Q: What is laughing gas?
A: It is a combination of nitrous oxide and oxygen we offer our patients during dental procedures. As an inhaled form of sedation, it is extremely helpful with children and adults who are fearful or anxious.
We, dentists test products or equipments on us to learn the effects before we use them for the patients:)
Ok, let’s see the laughing gas test on dental students:)
Sinus floor augmentation Elevation and augmentation of the sinus floor is a widely accepted method of treatment. The application of Bio-Oss® alone or in combination with autogenous bone is very well documented scientifically. Various factors influence the decision whether autogenous bone should be mixed with Bio-Oss®. The use of Bio-Oss® alone is recommended when there is adequate residual bone height (< 5 mm) and good quality of the surronding bone. With less than 5 mm of residual alveolar bone, adding autogenous bone to Bio-Oss® is recommended. Clinical Case: Sinus Floor Elevation
Case by Dr. Stephen Wallace
Histologic documentation is important to assess the biological response to any regenerative therapy. The photomicrographs below document the lack of any immunologic response to Bio-Oss®; rather new bone formation is present on the surface of the Bio-Oss® and forms bridges between the particles. In approximately six months, Bio-Oss® becomes integrated with newly formed lamellar bone; it is subsequently included in the physiologic remodeling process.
Histology – Maxillary Sinus Floor GraftCase by Dr. Pascal Valentini, Histology by Dr. Robert Schenk; Berne, Switzerland 
At 6 months postgrafting, the grafted area (coronal half of the section) consists of a dense scaffold of Bio-Oss® (*) interconnected by new bone. The orignial host bone (apical half of the section) represents a spongiosa of lower density. (Original magnification x 3.2)
At 6 months postgrafting, remodeling activity in the newly formed bone is high. Bio-Oss® (*) particles exposed to bone marrow are often lined by clear seams (arrows) partially covered by osteoclasts (arrowheads). (Original magnification x25.) 
At 12 months postgrafting, the interconnecting bone in the grafted area has matured. The ongoing remodeling activity spreads out upon Bio-Oss® (*) surfaces that are exposed to bone marrow. (Original magnification x25.)
Bio-Oss® particle (*) enclosed by bone 12 months postgrafting. Particle surfaces exposed to marrow are lined by clear seams (arrows). Intensely stained lines indicate recalcification (arrowheads). (Original magnification x 50.)
At 12 months postgrafting, new bone formation is seen in a preformed canal in a Bio-Oss® particle (*). The clear seam (arrows) within the canal indicates additional osteoclastic activity and is continuous with a dark seam (arrowheads) formed underneath newly deposited, packed lamellar bone. (Original magnification x50). Bio-Oss® and Bio-Gide®: Long-term implant survival The slow resorption of Bio-Oss® results in a greater bone density and may have apositive influence on implant stability in the augmented maxillary sinus.2 
Overall survival rates at 6.5 years following maxillary sinus augmentation:1Bio-Oss® alone = 96.8%Bio-Oss® + DFDBA = 90% Patients treated with Bio-Oss® alone show comparable survival rates using1-stage or 2-stage procedures.1 
Comparable results with particulate autogenous bone or Bio-Oss®/Bio-Gide®.2 The resistance of Bio-Oss® to resorption is advantageous in maintaining the initial dimensions of the augmented graft. In a meta-analysis, implant survival rates in the maxillary sinus increased by covering the lateral window with a membrane.3*93.6% survival rate with membrane*88.7% survival without a membrane. *p < 0.05 The use of a membrane has a positive influence on vital bone formation and implant survival The efficacy of membrane placement over the lateral window has been reported as both an increase in vital bone formation and as a resultant increase in implant survival. Three controlled trials (Tarnow, Tawil, Froum) show higher implant survival when a membrane is utilized. Two of these trials also show increased bone formation of 60-100% with a membrane. A comparison study (Wallace) of non-absorbable (ePTFE) and absorbable (Bio-Gide®) membranes showed similar histomorphometric and implant survival rates. Histology – Graft with a Collagen Membrane
Histology by Dr. Stephen Wallace
Eight month lateral window core biopsy of 100% Bio-Oss® graft covered with Bio-Gide® membrane. Membrane resorbed with lateral wall (left) reformed in bone the graft (right) consists of equal parts newly formed bone (30%) and residual Bio-Oss® (30%). Original magnification x 10. Higher magnification of internal portion of biopsy reveals intimate contact and “bridging” between Bio-Oss® particles (yellow) and newly formed bone (red). Original magnifcation x 20 Histology – Graft with an ePTFE MembraneHistology
Eight month lateral window core biopsy of 100% Bio-Oss® graft covered with ePTFE membrane. The graft consists of equal parts newly formed bone (30%) and residual Bio-Oss® (30%). Original magnification x 10. Higher magnification reveals intimate contact and “bridging” between Bio-Oss® particles (yellow) and newly formed bone (red). Original magnifcation x 20 References: 1-Valentini P, Abensur DJ. Maxillary Sinus Grafting with Anorganic Bovine Bone: A Clinical Report of Long-Term Results. J Oral Maxillofac Surg 2003; 18 (4) 556-560. 2-Hallman M, Sennerby L, Lundgren S. A clinical and histologic evaluation of implant integration in the posterior maxilla after maxillary sinus floor augmentation with bovine hydroxyapatite and autogenous bone. J Oral Maxillofac Surg 2002; 60:277-284. 3-meta-analysis: Wallace S, Froum S; 2003
INTRODUCTION OF NORMAL AND PARA FUNCTIONS OF
TEMPORO MANDIBULAR SYSTEM
(3 “chews” per side, then a functional shift)
The image to the left is demonstrating normal reciprocal functioning of the Lateral Pterygoids and Masseters/Med.Pteygoids/Temporalis’.
