Playing in the Mountains

Playing in the Mountains


Its all too important to have some free time and fresh air apart from work! I often like to get in a “skin” whether with friends or just with my dog, Nellie. This picture is lighted by Xgames and required no additional head lamps to ski down. The second picture is at the top of the bowl at Highlands. For those of you who like to make “laps” its a common site . . . for those of you who don’t . . . you should make it up at least once.

Expansion of Atrophic Posterior Mandibular Ridge: A Case Report

Article from The Journal of Implant & Advanced Clinical Dentistry (www.jiacd.com)
Vol.4, No. 4 – September 2012

By: Marcus J. Blue, DDS and Charles M. Cobb, DDS, PhD
Marcus J. Blue, DDS: Private Practice of Periodontics, Basalt, CO and Charles M. Cobb, DDS, PhD: Professor Emeritus, Department of Periodontics, School of Dentistry, University of Missouri-Kansas City, Kansas City, MI

ABSTRACT
Background: Reduced function due to edentulation is related to skeletal change such as residual ridge resorption and loss of cortical bone thickness. Even with adequate cortical plate thickness, the ridge itself may present inadequate buccal-lingual dimensions, thereby requiring lateral expansion to facilitate successful dental implant placement.

Methods: A single case report is presented that involves lateral expansion of an edentulous atrophic posterior mandibular alveolar ridge to facilitate dental implant placement. The surgery consisted of a detached bone segment technique, stabilized by bone screws, and the adjunctive use of a particulate bone graft covered by a resorbable barrier membrane. Primary wound closure was achieved, healing was uneventful, patient morbidity was minimal, and a dental implant was successfully positioned and restored.

Results: The initial 3 mm atrophic ridge was expanded to 10 mm following the surgery that utilized a detached bone segment graft stabilized with bone screws and an adjunctive particulate bone graft. A 4.8 x 10mm bone level implant was successfully placed following 4 months of post-graft healing. The implant site appeared well vascularized and exhibited Type II bone density.

Conclusions: This single case report demonstrates that the detached bone segment technique can achieve substantial gains in horizontal ridge width of the edentulous posterior mandible. The increase in lateral dimension and maintenance of viable cortical bone allowed successful positioning of a large diameter dental implant.

INTRODUCTION

Reduced function due to long-standing edentulation is known to induced skeletal change such as residual ridge resorption and loss of cortical bone thickness.1 Even with adequate cortical plate thickness, the ridge itself may present inadequate buccal-lingual dimensions; a scenario commonly encountered in the edentulous anterior mandible and less so in mandibular molar regions. The placement of dental implants in an alveolus with inadequate horizontal dimensions is likely to compromise long-term stability and prognosis. Consequently, a variety of surgical approaches have evolved to increase the horizontal dimension of the deficient mandibular alveolus,2,3 including, among other procedures, guided bone regeneration,4,5 autogenic, allogenic, and xenogenic block grafts,6-10 distraction osteogenesis, 11,12 and ridge-splitting techniques.13-17

Based on the work of Miyamoto et al.,18 it appears that cortical bone thickness is important to initial implant stability, more so than implant length. Assuming this observation to be true then the dimensions of available cortical bone should be considered when selecting the preferred implant site.19 In cases of severe alveolar resorption, the posterior mandible is considered a difficult region for reconstruction with the ultimate goal of implant placement.20 Localized bone defects in the posterior mandible are frequently reconstructed with autogenous mono-cortical bone blocks prior to the placement of dental implants.6-8 In the current case, the authors present a single case report detailing the technique first presented by Basa et al.20 in which the posterior mandibular buccal plate is completely detached, moved laterally to increase horizontal alveolar ridge dimensions, and stabilized until appropriate healing occurred to allow insertion of a dental implant. The characteristic biomechanics of cortical bone and how such features can dictate the choice of surgical technique for the posterior mandible are discussed.

METHODS

Patient Presentation

Figure 1: Pre-treatment radiograph showing loss of molars, except #14 and #30, and slightly concave alveolar in area of #18 and #19.

The patient, a 44 year old male, presented to the University of Missouri-Kansas City (UMKC) undergraduate dental clinic with a chief complaint of a toothache associated with the mandibular left first molar (#19) of 2-weeks duration. A diagnosis of chronic irreversible pulpitis was determined. The patient’s medical history was essentially negative, i.e., no allergies, no use of tobacco, and no current medical conditions. Past medical history included a back surgery and removal of a colon polyp. The patient was classified as ASA 1.

