of residual ridge height did not correlate with any BMD values. The effect of possible bone loss earlier in life is no longer apparent in mandibular height or trabecular BMD over 20 yr after tooth extractions.

Study of the sagittal condylar path in edentulous patients

The inclination of the condylar path is a fundamental consideration in the prosthodontic treatment of the totally edentulous patient. The authors studied 55 patients at the University of the Basque Country, making three graphic registrations of the protrusive condylar movement on each side. Three examiners, working independently, used the tangential method to measure the angulation relative to Camper's plane. The results show that angulation varies greatly on each side and from one individual to another. In the treatment of edentulous patients, graphic registering techniques that can determine these variations should be used.

Bioelectric stimulation and residual ridge resorption

The use of exogenous pulsed electromagnetic fields (PEMF) to stimulate the healing of nonunions and other long bone defects is common in medicine. This investigation used the dog model and image analysis of standardized radiographs to assess loss of residual ridge height following extractions. It demonstrates the effectiveness of intermittent PEMF to reduce the rate of residual ridge resorption. It further suggests there may be a causal relationship between residual ridge resorption and the alteration of endogenous bioelectric signals caused by the loss of teeth.

Functional loading of the dentition during mastication

A method is described whereby the electrical activity in the masseter muscles is used as an index of chewing force. By using the kinesiograph, it was possible to determine the interrelationship of the phases of the chewing cycle and to measure the duration of each phase. On the basis of a pilot study of 10 dentate subjects and two complete denture wearers, it appears that, although the magnitude of the applied load is reduced in denture wearers, this is to some extent compensated for by an increase in the time it is applied. The results also suggest that a greater force is applied to the supporting mucoperiosteum when inverted cusp teeth are used in the construction of the dentures.

Tooth positions in the natural and complete artificial dentitions, with special reference to the incisor teeth: an interactive on-line computer analysis

A comparison of tooth positions and soft tissue profiles was made between samples of edentulous patients recently provided with new complete dentures, and dentate subjects. The dentures were marked with lead foil on the most prominent incisor teeth and labial surfaces of the flanges. Lateral skull radiographs were made with the jaws in centric relation. The dentate subjects were recorded with the teeth held in centric occlusion. Discrete soft and hard tissue landmarks were identified and recorded using an interactive on-line computer system, enabling linear and angular measurements to be made. A mathematical comparison was produced employing a series of independent t-tests. Composite computer tracings were also produced. Important differences were found between the two groups, in which the influence of the upper lip length, mandibular resorption, and selected overbite were identified as factors determining artificial tooth position.

Resorption of residual ridges (RRR) in rats

The post-extraction resorption of residual ridges (RRR) is a major and largely unsolved health problem, probably of multifactorial etiology. In order for one to study the role of specific factors in the pathophysiology of RRR, the use of animal models is desirable. The purpose of this study was to establish a reliable animal model and a standardized assay system to measure RRR for future experiments. A new oblique cephalometric device was designed to take pairs of xeroradiographs on the right and left sides of the rat skull and mandible at a 45-degree angle to the horizontal plane. Preliminary studies confirmed the reproducibility of the technique. All molars were extracted with minimal trauma from the right maxilla and mandible in five male Sprague-Dawley rats (40 days old). Longitudinal cephalographic examinations were performed before and immediately after extraction and at two, four, eight, and 12 weeks after extraction. Alveolar bone resorption was measured on enlarged cephalographs (5.7 X) at a point mesial to the mandibular first molar. Sequential mean bone resorption was 0.8 +/- 0.2 mm (S.D.), 1.0 +/- 0.3, 1.3 +/- 0.3, and 1.5 +/- 0.4, respectively. Graphically, these findings produced bone loss curves similar to those observed in man. These results indicate that the rat model may be utilized in longitudinal studies of the resorption of the residual ridge.

Autogenous dermal graft coverage of submerged roots in the dog

Dermal grafts were compared with conventional supraperiosteal recipient beds grafted with split-thickness skin for covering submerged vital roots in six dogs. Several potential advantages of this new technique are suggested.

Compressive strength of implanted porous replamineform hydroxyapatite

Porous replamineform hydroxyapatite is a nontoxic, nonallergenic synthetic ceramic currently under investigation as an implant for restoration of atrophic edentulous ridges. Previous studies have demonstrated its capacity to permit the ingrowth of bone into its pores. Evaluation of the material was carried out to determine its eventual compressive strength following implantation. Bony penetration results in a significant increase in strength, judged to be sufficient for support of dentures.