The Lateral Pterygoids advance the condyles, thereby opening the mouth (depressing the mandible), with the assistance of the Digastric (next webpage).
The oblique orientation of the Masseters and Medial Pterygoids create a sling. The non-working side Medial Pterygoid contacts simultaneously with the opposide side working Masseter.
It is this oblique orientation of the Med.Pterygoids and Masseters that create the functional “shift” of the mandible, not an unilateral contraction of a Lateral Pterygoid.
In normal chewing function, the mandible opens, and then, while initiating closing, there is a shift slightly to the side of the bolus, due to the orientation of the masseter and medial pterygoid. There is no “canine rise” during normal chewing fuction. Canine rise is mechanism to combat parafunction.
The moving yellow dot in the jaw tracing to the left shows the tracking of the gingival margin of a lower incisor during the left “working” movement of chewing. The red lines are jaw movements with the teeth in contact (excursive grinding to each side). The outter most line is the envelop of maximum movements.
Notice how the during normal masticatory function, the teeth do not contact, but may occasionall glance off each other.
(From Lindeen and Gibbs: Advances in occlusion, Boston, 1982, John Wright PSG, p.19)
The animations above show the effect of the contractions of the lateral pterygoids: the advancement (translation) of the condyles. A voluntary opening of the mandible requires the LPs to contract, thus the immediate translation upon attempted opening.
However, a voluntary attempt at closing requires the immediate retrusion of the condyles by the posterior temporalis, thereby “un-translating” the condyles. At the final arc of closure, the condyle is braced against the eminance, while the anterior temporalis rotates the mandible closed.
The animation above and to upper demonstrate how the condyle immediately translates upon opening during masticatory function, due to the contraction of the lateral pterygoid. As closing ensues, the LPs relax, and the elevators contract. The tension of the posterior segment of the temporalis “un-translates” the condyle. During last portion of closing, the anterior temporalis and masseters brace the condyles against the eminance (seating to “CR”), referred to as “rotation”.
The blue dot is the position of the gingival margin of the central incisor. The condyle translates immediately upon opening, and is rotating during the final phase of closure. The superior head of the lateral pterygoid is bracing the disc against the eminance as the elevators rotate the mandible closed against the resistance of the bolus.
Just as the anterior temporalis can sustain considerable contaction intensities over extended periods, so it may be with the posterior temporalis. The result would not be the clenching of the teeth, but of the blockage of the airway. It is this possiblity that makes for the varying reports of tooth soreness from the use of anit-snoring/anti-apnea devices, that attempt to hold the jaw forward. The reason why there is difficulty in holding the jaw forward for some patients is their intensity of retrusion by the posterior temporalis.
Bruxism can not be casually described as “hyperactivity of the lateral pterygoid”. Each of the graphics below displays identical degreess of LP “hyperactivity”:
Only the graphic to the far left can be considered to NOT be bruxism, although there IS hyperactivity of the LPs. The definitive component of bruxism is the degree of parafunctional elevation, that is, the clenching component. An accurated definition of bruxism is: Jaw clenching, with or without forcible excursive movements, where the intensity of the clenching dictates the severity (or lack of) grinding (neither the graphic at the far left or the far right would display tooth wear, yet the graphic at the far right is the most extreme form of bruxism).