Tooth #19 was treated by endodontic therapy. In the process of preparing the tooth for an endodontic post and crown build-up the mesial root developed a longitudinal fracture leading to difficult extraction with loss of buccal bone. The patient was subsequently seen 18 months later in the UMKC Graduate Periodontics Department for evaluation of a dental implant to replace tooth #19.

Figure 2: Facial view of the #18-#19 area showing concave profile of alveolus.

The periodontal examination noted slight plaque induced gingivitis, 12/132 sites exhibited bleeding on probing (9%), and there were no probing depths greater than 3 mm. At presentation the patient was missing all molar teeth except for #14 and #30 (Fig. 1). Occlusal analysis revealed bilateral group function with obvious occlusal wear on all remaining teeth. The patient admitted to a clenching habit. Evaluation of the #19 area edentulous ridge revealed an atrophic ridge with a Seibert class III contour (Figs. 2 & 3). A CBCT showed the ridge measured 3 mm in the horizontal dimension and featured a severe slant to the buccal of approximately 25-30 degrees, indicating loss of the buccal cortical plate during the extraction. In addition, the CBCT revealed that the crestal buccal and lingual cortical plates were fused with no intervening cancellous bone to a depth approaching 4 mm. The patient was informed that to achieve implant placement a horizontal ridge expansion would be necessary.

 

TREATMENT

Figure 3: Occlusal view of the #18-#19 area showing narrow buccal-lingual dimension.

Local anesthesia was achieved by using 2.5 carpules of Septocaine® (articaine HCl 4%, 40 mg/mL) with 1:100,000 epinephrine. The anesthetic was delivered by inferior alveolar field block and lingual infiltration to anesthetize any aberrant branches extending from the superior root o the ansa cervicalis.

 

Following anesthesia, buccal and lingual intrasulcular incisions were made, starting at the distal of tooth #22 which joined at the distal of tooth #20 to become a single crestal incision extending distally up the anterior border of the mandibular ramus. This incision design allowed for a relaxed full-thickness mucoperiosteal flap reflection and exposure of the underlying bony ridge, confirming the Seibert Class III defect, the horizontal dimension of approximately 3 mm, and the buccal slant. Given the ridge dimension and architecture a horizontal expansion of the ridge was undertaken using a combination of in situ autogenous bone block supplemented with a graft of allogenic bone particles, all covered by a barrier membrane.

The initial step was to place two pilot-hole indentations in the buccal cortical bone for future positioning of titanium bone screws (Fig. 4). The pilot-holes were centrally placed, approximately 8 mm apart, within an area measuring 10 mm x 20 mm, representing the size of the intended in situ block of bone. The next step utilized a NSK VarioSurg ® piezo-electric unit (NSK America Corp., Schaumburg, IL) fitted with a SG1 titanium nitride coated 0.5 mm blade and copious amounts of sterile water to place a 20 mm cut along the crestal ridge. Vertical cuts of 10 mm length were placed, one from each end of the initial crestal incision, and extending downward to the buccal. The final cut was then made with a SG2R blade, connecting the two vertical incisions (Fig. 5). All bony cuts passed through the cortical plate thereby allowing for eventual free separation of the bone block. At this point, the pilot-holes were extended through the buccal cortical place using a #4 carbide round surgical length bur. Immediately prior to freeing the bone block, shallow indentations were made in the buccal surface of the lingual cortical plate with a #4 carbide round bur to allow insertion of fixation screws in their proper position. OsteoMed™ (OsteoMed, Addison, TX) Auto-Drive® self-drilling screws (2 mm diameter x 14 mm length) were then placed in the bone block and gently screwed to place until they engaged the lingual cortical plate (Fig. 6). This action, aided with osteotomes, effectively lifted the bone block from the underlying cancellous bone while insuring proper positioning and stabilization and allowing lateral expansion of the atrophic ridge. Following fixation of the bone, a 5-6 mm gap remained between the in situ bone block and the lingual cortical plate (Fig. 7). Sharp edges and corners of the in situ block were smoothed and rounded slightly to insure a lack of irritation during healing.

Figure 4: Placement of pilot-hole indentations in the buccal cortical bone for future positioning of bone screws.