Spatial relationship between anatomic landmarks in edentulous patients: a radiographic study

In 67 edentulous patients the crests of the residual ridges, the incisive papillae, the maxillary tuberosities, and the mandibular retromolar pads were located and identified with metallic wires inside the acrylic resin denture bases. Occlusal cephalometric radiographs were used to record the spatial relationship between the described anatomic landmarks in the dentures with the mandible in centric relation.

A laboratory and clinical study of Trevalon denture base material

Trevalon is a denture base material which can be cured by three basic alternative curing cycles, thus providing a choice of processing technique which can be selected to suit laboratory or clinical needs. The flexibility of working properties is probably due to the interaction between on the one hand, the high molecular weight of the powder and on the other hand, the particle size distribution which are important factors influencing the doughing time (14 min), working time (40 min) and the exothermic reaction. The effect of each curing cycle upon the following properties of the material was investigated; dimensional accuracy, Young's modulus, modulus of rupture, impact resistance, water sorption, indentation resistance, creep and transverse bend behaviour. The particle size and molecular weight distribution of the powder were also evaluated. A clinical investigation of Trevalon was carried out by constructing complete dentures for a sample of patients, divided into three groups, each group having dentures processed by one of the three alternative curing cycles. Although some laboratory tests demonstrated that there were statistically significant differences between specimen bases, no clinical differences were recorded between dentures 1 year after construction.

Submucosal root retention. A two-year clinical observation

Eight subjects had the crowns of 21 teeth surgically amputated, and the roots were covered by alveolar mucosa. At the time of surgery, 17 teeth were vital and four had received endodontic therapy. After an average 2-year-period, 12 teeth (57%) remained submerged without complications. Two roots have been extracted, three have been successfully converted to regular overdenture abutments, and the remaining four have appeared in the mouth and are still under observation. Caution is urged as to expectations of a long-term prosthetic benefit from this procedure.

Some advances in endosseous implants

A major advance in endosseous implantology hinges on the coating of titanium implants by porous biodegradable, bioreactive tricalcium phosphate ceramic. When implanted into alveolar bone by a careful technique, the ceramic is resorbed to be replaced by bone. As a result, the endosseous implant becomes ankylosed to the bone. This represents a stable implant/bone interface as opposed to the unstable connective tissue interface that encapsulates many other implant devices.

Pattern of age related bone loss in mandibles

A study was carried out to analyze the pattern of the age related bone loss in the mandibular cortex and to establish normal values and the observed range of morphometric variables on microradiograms of bone sections taken from a well defined site anterior to and below the mental foramen. Specimens were obtained from 100 Danish subjects with no known systemic bone disease or severe mandibular atrophy. Microradiograms of 100-micron-thin undemineralized vertical ground cross-sections were produced. An electric point-counting system was used for the determination of 1) percentage bone mass, 2) mean cortical width (MCW), and 3) the percentage of Haversian canals with resorption surfaces. The analysis showed that cortical porosity and the percentage of Haversian canals showing resorption are unrelated to sex and increased after the age of 50. MCW and absolute bone mass (MCW x % bone mass) are greater in males than in females and show a parallel age related decrease after the age of 50. Furthermore, the age related increase in cortical thinning and porosity is dependent on the individual as well as on age. Marked individual variation confined the use of these parameters to group analysis.

Complete dentures using the TMJ articulator

A method of recording mandibular movements in a stereographic recording and a method of registering these movements by molding the controls in an articulator are described. Mandibular registrations are made using impressions rather than stabilized trial denture bases. The TMJ articulator used in the technique complies with all of the requirements of an articulator for prosthodontic treatment as outlined by the Academy of Denture Prosthetics.

Bone loss of edentulous alveolar ridges

RRR is probably multifactorial process subject to a wide number of covariables. In any given patient, these convariables will be in a unique combination which will determine the rate of RRR for that patient at that time. If the variable change in any given patient, the rate of RRR may change. The dentist who wishes to help his edentulous patient should seek to be sensitive to all these variables, and to understand and treat that unique combination of factors which exists in that patient.

Residual alveolar ridge atrophy: classification and influence of facial morphology

A method for grading residual alveolar ridge atrophies of edentulous maxillae and mandible has been devised for men and women. Comparisons were made in women and in men between the degree of atrophy and the vertical facial morphology. The study suggests some relationship between the total facial height (TFH), the vertical facial type determined by the Frankfort horizontal mandibular plan (FMA), and the atrophy of the alveolar ridges, especially for the mandible. Certain practical applications of these findings were suggested.