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JADA Specialty Scan - Prosthodontics
Prosthodontics - A Quarterly Newsletter on Dental SpecialtiesJADA Specialty Scan

Minimum abutment height and bone loss

Shorter abutment height leads to greater marginal bone loss in cement-retained prostheses, and platform-switched implants maximize abutment height benefits better than nonplatform-switched implants in limiting marginal bone loss, according to a study published in the March/April issue of The International Journal of Oral & Maxillofacial Implants.

“The platform-switching concept seeks to eliminate oral microflora and consequent inflammatory response from crestal bone in order to limit bone resorption and thus re-establish biologic width,” researchers wrote. “The present study confirms that the platform-switching concept can minimize marginal bone loss over a 1-year period, in agreement with a previous trial and recent meta-analysis.”

The retrospective study’s aim was to verify the minimum prosthetic abutment height to minimize bone loss after wide-diameter implants were placed in maxillary bone and to determine if this marginal bone loss could be associated with grafting using a transcrestal technique, particularly because this technique uses the same surgical bed for sinus elevation as that created to place the implant.

Italian and Spanish researchers, including dentists in private practice and dental school professors, conducted the study. Two of the dentists examined and treated, in their private offices, patients requiring placement of a single delayed posterior implant adjacent to natural teeth in the presence of at least 6 mm of ridge width below the maxillary sinus floor and in the presence of occlusal contacts with the opposing dentition.

Patients (28 women and 28 men; age range, 25-75 years, mean, 47.6 years) met the inclusion criteria, which called for good general health, nonsmokers, absence of diseases affecting bone metabolism and wound healing, absence of uncontrolled periodontitis, no specific disease of the maxillary sinus, and no regular medication consumption for at least 3 months before treatment. They also received oral hygiene instructions and nonsurgical periodontal therapy before implant placement. Researchers checked crestal bone height and sinus health preoperatively by means of cone-beam computed tomography.

Two groups of patients, a control group and a test group, received 2 different implant types with similar neck design. The test group received platform-switched implants, and the control group received nonplatform-switched implants. Patients requiring bone augmentation received unilateral sinus augmentation using a transcrestal technique with mineralized xenograft.

The results showed that 25 control group patients exhibited average mesial (0.78 mm) and distal (0.90 mm) marginal bone loss that was more than twice that of the 26 test group patients (0.30 mm mesially and 0.38 mm distally), while their average abutment height was similar. Researchers found no statistically significant differences regarding marginal bone loss of implants placed in native maxillary bone compared with those placed in grafted areas.

Read the original article here.


Consulting Editor: Donald A. Curtis, DMD, FACP
Diplomate, American Board of Prosthodontics
Professor, University of California San Francisco

Patient satisfaction and implant-supported overdentures

In an investigation of patient satisfaction related to clinical denture quality and interimplant distance (IID) in mandibular overdentures supported by 2 unsplintered implants, researchers found that denture stability had the most influence on patient satisfaction and that IID had no effect on either satisfaction or clinical quality. The International Journal of Prosthodontics published the study in its November/December 2017 issue.

The international team included researchers from Saudi Arabia, Canada, and the United States. They stated that in vitro studies evaluating effects of dental implant distribution on vertical and oblique dislodging forces on overdentures and other confounding factors affecting stability and retention of overdentures had inconsistent conclusions.

“Moreover, evidence on patient-mediated concerns, namely quality of life and satisfaction as related to inter-implant distance (IID) is scarce,” researchers wrote.

Their study population of interest was completely edentulous patients rehabilitated with implant-retained overdentures with 2 Locator attachments from September 2011 through May 2016. Independent investigators, who were not involved in treatment, randomly selected 40 edentulous patients for the study. Researchers established inclusion criteria to require that patients were wearing their dentures and were able to communicate clearly with the clinician. They excluded patients with the presence of general physical or psychological disorders that precluded normal oral function, comprehensive clinical examination, or the completion of the questionnaires.

Denture fabricators were not aware of the study objectives nor were they involved in the denture quality evaluation process. A Denture Quality Evaluation Form assessed the dentures objectively on the basis of the following criteria: esthetics (lip support, lower lip line), retention and stability of both maxillary and mandibular dentures, and balanced articulation. However, based on the study’s objectives, researchers ultimately eliminated the esthetics items.

To evaluate patient satisfaction, researchers collected patient-mediated outcomes data using an Arabic version of the validated self-report Denture Satisfaction Scale. Variables assessed on the scale included overall satisfaction, retention, stability, comfort, esthetics of maxillary and mandibular dentures, chewing efficiency, and ability to speak.

To measure IID, clinicians made irreversible hydrocolloid impressions of the mandible and poured in die stone. They adapted orthodontic wire to the mandibular alveolar ridge crest extending from the center of 1 implant to the center of the other and measured IID in millimeters.

For statistical analysis, researchers used Spearman correlation analyses to identify possible correlations, with significance level set at P < .05.

The study discussion includes details of findings for each null hypothesis, declared as: null hypothesis 1, patient satisfaction is not related to the clinical quality of the dentures; null hypothesis 2, IID has no effect on the clinical quality of the dentures as evaluated by the clinicians; and null hypothesis 3, IID does not influence patient satisfaction with their dentures.

The main result researchers cited was that clinicians’ overall mean (standard deviation) rating of the clinical quality of the dentures was 91.50% (6.27%). Results also revealed that stability of the mandibular overdenture and of the maxillary conventional complete denture had significant relationship to satisfaction (r = 0.389 and r = 0.44, respectively), and IID had no effect on the quality of either denture in terms of retention, stability, or occlusion.