Figure 5: Outline of cuts made through the buccal cortical plate using a piezo-electric surgical unit.

Figure 6: Placement of bone screws to engage the lingual cortical plate and begin process of lifting the in situ autogenous block.

Figure 7: Stabilization of the in situ autogenous block.

The next step consisted of compacting Puros Allograft® (Zimmer Dental, Carlsbad, CA), hydrated in sterile water, within the space beneath the stabilized bone and included covering the entire in situ bone block and ridge (Fig. 8). The grafted area was then covered with Puros Copios® pericardium membrane (Zimmer Dental, Carlsbad, CA). The membrane was tucked under both the lingual and buccal mucoperiosteal flaps (Fig. 9). The buccal flap was released slightly by two periosteal releasing incisions without vertical components to insure blood supply.

Figure 8: Placement of particular bone graft material in the space crated under the in situ autogenous bone block, within the cut margin spaces, and over the bone block.

Figure 9: Covering of the grafted sites with pericardial membrane.


Figure 10: Primary closure of the surgical area using an interlocking continuous suture technique.

Figure 11: Facial view following exposure of graft site at 4 months post-surgery showing extent of bone regeneration.

 

Figure 12: Occlusal view of graft site at 4 months post-surgery showing a buccal-lingual ridge width of approximately 12 mm.

Primary closure was obtained and stabilized with Vicryl™ 4-0 suture (Ethicon, Inc., Somerville, NJ) using a continuous interlocking technique (Fig. 10).

The patient was placed on amoxicillin 500 mg, t.i.d., for 10 days and instructed to use an alcohol-free chlorhexidine oral rinse twice a day for three weeks. Sutures were removed at 2-weeks post-surgery.

POST-TREATMENT RESULT

Figure 13: Occlusal view showing wound closure following placement of a bone-level implant and healing abutment.

Following a 4-month healing period, the site was re-entered and measurements taken prior to implant placement. The initial measurement of a 3 mm atrophic ridge was expanded to 10 mm following the surgery (Figs. 11-12). The titanium bone screws were removed and osteotomy prepared and a 4.8 x 10 mm Straumann® bone level implant (Straumann USA, LLC, Andover, MA) was positioned and a healing abutment placed (Fig. 13). During placement of the implant the bone appeared to be well vascularized and to exhibit a Type II bone density. At 4 months post-implant insertion the quality of healing was considered to be excellent (Fig. 14). The final restoration of the implant was achieved at 4 months post-insertion and the patient was evaluated at 1 month and then 3 and 6 months post-restoration (Figs. 15 & 16). Following restoration of the implant the patient was fitted with a mouth guard to counter the biomechanical stresses from the clenching habit.

DISCUSSION

Figure 14: Mirror image view of quality of healing at 4 months post-implant placement.

The literature is replete with reports of effective bone augmentation using a variety of techniques. 3,14 Regardless of anatomical location or surgical approach, successful bone augmentation requires atraumatic manipulation of host bone, stabilization of grafted sites, preservation of adequate blood supply, space maintenance allowing ingrowth of osteogenic cells, prevention of connective tissue invasion that would encapsulate interpositional bone grafts, and avoiding tension on soft tissues when achieving primary wound closure.2,13,14,17,22 In cases involving expansion of atrophic alveolar ridges, stability of dental implants is primarily dependent on cortical bone.18,19,23

Figure 15: Final radiograph with restoration at 10 months post-implant placement.

The alveolar process of the posterior mandible, assuming the presence of teeth, typically exhibits a well developed buccal and lingual cortical plate comprised of a relatively thin outer layer of lamellar bone and a thickened subjacent layer of Haversian bone that transitions into cancellous bone. Various reports have estimated the thickness of cortical bone in the dentate mandibular 1st molar area to range from 0.6 mm to 2 mm near the crest 24-27 or 0.8 mm to 3.4 mm measured at 9 mm apical of the CEJ.25 However, with extraction of teeth the histologic and macroscopic anatomy of the alveolar ridge undergoes dramatic change.

Figure 16: Facial view of final restoration at 10 months post-implant placement.