Above: “Protusive Clenching”
In the event the Temporalis’ do not cease their active contractions, scenarios of varying degrees of parafunction result, as the Lateral Pterygoids encounter resistance to their attempts at condylar advancement, thereby increasing their intensity of contraction and strain on their origins and insertions: the pterygoid plates of the sphenoid bone, and the condylar neck and disc.
The degree of frequency, duration and intensity of the contractions of a Lateral Pterygoid is a function of the resistance provided by the parafunction ipsilateral and/or contralateral Temporalis. For example, in the animation to the left, as a Lateral Pterygoid attempts to translate its condyle, it is met with resistance provided by the contralateral Temporalis, thereby causing the Lateral Pterygoid to pull its condyle in a medial direction toward the contralateral contact.
Dentistry has stipulated that an elevated mandible
is a presentation of a “functional” position.However,
the duration and frequency of elevation is rarely taken into consideration. Just as elevating one’s arm from its rest position to an elevated position with enough frequency and duration will present symptoms of parafucntion, the same applies to a mandible.
Once the mandible (or an arm) has been elevated, the resistance to the elevation will dictate the intensity of contaction and degree of symptoms. Whereas skeletal muscle needs a foreign resistance to contract with maximal intensity, the temporalis has built in resistance, the maxilla. Sleeps studies have recorded clenching intensities above voluntary maximum
James P. Boyd, DDS
Laser-powered HEMI
Planning a hemisection to manage untreatable roots is a minimally invasive option. Performing it with a laser makes it even more so.
According to Souviron and Groh,1 hemisection is a surgical procedure whereby the roots of a tooth are separated and treated as individual teeth; it is used when maintaining the intact tooth is impossible because of gum disease. Reese2 uses this procedure when only one root of a “key tooth” suffers a persistent endodontic failure. Parmar and Vashi3 indicate that tooth resection preserves as much of the tooth structure as possible rather than sacrificing the whole tooth. Bühler4 states that “clinicians should seriously consider hemisection as an alternative for every molar extraction.” Hemisection involves cutting the tooth in half and removing the root and the portion of clinical crown supported by that failing root.
Light vs. drill
The traditional method of treatment for hemisection involves use of the air-driven handpiece, which can create microscopic fractures in the remaining tooth structures and vibration-induced separation of the restoration from the tooth structure. In addition there is a possibility of air embolism at the surgical site. The Waterlase Er,Cr:YSGG laser (Biolase Technology, www.biolase.com) allows nontraumatic removal of the root using laser energy to section the root from the tooth. The laser also can be used to sterilize the surgical site and promote rapid healing.
Case 1 below experienced no vibration during the hemisection, rapid healing due to laser decontamination of the surgical site, decreased trauma to the surgical site, and no postoperative swelling. Case 2 experienced vibrations during surgery, some post-operative swelling and discomfort, and slower healing of the extraction site. A comparison of the two different approaches indicates that use of the laser results in faster healing with less trauma.
Case 1: Laser assisted
This first case report describes the use of the laser to hemisect a failing mandibular molar.
Treatment planning
A 60-year-old female patient presented with a sore tooth that showed a failure of a previous endodontic therapy. She had a complicated medical history and was taking medications for arthritis, asthma, and glaucoma. These medications included Theragran-M, vitamin E (400 IU), glucosamine chondroitin, Medroxypr (10 mg), and Arthricare. Her medical condition was controlled by these medications. There were no contraindications to dental treatment.
Fig. A is a radiograph showing failure of the endodontic therapy. Treatment options included extraction or retreatment, and the patient decided on retreatment of the involved tooth.
(A) View of patient’s previous failed endodontic therapy. Patient decided on retreatment of involved tooth.
Endodontic therapy was successfully completed with no difficulty. The patient had no complications following retreatment.
Fig. B shows the completed retreatment of all canals.
(B) View of complete endodontic retreatment of all canals.
The patient returned six months later complaining of soreness surrounding the same tooth. Examination revealed a fractured mesial root and abscess (Fig. C). The fractured root extended up to the crown, and the tissue over that root was swollen. Bone loss in the furcation had occurred decreasing the radicular bone height.
(C) Six months later, patient complained of soreness surrounding the same tooth. View of fractured mesial root. Patient opted for hemisection.
This change in the patient’s condition necessitated a new discussion of treatment options. Those options for treatment included extraction and placement of a fixed bridge; extraction and an implant followed by placement of a crown; extraction and a removable partial denture; and hemisection of only the involved root. According to Noguera and Russo,5 hemisection is a procedure that involves removing one-half of a tooth and restoring the remaining root as a single tooth. This patient chose the hemisection in order to remove the source of the abscess but keep the clinical crown of the tooth.