Read the original article here.


Low Dose, High Quality
Planmeca Ultra-Low Dose protocol enables 3D imaging with a lower patient radiation dose – achieving an average of 77% reduction in radiation dose, when compared with standard imaging protocols – without statistical reduction in image quality*.

*According to “Dosimetry of Orthodontic Diagnostic FOVs Using Low Dose CBCT Protocol” by JB Ludlow and J Koivisto. For a copy of this study visit:


Moderately controlled diabetes, implant survival and bone loss

The results of an Israeli study investigating long-term implant survival rates and bone loss in patients with moderately severe type 2 diabetes mellitus showed survival outcomes comparable with those of the nondiabetic population. The International Journal of Oral & Maxillofacial Implants published results in its March/April issue.

Researchers from the Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University in Tel Aviv, Israel, designed a retrospective observational study based on medical records from a general practitioner’s dental office.

“Dental implants are a successful and predictable treatment for replacing missing teeth, though implant success is dependent upon an effective osseointegration process while healing takes place,” the study’s researchers wrote. “The presence of type II diabetes may disrupt this process, leading to impaired bone healing. … ” They also stated that vascular alterations related to type 2 diabetes can impair blood circulation around dental implants and that type 2 diabetes increases risk of developing an infection due to reduced chemotactic and phagocytic function of neutrophils.

The researchers acknowledged and discussed a number of other studies that have assessed clinical implant survival outcomes of dental implants in people with diabetes but declared that information on long-term bone loss in patients with type 2 diabetes is sparse.

Their hypothesis was that they expected that long-term implant survival rates and the extent of bone loss in patients with moderately controlled type 2 diabetes to be similar to the rates reported in the nondiabetic group, as has been reported in a previous study conducted in the same patient population.

Inclusion criteria covered partially edentulous patients subsequently treated with implant-supported prosthetic restoration who were at least 18 years old with demonstrated ability to maintain oral hygiene. Significantly, researchers reviewed records of patients who had moderately controlled type 2 diabetes with glycated hemoglobin up to 8% and glucose level below 150 milligrams per deciliter.

Researchers excluded patients with periodontal neglect; patients who did not report for annual follow-up visits; external hexagonal and machine-surfaced implants; and patient records with incomplete surgical or restorative data or nondiagnostic radiographs.

Researchers reviewed 3,256 medical records and identified 169 patients with 1,112 implants who met inclusion criteria. Over the retrospective period of 20 years of follow-up research, 6 dentists used 3 different implant placement methods: implants immediately placed after tooth extraction, implants placed 6 to 8 weeks after tooth extraction to allow for primary healing, and implants placed 4 to 6 months after tooth extraction.

More than 90% of the 5 types of restorations were for a full arch, and 9% of the patients were smokers. The mean follow-up time was 8.7 years with a minimum of 4.9 years.

Researchers determined an overall survival rate of 94% after 67 implants failed. Overall mean (standard deviation) bone loss was 1.98 (1.81) mm. Data were comparable to those published earlier with no statistical significance appreciated in survival rate between the diabetic population and the nondiabetic population. Also, researchers said, “The delayed insertion protocol presented less bone loss compared with other insertion methods.”

Read the original article here.

Planmeca Calm

The No. 1 disruptor of image quality for dentists is patient movement. During a dentist appointment, a doctor may need to take several 3D x-ray scans to get a single image of diagnostic quality. Oftentimes a child, individual with special needs, or an elderly patient is challenged to remain still.

Planmeca CALM (Correction Algorithm for Latent Movement) is a proprietary algorithm that addresses a doctor’s concerns over patient movement during a 3D scan. With Planmeca CALM, Planmeca cone beam computed tomography can analyze and compensate for the slight movement that can occur during a scan to provide improved diagnostic quality images. The addition of this feature (available for Planmeca ProMax 3D systems; check system requirements with your Planmeca representative) streamlines the imaging process, minimizing retakes while improving diagnosis. The important benefit to patients—less retakes equals less radiation while achieving better diagnostic images.

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ACP’s fall calendar includes 2-day CE course in Seattle, annual session in Baltimore

All dental professionals are invited to attend the ACP Prosthodontic Review Course, Sept. 7-8 in Seattle. This two-day course is ideal for anyone who is new in practice, interested in becoming board certified, or would like to stay up to date on the latest trends in prosthodontics. Speakers will discuss both traditional and innovative methods and materials for fixed, removable, and implant prosthodontics. Register at or call 312-573-1260.

The 48th Annual Session of the American College of Prosthodontists will take place in Baltimore, Oct. 31-Nov. 3. Led by Dr. Radi Masri, program chair, and Dr. Robert Taft, ACP president, speakers will explore the leading edge of pre-prosthetic surgery and implant site development, advances in dental ceramics, and how to integrate the latest technologies into prosthodontic workflows. Speakers, topics, and registration are online at


Planmeca extraoral bitewings
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JADA+ Specialty Scans and JADA+ Scans

JADA+ Specialty Scans and JADA+ Scans are quarterly newsletters updating dentists on the latest research in selected specialties and disciplines in dentistry. ADA Publishing and the consulting editors from the represented specialties and disciplines aggregate and summarize research from previously published materials, each item attributed to its publication of origin. JADA+ Scan specialties and disciplines include endodontics, oral pathology, orthodontics, pediatric dentistry, periodontics, prosthodontics, radiology, cosmetic/esthetic and osseointegration. The ADA has engaged the specialty organizations in these areas as well as its own Science Institute and Division of Legal Affairs to assist with these newsletters. View past issues here.

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