It has been determined that cortical bone from all regions of the facial skeleton of edentulous individuals is thinner than in dentate skulls.1 Thus, depending on individual variation in bone turn-over and duration of edentulism, the cortical plates of the posterior mandible may or may not be of sufficient thickness to offer adequate support to implant placement. In the present case, several issues were considered that ultimately determined the surgical approach. First, although the time from extraction to the initial evaluation for implant placement was only 15 months, there was significant resorption mandibular posterior alveolus. Second, expansion of the alveolus by a simple ridge splitting osteotomy was contraindicated due to the horizontal crestal width of 3 mm and, as noted on the CBCT, fusion of the crestal buccal and lingual cortical plates with no intervening cancellous bone to a depth of 4 mm. Third, the lack of elasticity associated with cortical bone in the posterior mandible would require either an apical hinge cut or a more aggressive osteotomy through the entire thickness of the cortex, thereby allowing lateral repositioning and avoidance of an adverse fracture.15,28-30

Cortical bone exhibits a higher modulus of elasticity than cancellous bone, is stronger and more resistant to deformation, and will bear more load in clinical situations than cancellous bone.31 Indeed, it has been demonstrated that the edentulous mandible exhibits greater inelasticity than the dentate mandible in the retromolar region.32 As Bravi et al.33 noted, the inelasticity of mandibular cortical bone generally dictates a two-stage delivery of dental implants. Thus, it is not surprising that the absolute amount of cortical bone has more influence on implant stability than does cancellous bone. Based on the work of Baumgaertel and Hans,24 thickness of the buccal cortical bone in area of implant placement in the present case was estimated to range from 1.83 to 2.49 mm – a thickness that certainly would not allow horizontal repositioning of the buccal plate without an apical osteotomy. Furthermore, as Flanagan26 based on clinical experience, the mandibular lingual cortex is generally thicker than the buccal cortex. This observation appears to be supported by the fact that clinicians often utilize the lingual cortex for bracing osteotomes without inducing fractures. Thus, the lingual cortical plate can be used to anchor bone screws for stabilization of a detached bone segment.20

The rate of ridge atrophy in this case was relatively rapid and severe. The rate of atrophy is highly unpredictable as it can vary greatly between patients and even within the same person at different times or in different regions within the jaw.34 Alveolar atrophy is greatest during the first year post-extraction and without functional stimulation35 can become a life-long process.34 Given these observations, the rate of alveolar atrophy in the present case appears to be within normal boundaries.

It has been suggested that success of implants placed in pristine bone should be validated after 5 years of function.36 One could argue that a similar standard be used for validation of implants placed in sites following a lateral expansion procedure. In this regard, it should be noted that the most common complication during a lateral ridge expansion surgery is fracture of the buccal cortical plate.3 In the current case this possibility was avoided by using the detached bone segment approach.

Other reported complications observed during ridge expansion include loosening or fracture of bone screws, prolonged morbidity, paraesthesia, and membrane exposure with resulting loss of graft.3 Interestingly, lack of osseointegration has been reported in a relatively small number of cases.3 None of the reported complications was encountered in the current case. Thus, after six months of implant function the long-term success of the current case would appear favorable.

CONCLUSION

This single case report demonstrates that the detached bone segment technique first reported by Basa et al.20 can achieve substantial gains in horizontal ridge width of the edentulous posterior mandible without the morbidity associated with a secondary donor surgical site. The increase in lateral dimension and maintenance of viable cortical bone allowed successful positioning of a large diameter dental implant

Does Tooth Loss Influence Sleep Apnea?

By Rabia Mughal, Contributing Editor
April 5, 2012 — Previous studies have speculated that there may be an association between edentulism and worsening obstructive sleep apnea (OSA), but research presented at the recent American Association for Dental Research annual meeting did not find a link.

“We came across some papers stating that individuals who slept in their complete dentures had an improvement in their OSA,” study author Jeff Tanner, DDS, an oral and maxillofacial surgery resident at the University of California Los Angeles (UCLA), told DrBicuspid.com. “Their assumption was that tooth loss/edentulism contributes at least in part to the worsening of OSA.”

When people become edentulous, several physiological changes take place, Dr. Tanner noted. For example, the vertical dimension of occlusion reduces, the tongue grows larger because of the space that is no longer occupied by teeth, the position of the tongue changes, and the tongue rests in a different position.

Since no prior study has ever examined whether or not tooth loss per se was a predictor of OSA, the researchers decided to investigate this connection.

“When we became interested in this topic we found that there were several publications that had dealt with this issue, but not so directly,” he said during the session.