Procedure
Before the Waterlase laser was introduced, hemisection was a traumatic procedure that used a highspeed drill with vibration and forced air/water spray. The Waterlase laser uses hydrokinetic energy to “cut” through the tooth structure with no vibration and only a water mist that is not projected under pressure. Fig. D is a photo showing the exposed fractured mesial root and accumulated granulation tissue, and the loss of bone height in the furcation. The laser is positioned so that the sapphire tip is directed toward the junction of the crown with the root in a buccal-lingual direction so that the laser energy separates the fractured root from the crown, leaving a smooth tooth surface under the crown. The exposed opening to the canal or chamber under the crown was filled with a glass-ionomer restorative material. This exposed tooth surface will be above the gingiva following the removal of the mesial root of the tooth.
(D) Exposed fractured mesial root.
Fig. E shows the location of the laser sapphire tip before the separation of the root from the crown.
(E) Laser positioned in a buccal-lingual approach before separation of root from crown.
Fig. F is a post-operative view showing the tooth following removal of the root and initiation of healing and bone regeneration.
Fig. G is a six-month post-operative radiograph showing rapid bone regeneration in the extraction area. This patient’s response to therapy was similar to that reported by Haueisen and Heidemann.6 The patient got complete relief after the hemisection. However, the patient also was advised that the tooth might eventually fail, because of a lack of mesial support for the cantilevered portion of the crown once the mesial root was removed.
(G) Six-month post-operative view shows rapid bone regeneration in extraction area.
Case 2: Highspeed handpiece
In the second case, an air turbine handpiece was used to complete the hemisection.
Treatment planning
A 50-year-old male in good general health was seen for a recare examination. He had swelling over the mesial root of the mandibular left first molar. Fig. H is a radiograph of the endodontically treated tooth. The abscess was connected to a fistula draining into the buccal fold. Examination of the tooth showed that the mesial root was fractured vertically, yet the distal root was intact and functioning.
H() View of mesial-root endodontic failure. The mesial root is fractured vertically, but distal root is intact.
Various treatment options discussed included hemisection of the split root, leaving the crown and distal root in place; or extraction and replacement of the tooth with a fixed bridge, removable partial denture, or implant.
Procedure
After all of the risks, benefits, and alternatives were fully discussed, the hemisection procedure was selected, and treatment was performed using the standard air-driven handpiece to separate the split mesial root from the crown. Normal surgical entry was accomplished using a scalpel and tissue elevator. Following removal of the mesial root, healing was normal with closure of the fistula and bone regeneration to the extraction area. Fig. I is a panoramic radiograph taken before the mandibular left first molar had abscessed. Fig. J shows the treated area after hemisection.
(I) Pre-operative panoramic radiograph.
(J) Post-operative panoramic radiograph.
——————–
References
1. Souviron RR, Groh KR. Glossary of dental terminology. Available at: “http://www.dentalleaders.com/ terms.htm”. Accessed Oct. 18, 2006.
2. Reese TM. Procedures—-Root amputation/hemisection. Available at: “http://reesedds.com/hemirootamp. htm”. Accessed Oct. 18, 2006.
3. Parmar G, Vashi P. Hemisection: A case-report and review. Endodontology 2003;15:26-9.
4. Bühler H. Survival rates of hemisected teeth: An attempt to compare them with survival rates of alloplastic implants. Int J Periodont Rest Dent 1994;14:537-43.
5. Noguera AP, Russo PL. Hemisection and root amputation. Available at: “http://dcendo.com/svchemi.htm”. Accessed Oct. 18, 2006.
6. Haueisen H, Heidemann D. Hemisection for treatment of an advanced endodontic-periodonal lesion: A case report. Int Endodontic J 2002;35:557-72.
Related Links: Posted by dentalproducts.net. Originally published in the November 2006 Dental Products Report. Copyright 1999-2005 Advanstar Dental Communications.
Hi my dentist colleagues and dear student friends,
Your first target is trusting yourself and your abilities…
And your first duty is,to know your talents and to
perform them in usefull places…
You have to be number one and it must be the reality for you.
Don’t think to be stay casually.
We are all talent and have responsibilities otherwise we didn’t
choose dentistry which is difficult and full stress job…
Our job is like to climb a mountain…
If we dont have necessary equipments, only we can walk on
the foot of the mountains…
We can find a sample or samples who are succesful and we
have to learn to imagine to be like them…
All things begin with us and they all finish with us too…
Yesim Kale, DMD Istanbul-Turkiye
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