VA health system data

Dr. Tanner and his colleagues hypothesized that people with fewer teeth — especially those who are edentulous — have more serious OSA after controlling for age and body mass index (BMI), which are known predictors of OSA.

“This connection would be huge.”
— Jeff Tanner, DDS

They conducted a retrospective chart review of patients from the greater Los Angeles U.S. Department of Veterans Affairs (VA) health system who were referred to the dental service for treatment of OSA. The researchers looked at the electronic medical records of 210 male veterans who had already undergone a sleep study at the VA hospital and were able to collect the age and BMI of these patients. The researches also used an apnea-hypopnea index to classify the severity of the patients’ OSA.

They then used panoramic radiographs to quantify teeth using three different methods: total teeth lost, mandibular teeth lost, and posterior dental functional units lost.

Here are the key results:

  • Of the 210 subjects, 25.5% had not lost any teeth, 36.6% lost one to five teeth, 20.8% lost six to 16 teeth, and 17.1% lost more than 16 teeth.
  • 30% of the individuals had mild OSA, 36% moderate OSA, and 34% severe OSA.
  • The bivariate association between the number of dentition present and severity of OSA showed no significance.
  • In multivariate analysis, age and BMI were significant predictors of OSA severity, while total teeth loss was not significant

“The degree of tooth loss is not associated with OSA severity,” the authors concluded. “Tooth loss does not worsen OSA. ”

More research needed

OSA is difficult to understand because of the causative factors, Dr. Tanner toldDrBicuspid.com.

Age and obesity are proven predictors so the study controlled for those variables; however, the authors were still not able to prove that tooth loss predicted a worsening of OSA, he noted.

This line of research could be improved by obtaining a sleep study on the same individual prior to edentulism, after edentulism, and wearing complete dentures, Dr. Tanner added.

“Only by conducting this type of study will we be able to be certain to state whether or not tooth loss predicts OSA,” he said. “If in the future it could be stated that edentulism worsens OSA, it would be a strong case for dentists to attempt to restore patients back to a dentate state with implants which maintain alveolar ridge height unlike dentures.”

Given that OSA is an epidemic that is just now catching the public’s attention, “This connection would be huge, as that type of treatment would be medically driven dentistry, possibly covered by medical insurance,” he concluded.

 

Dr. Jeffrey Tanner

Bacteria From Mouth Can Lead to Heart Inflammation: Study

Once in the bloodstream, it can evade the immune system
MONDAY, March 26 (HealthDay News) — A type of bacteria from the mouth can cause blood clots and lead to serious heart problems if it enters the bloodstream, a new study indicates.

The bacteria, called Streptococcus gordonii, contributes to plaque that forms on the surface of teeth. If the bacteria enters the bloodstream through bleeding gums, it can cause problems by masquerading as human proteins, the researchers found.

The study authors, from the Royal College of Surgeons in Ireland and the University of Bristol in the United Kingdom, discovered that S. gordonii can produce a molecule on its surface that enables it to mimic the human protein fibrinogen, which is a blood-clotting factor.

This activates platelets (cells that are found in blood and involved in clotting) and causes them to clump inside blood vessels. The resulting blood clots encase the bacteria, protecting the invader from the immune system and from antibiotics used to treat infection.

Platelet clumping can result in growths on the heart valves (endocarditis) or blood vessel inflammation that can block blood supply to the heart or brain.

The findings, to be presented at a Society for General Microbiology meeting in Dublin this week, could help lead to new treatments for infective endocarditis, said study author Dr. Helen Petersen.

“In the development of infective endocarditis, a crucial step is the bacteria sticking to the heart valve and then activating platelets to form a clot,” Petersen said in a society news release. “We are now looking at the mechanism behind this sequence of events in the hope that we can develop new drugs which are needed to prevent blood clots and also infective endocarditis.”

The researchers stressed that it’s important to keep the gumshealthy and get regular dental care.

“We are also trying to determine how widespread this phenomenon is by studying other bacteria related to S. gordonii,” Petersen said. “What our work clearly shows is how important it is to keep your mouth healthy through regular brushing and flossing, to keep these bacteria in check.”

The U.S. National Heart, Lung, and Blood Institute has more about endocarditis.

http://health.usnews.com/health-news/news/articles/2012/03/26/bacteria-from-mouth-can-lead-to-heart-inflammation-study